blocked threads - Page 200

Node.js vs PHP processing speed

- by Cody Craven

I've been looking into node.js recently and wanted to see a true comparison of processing speed for PHP vs Node.js. In most of the comparisons I had seen, Node trounced Apache/PHP set ups handily. However all of the tests were small 'hello worlds' that would not accurately reflect any webpage's markup. So I decided to create a basic HTML page with 10,000 hello world paragraph elements. In these tests Node with Cluster was beaten to a pulp by PHP on Nginx utilizing PHP-FPM. So I'm curious if I am misusing Node somehow or if Node is really just this bad at processing power. Note that my results were equivalent outputting "Hello world\n" with text/plain as the HTML, but I only included the HTML as it's closer to the use case I was investigating. My testing box: Core i7-2600 Intel CPU (has 8 threads with 4 cores) 8GB DDR3 RAM Fedora 16 64bit Node.js v0.6.13 Nginx v1.0.13 PHP v5.3.10 (with PHP-FPM) My test scripts: Node.js script var cluster = require('cluster'); var http = require('http'); var numCPUs = require('os').cpus().length; if (cluster.isMaster) { // Fork workers. for (var i = 0; i < numCPUs; i++) { cluster.fork(); } cluster.on('death', function (worker) { console.log('worker ' + worker.pid + ' died'); }); } else { // Worker processes have an HTTP server. http.Server(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write('<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n'); for (var i = 0; i < 10000; i++) { res.write('<p>Hello world</p>\n'); } res.end('</body>\n</html>'); }).listen(80); } This script is adapted from Node.js' documentation at http://nodejs.org/docs/latest/api/cluster.html PHP script <?php echo "<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n"; for ($i = 0; $i < 10000; $i++) { echo "<p>Hello world</p>\n"; } echo "</body>\n</html>"; My results Node.js $ ab -n 500 -c 20 http://speedtest.dev/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Server Hostname: speedtest.dev Server Port: 80 Document Path: / Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 14.603 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95066500 bytes HTML transferred: 95035000 bytes Requests per second: 34.24 [#/sec] (mean) Time per request: 584.123 [ms] (mean) Time per request: 29.206 [ms] (mean, across all concurrent requests) Transfer rate: 6357.45 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 2 Processing: 94 547 405.4 424 2516 Waiting: 0 331 399.3 216 2284 Total: 95 547 405.4 424 2516 Percentage of the requests served within a certain time (ms) 50% 424 66% 607 75% 733 80% 813 90% 1084 95% 1325 98% 1843 99% 2062 100% 2516 (longest request) PHP/Nginx $ ab -n 500 -c 20 http://speedtest.dev/test.php This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: nginx/1.0.13 Server Hostname: speedtest.dev Server Port: 80 Document Path: /test.php Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 0.130 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95109000 bytes HTML transferred: 95035000 bytes Requests per second: 3849.11 [#/sec] (mean) Time per request: 5.196 [ms] (mean) Time per request: 0.260 [ms] (mean, across all concurrent requests) Transfer rate: 715010.65 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 1 Processing: 3 5 0.7 5 7 Waiting: 1 4 0.7 4 7 Total: 3 5 0.7 5 7 Percentage of the requests served within a certain time (ms) 50% 5 66% 5 75% 5 80% 6 90% 6 95% 6 98% 6 99% 6 100% 7 (longest request) Additional details Again what I'm looking for is to find out if I'm doing something wrong with Node.js or if it is really just that slow compared to PHP on Nginx with FPM. I certainly think Node has a real niche that it could fit well, however with these test results (which I really hope I made a mistake with - as I like the idea of Node) lead me to believe that it is a horrible choice for even a modest processing load when compared to PHP (let alone JVM or various other fast solutions). As a final note, I also tried running an Apache Bench test against node with $ ab -n 20 -c 20 http://speedtest.dev/ and consistently received a total test time of greater than 0.900 seconds.

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Cobol: science and fiction

- by user847

There are a few threads about the relevance of the Cobol programming language on this forum, e.g. this thread links to a collection of them. What I am interested in here is a frequently repeated claim based on a study by Gartner from 1997: that there were around 200 billion lines of code in active use at that time! I would like to ask some questions to verify or falsify a couple of related points. My goal is to understand if this statement has any truth to it or if it is totally unrealistic. I apologize in advance for being a little verbose in presenting my line of thought and my own opinion on the things I am not sure about, but I think it might help to put things in context and thus highlight any wrong assumptions and conclusions I have made. Sometimes, the "200 billion lines" number is accompanied by the added claim that this corresponded to 80% of all programming code in any language in active use. Other times, the 80% merely refer to so-called "business code" (or some other vague phrase hinting that the reader is not to count mainstream software, embedded systems or anything else where Cobol is practically non-existent). In the following I assume that the code does not include double-counting of multiple installations of the same software (since that is cheating!). In particular in the time prior to the y2k problem, it has been noted that a lot of Cobol code is already 20 to 30 years old. That would mean it was written in the late 60ies and 70ies. At that time, the market leader was IBM with the IBM/370 mainframe. IBM has put up a historical announcement on his website quoting prices and availability. According to the sheet, prices are about one million dollars for machines with up to half a megabyte of memory. Question 1: How many mainframes have actually been sold? I have not found any numbers for those times; the latest numbers are for the year 2000, again by Gartner. :^( I would guess that the actual number is in the hundreds or the low thousands; if the market size was 50 billion in 2000 and the market has grown exponentially like any other technology, it might have been merely a few billions back in 1970. Since the IBM/370 was sold for twenty years, twenty times a few thousand will result in a couple of ten-thousands of machines (and that is pretty optimistic)! Question 2: How large were the programs in lines of code? I don't know how many bytes of machine code result from one line of source code on that architecture. But since the IBM/370 was a 32-bit machine, any address access must have used 4 bytes plus instruction (2, maybe 3 bytes for that?). If you count in operating system and data for the program, how many lines of code would have fit into the main memory of half a megabyte? Question 3: Was there no standard software? Did every single machine sold run a unique hand-coded system without any standard software? Seriously, even if every machine was programmed from scratch without any reuse of legacy code (wait ... didn't that violate one of the claims we started from to begin with???) we might have O(50,000 l.o.c./machine) * O(20,000 machines) = O(1,000,000,000 l.o.c.). That is still far, far, far away from 200 billion! Am I missing something obvious here? Question 4: How many programmers did we need to write 200 billion lines of code? I am really not sure about this one, but if we take an average of 10 l.o.c. per day, we would need 55 million man-years to achieve this! In the time-frame of 20 to 30 years this would mean that there must have existed two to three million programmers constantly writing, testing, debugging and documenting code. That would be about as many programmers as we have in China today, wouldn't it? Question 5: What about the competition? So far, I have come up with two things here: 1) IBM had their own programming language, PL/I. Above I have assumed that the majority of code has been written exclusively using Cobol. However, all other things being equal I wonder if IBM marketing had really pushed their own development off the market in favor of Cobol on their machines. Was there really no relevant code base of PL/I? 2) Sometimes (also on this board in the thread quoted above) I come across the claim that the "200 billion lines of code" are simply invisible to anybody outside of "governments, banks ..." (and whatnot). Actually, the DoD had funded their own language in order to increase cost effectiveness and reduce the proliferation of programming language. This lead to their use of Ada. Would they really worry about having so many different programming languages if they had predominantly used Cobol? If there was any language running on "government and military" systems outside the perception of mainstream computing, wouldn't that language be Ada? I hope someone can point out any flaws in my assumptions and/or conclusions and shed some light on whether the above claim has any truth to it or not.

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Unknown error in Producer/Consumer program, believe it to be an infinite loop.

- by ray2k

Hello, I am writing a program that is solving the producer/consumer problem, specifically the bounded-buffer version(i believe they mean the same thing). The producer will be generating x number of random numbers, where x is a command line parameter to my program. At the current moment, I believe my program is entering an infinite loop, but I'm not sure why it is occurring. I believe I am executing the semaphores correctly. You compile it like this: gcc -o prodcon prodcon.cpp -lpthread -lrt Then to run, ./prodcon 100(the number of randum nums to produce) This is my code. typedef int buffer_item; #include <stdlib.h> #include <stdio.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #define BUFF_SIZE 10 #define RAND_DIVISOR 100000000 #define TRUE 1 //two threads void *Producer(void *param); void *Consumer(void *param); int insert_item(buffer_item item); int remove_item(buffer_item *item); int returnRandom(); //the global semaphores sem_t empty, full, mutex; //the buffer buffer_item buf[BUFF_SIZE]; //buffer counter int counter; //number of random numbers to produce int numRand; int main(int argc, char** argv) { /* thread ids and attributes */ pthread_t pid, cid; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); numRand = atoi(argv[1]); sem_init(&empty,0,BUFF_SIZE); sem_init(&full,0,0); sem_init(&mutex,0,0); printf("main started\n"); pthread_create(&pid, &attr, Producer, NULL); pthread_create(&cid, &attr, Consumer, NULL); printf("main gets here"); pthread_join(pid, NULL); pthread_join(cid, NULL); printf("main done\n"); return 0; } //generates a randum number between 1 and 100 int returnRandom() { int num; srand(time(NULL)); num = rand() % 100 + 1; return num; } //begin producing items void *Producer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { //sleep for a random period of time int rNum = rand() / RAND_DIVISOR; sleep(rNum); //generate a random number item = returnRandom(); //acquire the empty lock sem_wait(&empty); //acquire the mutex lock sem_wait(&mutex); if(insert_item(item)) { fprintf(stderr, " Producer report error condition\n"); } else { printf("producer produced %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal full */ sem_post(&full); } return NULL; } /* Consumer Thread */ void *Consumer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { /* sleep for a random period of time */ int rNum = rand() / RAND_DIVISOR; sleep(rNum); /* aquire the full lock */ sem_wait(&full); /* aquire the mutex lock */ sem_wait(&mutex); if(remove_item(&item)) { fprintf(stderr, "Consumer report error condition\n"); } else { printf("consumer consumed %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal empty */ sem_post(&empty); } return NULL; } /* Add an item to the buffer */ int insert_item(buffer_item item) { /* When the buffer is not full add the item and increment the counter*/ if(counter < BUFF_SIZE) { buf[counter] = item; counter++; return 0; } else { /* Error the buffer is full */ return -1; } } /* Remove an item from the buffer */ int remove_item(buffer_item *item) { /* When the buffer is not empty remove the item and decrement the counter */ if(counter > 0) { *item = buf[(counter-1)]; counter--; return 0; } else { /* Error buffer empty */ return -1; } }

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null pointer exception at org.hibernate.tuple.AbstractEntityTuplizer.createProxy

- by saurabh

I am using hibernate 3.2 with struts 1.2 framework I got this exception when i m trying to load the object I am using this code to load the object public Currentprofile findById(java.lang.String id) { log.debug("getting Currentprofile instance with id: " + id); try { Currentprofile instance = (Currentprofile) getSession().get( "com.hibermappings.Currentprofile", id); return instance; } catch (RuntimeException re) { log.error("get failed", re); throw re; } } my hbm file is this <one-to-one name="referenceDb" lazy="proxy" class="com.hibermappings.ReferenceDb" cascade="all" constrained="false" /> <one-to-one name="registration" lazy="proxy" class="com.hibermappings.Registration" cascade="all" constrained="false" /> <one-to-one name="jobseekerpackagedetails" lazy="proxy" class="com.hibermappings.Jobseekerpackagedetails" cascade="all" constrained="false" /> <property name="keyWords" type="java.lang.String"> <column name="keyWords" length="5000" /> </property> <property name="totalExp" type="java.lang.String"> <column name="totalExp" length="100" /> </property> <property name="hqualification" type="java.lang.String"> <column name="hQualification" length="100" /> </property> <property name="preferedLocation" type="java.lang.String"> <column name="preferedLocation" length="100" /> </property> <property name="functionalArea" type="java.lang.String"> <column name="functionalArea" length="1000" /> </property> <property name="expSalary" type="java.lang.String"> <column name="expSalary" length="100" /> </property> <property name="designation" type="java.lang.String"> <column name="designation" length="100" /> </property> <property name="resumeTitle" type="java.lang.String"> <column name="resumeTitle" length="500" /> </property> <property name="profileDetails" type="java.lang.String"> <column name="profileDetails" length="65535" /> </property> <property name="requiredProfile" type="java.lang.String"> <column name="requiredProfile" length="65535" /> </property> <property name="activatedOn" type="java.util.Date"> <column name="activatedOn" length="0" /> </property> <set name="resumes" inverse="true" cascade="save-update"> <key> <column name="jobseekerId" length="50" /> </key> <one-to-many class="com.hibermappings.Resume" /> </set> </class> the same code runs well when I m using in a simple java class within main method .. full stack trace of exception is java.lang.NullPointerException at org.hibernate.tuple.AbstractEntityTuplizer.createProxy(AbstractEntityTuplizer.java:372) at org.hibernate.persister.entity.AbstractEntityPersister.createProxy(AbstractEntityPersister.java:3121) at org.hibernate.event.def.DefaultLoadEventListener.createProxyIfNecessary(DefaultLoadEventListener.java:232) at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:173) at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:87) at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:862) at org.hibernate.impl.SessionImpl.load(SessionImpl.java:781) at org.hibernate.impl.SessionImpl.load(SessionImpl.java:774) at com.DAOs.CurrentprofileDAO.getLoad(CurrentprofileDAO.java:71) at com.action.JobSekeerManage.viewProfile(JobSekeerManage.java:447) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270) at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196) at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) at javax.servlet.http.HttpServlet.service(HttpServlet.java:689) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at com.filter.HibernateFilter.doFilter(HibernateFilter.java:24) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:825) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:731) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:526) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684) at java.lang.Thread.run(Thread.java:595) Error::null

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Thread Blocks During Call

- by user578875

I have a serious problem, I'm developing an application that mesures on call time during a call; the problem presents when, with the phone on the ear, the thread that the timer has, blocks and no longer responds before taking off my ear. The next log shows the problem. 01-11 16:14:19.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:20.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:21.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:22.597 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:23.608 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:24.017 1106 1106 D iddd : select() < 0, Probably a handled signal: Interrupted system call 01-11 16:14:24.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:05.500 1106 1106 D iddd : select() < 0, Probably a handled signal: Interrupted system call 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service I've been trying with Services, Timers, Threads, AyncTasks and they all present the same problem. My Code: @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); setContentView(R.layout.main); HangUpService.setMainActivity(this); objHangUpService = new Intent(this, HangUpService.class); Runnable rAccion = new Runnable() { public void run() { TelephonyManager tm = (TelephonyManager)getSystemService(TELEPHONY_SERVICE); tm.listen(mPhoneListener, PhoneStateListener.LISTEN_CALL_STATE); objVibrator = (Vibrator) getSystemService(getApplicationContext().VIBRATOR_SERVICE); final ListView lstLlamadas = (ListView) findViewById(R.id.lstFavoritos); final EditText txtMinutos = (EditText) findViewById(R.id.txtMinutos); final EditText txtSegundos = (EditText) findViewById(R.id.txtSegundos); ArrayList<Contacto> cContactos = new ArrayList<Contacto>(); ContactoAdapter caContactos = new ContactoAdapter(HangUp.this, R.layout.row,cContactos); Cursor curContactos = getContentResolver().query( ContactsContract.Contacts.CONTENT_URI, null, null, null, ContactsContract.Contacts.TIMES_CONTACTED + " DESC"); while (curContactos.moveToNext()){ String strNombre = curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)); String strID = curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts._ID)); String strHasPhone=curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)); String strStarred=curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.STARRED)); if (Integer.parseInt(strHasPhone) > 0 && Integer.parseInt(strStarred) ==1 ) { Cursor CursorTelefono = getContentResolver().query( ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = " + strID, null, null); while (CursorTelefono.moveToNext()) { String strTipo=CursorTelefono.getString(CursorTelefono.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE)); String strTelefono=CursorTelefono.getString(CursorTelefono.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)); strNumero=strTelefono; String args[]=new String[1]; args[0]=strNumero; Cursor CursorCallLog = getContentResolver().query( android.provider.CallLog.Calls.CONTENT_URI, null, android.provider.CallLog.Calls.NUMBER + "=?", args, android.provider.CallLog.Calls.DATE+ " DESC"); if (Integer.parseInt(strTipo)==2) { caContactos.add( new Contacto( strNombre, strTelefono ) ); } } CursorTelefono.close(); } } curContactos.close(); lstLlamadas.setAdapter(caContactos); lstLlamadas.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView a, View v, int position, long id) { Contacto mContacto=(Contacto)lstLlamadas.getItemAtPosition(position); i = new Intent(HangUp.this, Llamada.class); Log.i("Estado","Declaro Intent"); Bundle bundle = new Bundle(); bundle.putString("telefono", mContacto.getTelefono()); i.putExtras(bundle); startActivityForResult(i,SUB_ACTIVITY_ID); Log.i("Estado","Inicio Intent"); blActivo=true; try { String strMinutos=txtMinutos.getText().toString(); String strSegundos=txtSegundos.getText().toString(); if(!strMinutos.equals("") && !strSegundos.equals("")){ int Tiempo = ( (Integer.parseInt(txtMinutos.getText().toString())*60) + Integer.parseInt(txtSegundos.getText().toString()) )* 1000; handler.removeCallbacks(rVibrate); cTime = System.currentTimeMillis(); cTime=cTime+Tiempo; objHangUpAsync = new HangUpAsync(cTime,objVibrator,objPowerManager,objKeyguardLock); objHangUpAsync.execute(); objPowerManager.userActivity(Tiempo+3000, true); objHangUpService.putExtra("cTime", cTime); //startService(objHangUpService); } catch (Exception e) { e.printStackTrace(); } finally { } } }); } }; } AsyncTask: @Override protected String doInBackground(String... arg0) { blActivo = true; mWakeLock = objPowerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Tag"); objKeyguardLock.disableKeyguard(); Log.i("Estado", "Entro a doInBackground"); timer.scheduleAtFixedRate( new TimerTask() { public void run() { if (blActivo){ if (cTime blActivo=false; objVibrator.vibrate(1000); Log.i("Estado","Vibrar desde Async"); this.cancel(); }else{ try{ mWakeLock.acquire(); mWakeLock.release(); Log.i("Estado","postDelayed Async Service"); }catch(Exception e){ Log.i("Estado","Error: " + e.getMessage()); } } } } }, 0, INTERVAL); return null; }

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(C++) Linking with namespaces causes duplicate symbol error

- by user577072

Hello. For the past few days, I have been trying to figure out how to link the files for a CLI gaming project I have been working on. There are two halves of the project, the Client and the Server code. The client needs two libraries I've made. The first is a general purpose game board. This is split between GameEngine.h and GameEngine.cpp. The header file looks something like this namespace gfdGaming { // struct sqr_size { // Index x; // Index y; // }; typedef struct { Index x, y; } sqr_size; const sqr_size sPos = {1, 1}; sqr_size sqr(Index x, Index y); sqr_size ePos; class board { // Prototypes / declarations for the class } } And the CPP file is just giving everything content #include "GameEngine.h" type gfdGaming::board::functions The client also has game-specific code (in this case, TicTacToe) split into declarations and definitions (TTT.h, Client.cpp). TTT.h is basically #include "GameEngine.h" #define TTTtar "localhost" #define TTTport 2886 using namespace gfdGaming; void* turnHandler(void*); namespace nsTicTacToe { GFDCON gfd; const char X = 'X'; const char O = 'O'; string MPhostname, mySID; board TTTboard; bool PlayerIsX = true, isMyTurn; char Player = X, Player2 = O; int recon(string* datHolder = NULL, bool force = false); void initMP(bool create = false, string hn = TTTtar); void init(); bool isTie(); int turnPlayer(Index loc, char lSym = Player); bool checkWin(char sym = Player); int mainloop(); int mainloopMP(); }; // NS I made the decision to put this in a namespace to group it instead of a class because there are some parts that would not work well in OOP, and it's much easier to implement later on. I have had trouble linking the client in the past, but this setup seems to work. My server is also split into two files, Server.h and Server.cpp. Server.h contains exactly: #include "../TicTacToe/TTT.h" // Server needs a full copy of TicTacToe code class TTTserv; struct TTTachievement_requirement { Index id; Index loc; bool inUse; }; struct TTTachievement_t { Index id; bool achieved; bool AND, inSameGame; bool inUse; bool (*lHandler)(TTTserv*); char mustBeSym; int mustBePlayer; string name, description; TTTachievement_requirement steps[safearray(8*8)]; }; class achievement_core_t : public GfdOogleTech { public: // May be shifted to private TTTachievement_t list[safearray(8*8)]; public: achievement_core_t(); int insert(string name, string d, bool samegame, bool lAnd, int lSteps[8*8], int mbP=0, char mbS=0); }; struct TTTplayer_t { Index id; bool inUse; string ip, sessionID; char sym; int desc; TTTachievement_t Ding[8*8]; }; struct TTTgame_t { TTTplayer_t Player[safearray(2)]; TTTplayer_t Spectator; achievement_core_t achievement_core; Index cTurn, players; port_t roomLoc; bool inGame, Xused, Oused, newEvent; }; class TTTserv : public gSserver { TTTgame_t Game; TTTplayer_t *cPlayer; port_t conPort; public: achievement_core_t *achiev; thread threads[8]; int parseit(string tDat, string tsIP); Index conCount; int parseit(string tDat, int tlUser, TTTplayer_t** retval); private: int parseProto(string dat, string sIP); int parseProto(string dat, int lUser); int cycleTurn(); void setup(port_t lPort = 0, bool complete = false); public: int newEvent; TTTserv(port_t tlPort = TTTport, bool tcomplete = true); TTTplayer_t* userDC(Index id, Index force = false); int sendToPlayers(string dat, bool asMSG = false); int mainLoop(volatile bool *play); }; // Other void* userHandler(void*); void* handleUser(void*); And in the CPP file I include Server.h and provide main() and the contents of all functions previously declared. Now to the problem at hand I am having issues when linking my server. More specifically, I get a duplicate symbol error for every variable in nsTicTacToe (and possibly in gfdGaming as well). Since I need the TicTacToe functions, I link Client.cpp ( without main() ) when building the server ld: duplicate symbol nsTicTacToe::PlayerIsX in Client.o and Server.o collect2: ld returned 1 exit status Command /Developer/usr/bin/g++-4.2 failed with exit code 1 It stops once a problem is encountered, but if PlayerIsX is removed / changed temporarily than another variable causes an error Essentially, I am looking for any advice on how to better organize my code to hopefully fix these errors. Disclaimers: -I apologize in advance if I provided too much or too little information, as it is my first time posting -I have tried using static and extern to fix these problems, but apparently those are not what I need Thank you to anyone who takes the time to read all of this and respond =)

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Compile error with initializer_list when trying to use it to initialize member value of class

- by ilektron

I am trying to make a class initializable from an initialization_list in a class constructor's constructor's initialization list. It works for a std::map, but not for my custom class. I don't see any difference other than templates are used in std::map. #include <iostream> #include <initializer_list> #include <string> #include <sstream> #include <map> using std::string; class text_thing { private: string m_text; public: text_thing() { } text_thing(text_thing& other); text_thing(std::initializer_list< std::pair<const string, const string> >& il); text_thing& operator=(std::initializer_list< std::pair<const string, const string> >& il); operator string() { return m_text; } }; class static_base { private: std::map<string, string> m_test_map; text_thing m_thing; static_base(); public: static static_base& getInstance() { static static_base instance; return instance; } string getText() { return (string)m_thing; } }; typedef std::pair<const string, const string> spair; text_thing::text_thing(text_thing& other) { m_text = other.m_text; } text_thing::text_thing(std::initializer_list< std::pair<const string, const string> >& il) { std::stringstream text_gen; for (auto& apair : il) { text_gen << "{" << apair.first << ", " << apair.second << "}" << std::endl; } } text_thing& text_thing::operator=(std::initializer_list< std::pair<const string, const string> >& il) { std::stringstream text_gen; for (auto& apair : il) { text_gen << "{" << apair.first << ", " << apair.second << "}" << std::endl; } return *this; } static_base::static_base() : m_test_map{{"test", "1"}, {"test2", "2"}}, // Compiler fine with this m_thing{{"test", "1"}, {"test2", "2"}} // Compiler doesn't like this { } int main() { std::cout << "Starting the program" << std::endl; std::cout << "The text thing: " << std::endl << static_base::getInstance().getText(); } I get this compiler output g++ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++11 -MMD -MP -MF"static_base.d" -MT"static_base.d" -o "static_base.o" "../static_base.cpp" Finished building: ../static_base.cpp Building file: ../test.cpp Invoking: GCC C++ Compiler g++ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++11 -MMD -MP -MF"test.d" -MT"test.d" -o "test.o" "../test.cpp" ../test.cpp: In constructor ‘static_base::static_base()’: ../test.cpp:94:40: error: no matching function for call to ‘text_thing::text_thing(<brace-enclosed initializer list>)’ m_thing{{"test", "1"}, {"test2", "2"}} ^ ../test.cpp:94:40: note: candidates are: ../test.cpp:72:1: note: text_thing::text_thing(std::initializer_list<std::pair<const std::basic_string<char>, const std::basic_string<char> > >&) text_thing::text_thing(std::initializer_list< std::pair<const string, const string> >& il) ^ ../test.cpp:72:1: note: candidate expects 1 argument, 2 provided ../test.cpp:67:1: note: text_thing::text_thing(text_thing&) text_thing::text_thing(text_thing& other) ^ ../test.cpp:67:1: note: candidate expects 1 argument, 2 provided ../test.cpp:23:2: note: text_thing::text_thing() text_thing() ^ ../test.cpp:23:2: note: candidate expects 0 arguments, 2 provided make: *** [test.o] Error 1 Output of gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.1-2ubuntu1~13.04' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.8.1 (Ubuntu 4.8.1-2ubuntu1~13.04) It compiles fine with the std::map constructed this way, and if I modify the static_base to return the strings from the maps, all is fine and dandy. Please help me understand what is going on here.

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modalpopupextender.Show() wont fire

- by Peter Lea

I'm pretty new to developing for the web so bare with me. I have a company page with multiple locations and emails etc at each of these addresses. The idea is to have a single modalpopup to edit each type of data (one for email, one for urls, one for addresses etc). I link the modalpopupextender to a hiddenbutton and then call an edit function from various places where I can populate some hiddenfields and textboxes in the panel before showing it. The code executes but it just wont show the damn popup, I just see a flash and can't figure out if its my panel, my css or something I don't understand about ajax and postbacks etc. Things i've tried after reading various threads: Disable smart navigation in web.config Move ToolKitScriptManager up to master page and use proxy in content set hiddenbutton to use style="display:none" tried links etc instead of hidden button Heres my code CSS .modalBackground { position: absolute; z-index: 100; top: 0px; left: 0px; background-color: #000; filter: alpha(opacity=60); -moz-opacity: 0.6; opacity: 0.6; } .modalPopup { background-color: #FFD; border-width: 3px; border-style: solid; border-color: gray; padding: 3px;} Asp/html <ajaxToolkit:ModalPopupExtender runat="server" ID="mpe_email" BackgroundCssClass="modalBackground" PopupControlID="modal_email" CancelControlID="btn_cancel_email" TargetControlID="fake_btn_email" /> <asp:Button ID="fake_btn_email" runat="server" Text="email" style="display:none;" /> <asp:panel id="modal_email" runat="server" class="modalPopup" Width="500px" Height="500px"> <asp:HiddenField ID="hf_modal_email_location_id" runat="server" Value="" /> <asp:HiddenField ID="hf_modal_email_contact_id" runat="server" Value="" /> <asp:HiddenField ID="hf_modal_email_comms_id" runat="server" Value="" /> <table width="100%"> <tr> <td> <asp:Label ID="lbl_mpe_email_title" runat="server" Text="Edit Email Address" /> </td> </tr> <tr> <td> <table width="100%"> <tr> <td width="40px"><img src="../images/email.png" height="30px" width="30px"/></td> <td> <table width="100px"> <tr> <td><span>Quick Ref: <asp:TextBox ID="txb_mpe_email_qref" runat="server" Text="" /></span></td> </tr> <tr> <td><span>Email Address: <asp:TextBox ID="txb_mpe_email_address_full" runat="server" Text="" /></span></td> </tr> </table> </td> </tr> </table> </td> </tr> <tr> <td width="40px" align="left"><asp:Button ID="btn_cancel_email" runat="server" Text="Cancel"/></td> <td align="right"><asp:Button ID="btn_save_email" runat="server" Text="Save" OnCommand="save_modal_email" /></td> </tr> <tr> <td colspan="2" align="right"><asp:Label ID="lbl_mpe_email_err" runat="server" Text="" /></td> </tr> </table> c# public void oloc_ocon_email_edit(object sender, RepeaterCommandEventArgs e) { switch (e.CommandName) { case "edit": hf_modal_email_location_id.Value = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_location_id")).Value; hf_modal_email_contact_id.Value = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_contact_id")).Value; hf_modal_email_comms_id.Value = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_comms_id")).Value; lbl_mpe_email_title.Text = "Edit Email Address"; txb_mpe_email_qref.Text = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_qref")).Value; txb_mpe_email_address_full.Text = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_email_full")).Value; lbl_mpe_email_err.Text = ""; mpe_email.Show(); break; case "new": hf_modal_email_location_id.Value = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_location_id_p")).Value; hf_modal_email_contact_id.Value = ((HiddenField)e.Item.FindControl("hf_oloc_ocon_emails_contact_id_p")).Value; hf_modal_email_comms_id.Value = "0"; lbl_mpe_email_title.Text = "New Email Address"; txb_mpe_email_qref.Text = ""; txb_mpe_email_address_full.Text = ""; lbl_mpe_email_err.Text = ""; mpe_email.Show(); break; } } Stuff makes so much more sense in a desktop environment, I hope someone can point me in the right direction. Thanks

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jQuery Validation plugin: prompt for override

- by Sam Carleton

I have a jQuery form that has validation of a sort. It is a data entry screen with two 'recommend ranges', one is 36-84, the other 50-300. The business rules call for the values to be either blank or greater than zero, but to prompt for confirmation if the values are outside of the range listed above. I have seen some other threads that talk about setting the class="cancel" on the submit button. From what I can tell, this will simply disable the validation. I need to prompt for a "do you want to continue, yes or no?" and if no stop the submit, if yes, continue. Below is an example from the book Pro jQuery. By default the top row needs to be between 10 and 20 to submit. How would you change it so that it prompts you and if you say Yes it submits, no prevents the submit: <!DOCTYPE html> <html> <head> <title>Example</title> <script src="jquery-1.7.js" type="text/javascript"></script> <script src="jquery.tmpl.js" type="text/javascript"></script> <script src="jquery.validate.js" type="text/javascript"></script> <style type="text/css"> h1 { min-width: 70px; border: thick double black; margin-left: auto; margin-right: auto; text-align: center; font-size: x-large; padding: .5em; color: darkgreen; background-image: url("border.png"); background-size: contain; margin-top: 0; } .dtable {display: table;} .drow {display: table-row;} .dcell {display: table-cell; padding: 10px;} .dcell > * {vertical-align: middle} input {width: 2em; text-align: right; border: thin solid black; padding: 2px;} label {width: 5em; padding-left: .5em; display: inline-block;} #buttonDiv {text-align: center;} #oblock {display: block; margin-left: auto; margin-right: auto; min-width: 700px; } div.errorMsg {color: red} .invalidElem {border: medium solid red} </style> <script type="text/javascript"> $(document).ready(function() { var data = [ { name: "Astor", product: "astor", stocklevel: "10", price: "2.99"}, { name: "Daffodil", product: "daffodil", stocklevel: "12", price: "1.99"}, { name: "Rose", product: "rose", stocklevel: "2", price: "4.99"}, { name: "Peony", product: "peony", stocklevel: "0", price: "1.50"}, { name: "Primula", product: "primula", stocklevel: "1", price: "3.12"}, { name: "Snowdrop", product: "snowdrop", stocklevel: "15", price: "0.99"}, ]; var templResult = $('#flowerTmpl').tmpl(data); templResult.slice(0, 3).appendTo('#row1'); templResult.slice(3).appendTo("#row2"); $('form').validate({ highlight: function(element, errorClass) { $(element).add($(element).parent()).addClass("invalidElem"); }, unhighlight: function(element, errorClass) { $(element).add($(element).parent()).removeClass("invalidElem"); }, errorElement: "div", errorClass: "errorMsg" }); $.validator.addClassRules({ flowerValidation: { required: true, min: 0, max: 100, digits: true, } }) $('#row1 input').each(function(index, elem) { $(elem).rules("add", { min: 10, max: 20 }) }); $('input').addClass("flowerValidation").change(function(e) { $('form').validate().element($(e.target)); }); }); </script> <script id="flowerTmpl" type="text/x-jquery-tmpl"> <div class="dcell"> <img src="${product}.png"/> <label for="${product}">${name}: </label> <input name="${product}" value="0" required /> </div> </script> </head> <body> <h1>Jacqui's Flower Shop</h1> <form method="post" action="http://node.jacquisflowershop.com/order"> <div id="oblock"> <div class="dtable"> <div id="row1" class="drow"> </div> <div id="row2"class="drow"> </div> </div> </div> <div id="buttonDiv"><button type="submit">Place Order</button></div> </form> </body> </html>

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Application crashing when talking to oracle unless executable path contains spaces

- by Lasse V. Karlsen

We have an x-files problem with our .NET application. Or, rather, hybrid Win32 and .NET application. When it attempts to communicate with Oracle, it just dies. Vanishes. Goes to the big black void in the sky. No event log message, no exception, no nothing. If we simply ask the application to talk to a MS SQL Server instead, which has the effect of replacing the usage of OracleConnection and related classes with SqlConnection and related classes, it works as expected. Today we had a breakthrough. For some reason, a customer had figured out that by placing all the application files in a directory on his desktop, it worked as expected with Oracle as well. Moving the directory down to the root of the drive, or in C:\Temp or, well, around a bit, made the crash reappear. Basically it was 100% reproducable that the application worked if run from directory on desktop, and failed if run from directory in root. Today we figured out that the difference that counted was wether there was a space in the directory name or not. So, these directories would work: C:\Program Files\AppDir\Executable.exe C:\Temp Lemp\AppDir\Executable.exe C:\Documents and Settings\someuser\Desktop\AppDir\Executable.exe whereas these would not: C:\CompanyName\AppDir\Executable.exe C:\Programfiler\AppDir\Executable.exe <-- Program Files in norwegian C:\Temp\AppDir\Executable.exe I'm hoping someone reading this has seen similar behavior and have a "aha, you need to twiddle the frob on the oracle glitz driver configuration" or similar. Anyone? Followup #1: Ok, I've processed the procmon output now, both files from when I hit the button that attempts to open the window that triggers the cascade failure, and I've noticed that they keep track mostly, there's some smallish differences near the top of both files, and they they keep track a long way down. However, when one run fails, the other keeps going and the next few lines of the log output are these: ReadFile C:\oracle\product\10.2.0\db_1\BIN\orageneric10.dll SUCCESS Offset: 274 432, Length: 32 768, I/O Flags: Non-cached, Paging I/O, Synchronous Paging I/O ReadFile C:\oracle\product\10.2.0\db_1\BIN\orageneric10.dll SUCCESS Offset: 233 472, Length: 32 768, I/O Flags: Non-cached, Paging I/O, Synchronous Paging I/O After this, the working run continues to execute, and the other touches the mscorwks.dll files a few times before threads close down and the app closes. Thus, the failed run does not touch the above files. Followup #2: Figured I'd try to upgrade the oracle client drivers, but 10.2.0.1 is apparently the highest version available for Windows 2003 server and XP clients. Followup #3: Well, we've ended up with a black-box solution. Basically we found that the problem is somewhere related to XPO and Oracle. XPO has a system-table it manages, called XPObjectType, with three columns: Oid, TypeName and AssemblyName. Due to how Oracle is configured in the databases we talk to, the column names were OID, TYPENAME and ASSEMBLYNAME. This would ordinarily not be a problem, except that XPO talks to the schema information directly and checks if the table is there with the right column names, and XPO doesn't handle case differences so it sees a XPObjectType table with three unknown columns and none of those it expects. Exactly what XPO does now I don't really know, but if I dropped this table, and recreated it with the right case, using double quotes around all the column names to get the case right, the problem doesn't crop up. Exactly where the space in the folder name comes into this, I still have no idea, but this problem had two tiers: Stop the application from crashing at our customers, short-term solution Fix the bug, long-term solution Right now tier 1 is solved, tier 2 will be put back into the queue for now and prioritized. We're facing some bigger changes to our data tier anyway so this might not be a problem we need to solve, at least if all our Oracle-customers verify that the table-fix actually gets rid of the problem. I'll accept the answer by Dave Markle since though Process Monitor (the big brother of File Monitor) didn't actually pinpoint the problem, I was able to use it to determine that after my breakpoint in user-code where XPO had built up the query for this table, no I/O happened until all the entries for the application closing down was logged, which led me to believe it was this table that was the culprit, or at least influenced the problem somehow. If I manage to get to the real cause of this, I'll update the post.

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Is multithreading the right way to go for my case?

- by Julien Lebosquain

Hello, I'm currently designing a multi-client / server application. I'm using plain good old sockets because WCF or similar technology is not what I need. Let me explain: it isn't the classical case of a client simply calling a service; all clients can 'interact' with each other by sending a packet to the server, which will then do some action, and possible re-dispatch an answer message to one or more clients. Although doable with WCF, the application will get pretty complex with hundreds of different messages. For each connected client, I'm of course using asynchronous methods to send and receive bytes. I've got the messages fully working, everything's fine. Except that for each line of code I'm writing, my head just burns because of multithreading issues. Since there could be around 200 clients connected at the same time, I chose to go the fully multithreaded way: each received message on a socket is immediately processed on the thread pool thread it was received, not on a single consumer thread. Since each client can interact with other clients, and indirectly with shared objects on the server, I must protect almost every object that is mutable. I first went with a ReaderWriterLockSlim for each resource that must be protected, but quickly noticed that there are more writes overall than reads in the server application, and switched to the well-known Monitor to simplify the code. So far, so good. Each resource is protected, I have helper classes that I must use to get a lock and its protected resource, so I can't use an object without getting a lock. Moreover, each client has its own lock that is entered as soon as a packet is received from its socket. It's done to prevent other clients from making changes to the state of this client while it has some messages being processed, which is something that will happen frequently. Now, I don't just need to protect resources from concurrent accesses. I must keep every client in sync with the server for some collections I have. One tricky part that I'm currently struggling with is the following: I have a collection of clients. Each client has its own unique ID. When a client connects, it must receive the IDs of every connected client, and each one of them must be notified of the newcomer's ID. When a client disconnects, every other client must know it so that its ID is no longer valid for them. Every client must always have, at a given time, the same clients collection as the server so that I can assume that everybody knows everybody. This way if I'm sending a message to client #1 telling "Client #2 has done something", I know that it will always be correctly interpreted: Client 1 will never wonder "but who is Client 2 anyway?". My first attempt for handling the connection of a new client (let's call it X) was this pseudo-code (remember that newClient is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("newClient with id X has connected"); } } clients.Add(newClient); newClient.Send("the list of other clients"); } Now imagine that in the same time, another client has sent a packet that translates into a message that must be broadcasted to every connected client, the pseudo-code will be something like this (remember that the current client - let's call it Y - is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("something"); } } } An obvious deadlock occurs here: on one thread X is locked, the clients lock has been entered, started looping through the clients, and at one moment must get Y's lock... which is already acquired on the second thread, itself waiting for the clients collection lock to be released! This is not the only case like this in the server application. There are other collections which must be kept in sync with the clients, some properties on a client can be changed by another one, etc. I tried other types of locks, lock-free mechanisms and a bunch of other things. Either there were obvious deadlocks when I'm using too much locks for safety, or obvious race conditions otherwise. When I finally find a good middle point between the two, it usually comes with very subtle race conditions / dead locks and other multi-threading issues... my head hurts very quickly since for any single line of code I'm writing I have to review almost the whole application to ensure everything will behave correctly with any number of threads. So here's my final question: how would you resolve this specific case, the general case, and more importantly: aren't I going the wrong way here? I have little problems with the .NET framework, C#, simple concurrency or algorithms in general. Still, I'm lost here. I know I could use only one thread processing the incoming requests and everything will be fine. However, that won't scale well at all with more clients... But I'm thinking more and more to go this simple way. What do you think? Thanks in advance to you, StackOverflow people which have taken the time to read this huge question. I really had to explain the whole context if I want to get some help.

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Transferring data from 2d Dynamic array in C to CUDA and back

- by Soumya

I have a dynamically declared 2D array in my C program, the contents of which I want to transfer to a CUDA kernel for further processing. Once processed, I want to populate the dynamically declared 2D array in my C code with the CUDA processed data. I am able to do this with static 2D C arrays but not with dynamically declared C arrays. Any inputs would be welcome! I mean the dynamic array of dynamic arrays. The test code that I have written is as below. #include "cuda_runtime.h" #include "device_launch_parameters.h" #include <stdio.h> #include <conio.h> #include <math.h> #include <stdlib.h> const int nItt = 10; const int nP = 5; __device__ int d_nItt = 10; __device__ int d_nP = 5; __global__ void arr_chk(float *d_x_k, float *d_w_k, int row_num) { int index = (blockIdx.x * blockDim.x) + threadIdx.x; int index1 = (row_num * d_nP) + index; if ( (index1 >= row_num * d_nP) && (index1 < ((row_num +1)*d_nP))) //Modifying only one row data pertaining to one particular iteration { d_x_k[index1] = row_num * d_nP; d_w_k[index1] = index; } } float **mat_create2(int r, int c) { float **dynamicArray; dynamicArray = (float **) malloc (sizeof (float)*r); for(int i=0; i<r; i++) { dynamicArray[i] = (float *) malloc (sizeof (float)*c); for(int j= 0; j<c;j++) { dynamicArray[i][j] = 0; } } return dynamicArray; } /* Freeing memory - here only number of rows are passed*/ void cleanup2d(float **mat_arr, int x) { int i; for(i=0; i<x; i++) { free(mat_arr[i]); } free(mat_arr); } int main() { //float w_k[nItt][nP]; //Static array declaration - works! //float x_k[nItt][nP]; // if I uncomment this dynamic declaration and comment the static one, it does not work..... float **w_k = mat_create2(nItt,nP); float **x_k = mat_create2(nItt,nP); float *d_w_k, *d_x_k; // Device variables for w_k and x_k int nblocks, blocksize, nthreads; for(int i=0;i<nItt;i++) { for(int j=0;j<nP;j++) { x_k[i][j] = (nP*i); w_k[i][j] = j; } } for(int i=0;i<nItt;i++) { for(int j=0;j<nP;j++) { printf("x_k[%d][%d] = %f\t",i,j,x_k[i][j]); printf("w_k[%d][%d] = %f\n",i,j,w_k[i][j]); } } int size1 = nItt * nP * sizeof(float); printf("\nThe array size in memory bytes is: %d\n",size1); cudaMalloc( (void**)&d_x_k, size1 ); cudaMalloc( (void**)&d_w_k, size1 ); if((nP*nItt)<32) { blocksize = nP*nItt; nblocks = 1; } else { blocksize = 32; // Defines the number of threads running per block. Taken equal to warp size nthreads = blocksize; nblocks = ceil(float(nP*nItt) / nthreads); // Calculated total number of blocks thus required } for(int i = 0; i< nItt; i++) { cudaMemcpy( d_x_k, x_k, size1,cudaMemcpyHostToDevice ); //copy of x_k to device cudaMemcpy( d_w_k, w_k, size1,cudaMemcpyHostToDevice ); //copy of w_k to device arr_chk<<<nblocks, blocksize>>>(d_x_k,d_w_k,i); cudaMemcpy( x_k, d_x_k, size1, cudaMemcpyDeviceToHost ); cudaMemcpy( w_k, d_w_k, size1, cudaMemcpyDeviceToHost ); } printf("\nVerification after return from gpu\n"); for(int i = 0; i<nItt; i++) { for(int j=0;j<nP;j++) { printf("x_k[%d][%d] = %f\t",i,j,x_k[i][j]); printf("w_k[%d][%d] = %f\n",i,j,w_k[i][j]); } } cudaFree( d_x_k ); cudaFree( d_w_k ); cleanup2d(x_k,nItt); cleanup2d(w_k,nItt); getch(); return 0;

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Django + dbxml + Apache = problems. Any solutions?

- by Jason

I'm trying to set up a Django application using WSGI. That works fine. However, I am having some issues with part of my Django app that uses BDB XML. My Apache config is as follows: Listen 8000 WSGISocketPrefix /tmp/wsgi <VirtualHost *:8000> ServerName <server name> DocumentRoot <path to doc root> LogLevel info WSGIScriptAlias / <path to wsgi> WSGIApplicationGroup %{GLOBAL} WSGIDaemonProcess debug threads=1 WSGIProcessGroup debug </VirtualHost> However, I'm still getting the following error: DB_ENV->repmgr_stat interface requires an environment configured for the replication subsystem [error] child died with signal 11 My environment is opened as: environment = DBEnv() environment.open( <absolute db env path>, DB_CREATE|DB_INIT_LOCK|DB_INIT_LOG|DB_INIT_MPOOL, 0 ) I am using: python 2.6.2 apache 2.2 ubuntu 9.04 dbxml 2.5.13 compiled from source (so libdb-4.8, bsddb3, all that jazz) I see Apache seems to link to libdb-4.6. Is this a problem? ldd /usr/sbin/apache2 | grep libdb libdb-4.6.so => /usr/lib/libdb-4.6.so (0xb7c01000) Updated Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0xb5a48b90 (LWP 12700)] 0x00000000 in ?? () (gdb) thread apply all bt Thread 4 (Thread 0xb6a67b90 (LWP 12698)): #0 0xb7f11422 in __kernel_vsyscall () #1 0xb7de07b1 in select () from /lib/tls/i686/cmov/libc.so.6 #2 0xb7ea5bcf in apr_sleep () from /usr/lib/libapr-1.so.0 #3 0xb6d7afee in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #4 0xb7ea38ec in ?? () from /usr/lib/libapr-1.so.0 #5 0xb7e6d4ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0 #6 0xb7de849e in clone () from /lib/tls/i686/cmov/libc.so.6 Thread 3 (Thread 0xb6249b90 (LWP 12699)): #0 0xb7f11422 in __kernel_vsyscall () #1 0xb7de07b1 in select () from /lib/tls/i686/cmov/libc.so.6 #2 0xb7ea5bcf in apr_sleep () from /usr/lib/libapr-1.so.0 #3 0xb6d7ab39 in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #4 0xb7ea38ec in ?? () from /usr/lib/libapr-1.so.0 #5 0xb7e6d4ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0 #6 0xb7de849e in clone () from /lib/tls/i686/cmov/libc.so.6 Thread 2 (Thread 0xb5a48b90 (LWP 12700)): #0 0x00000000 in ?? () #1 0xb4f03b5e in DbXml::XmlManager::XmlManager () from /home/jason/dbxml-2.5.13/install/lib/libdbxml-2.5.so #2 0xb501b29b in _wrap_new_XmlManager (self=0x0, args=0xac66fcc) at dbxml_python_wrap.cpp:5183 #3 0xb6b77aed in PyCFunction_Call () from /usr/lib/libpython2.6.so.1.0 #4 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #5 0xb6bd70b5 in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #6 0xb6bdb910 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0 #7 0xb6b6187a in ?? () from /usr/lib/libpython2.6.so.1.0 #8 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #9 0xb6b427a8 in ?? () from /usr/lib/libpython2.6.so.1.0 #10 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #11 0xb6b9ae03 in ?? () from /usr/lib/libpython2.6.so.1.0 #12 0xb6b90f55 in ?? () from /usr/lib/libpython2.6.so.1.0 #13 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #14 0xb6bd7618 in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #15 0xb6bdb910 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0 #16 0xb6b6187a in ?? () from /usr/lib/libpython2.6.so.1.0 #17 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #18 0xb6b427a8 in ?? () from /usr/lib/libpython2.6.so.1.0 #19 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #20 0xb6bd3a34 in PyEval_CallObjectWithKeywords () from /usr/lib/libpython2.6.so.1.0 #21 0xb6b44a7d in PyInstance_New () from /usr/lib/libpython2.6.so.1.0 #22 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #23 0xb6bd7618 in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #24 0xb6bdb910 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0 #25 0xb6b61969 in ?? () from /usr/lib/libpython2.6.so.1.0 #26 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #27 0xb6bd70b5 in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #28 0xb6bdb910 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0 #29 0xb6b61969 in ?? () from /usr/lib/libpython2.6.so.1.0 #30 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #31 0xb6b427a8 in ?? () from /usr/lib/libpython2.6.so.1.0 #32 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #33 0xb6b9b483 in ?? () from /usr/lib/libpython2.6.so.1.0 #34 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #35 0xb6bd70b5 in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #36 0xb6bdab4f in PyEval_EvalFrameEx () from /usr/lib/libpython2.6.so.1.0 #37 0xb6bdb910 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0 #38 0xb6b6187a in ?? () from /usr/lib/libpython2.6.so.1.0 #39 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #40 0xb6b427a8 in ?? () from /usr/lib/libpython2.6.so.1.0 #41 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #42 0xb6b9b483 in ?? () from /usr/lib/libpython2.6.so.1.0 #43 0xb6b3198c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0 #44 0xb6bd3a34 in PyEval_CallObjectWithKeywords () from /usr/lib/libpython2.6.so.1.0 #45 0xb6d7172d in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #46 0xb6d7539f in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #47 0xb6d7e1d8 in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #48 0xb6d7a42c in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #49 0xb6d7a8bd in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #50 0xb6d7a9c5 in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #51 0xb7ea38ec in ?? () from /usr/lib/libapr-1.so.0 #52 0xb7e6d4ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0 #53 0xb7de849e in clone () from /lib/tls/i686/cmov/libc.so.6 Thread 1 (Thread 0xb7460b00 (LWP 12697)): #0 0xb7f11422 in __kernel_vsyscall () #1 0xb7e75300 in sigwait () from /lib/tls/i686/cmov/libpthread.so.0 #2 0xb7ea3f3b in apr_signal_thread () from /usr/lib/libapr-1.so.0 #3 0xb6d7b48d in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #4 0xb6d7bc98 in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #5 0xb6d79632 in ?? () from /usr/lib/apache2/modules/mod_wsgi.so #6 0xb7e9a2c9 in apr_proc_other_child_alert () from /usr/lib/libapr-1.so.0 #7 0x08092202 in ap_mpm_run () #8 0x080673c8 in main () #0 0x00000000 in ?? ()

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bandwidth throttling C linux

- by bob moch

hi im currently creating a function to create a sleep time i can pause between packets for my port scanner im creating for personal/educational use for my home network. what im currently doing is opening /proc/net/dev and reading the 9th set of digits for the eth0 interface to find out the current packets being set and then reading it again and doing some math to figure out a delay to sleep between sending a packet to a port to identify it and fingerprint it. my problem is that no matter what throttle % i use it always seems to send the same rate of packets. i think its mainly my way of mathematically creating my sleep delay. edit:: dont mind the function declaration and the struct stuff all im doing is spawning this function in a thread and passing a pointer to a struct to the function, recreating the struct locally and then freeing the passed structs memory. void *bandwidthmonitor_cmd(void *param) { char cmdline[1024], *bytedata[19]; int i = 0, ii = 0; long long prevbytes = 0, currentbytes = 0, elapsedbytes = 0, byteusage = 0, maxthrottle = 0; command_struct bandwidth = *((command_struct *)param); free(param); //printf("speed: %d\n throttle: %d\n\n", UPLOAD_SPEED, bandwidth.throttle); maxthrottle = UPLOAD_SPEED * bandwidth.throttle / 100; //printf("max throttle:%lld\n", maxthrottle); FILE *f = fopen("/proc/net/dev", "r"); if(f != NULL) { while(1) { while(fgets(cmdline, sizeof(cmdline), f) != NULL) { cmdline[strlen(cmdline)] = '\0'; if(strncmp(cmdline, " eth0", 6) == 0) { bytedata[0] = strtok(cmdline, " "); while(bytedata[i] != NULL) { i++; bytedata[i] = strtok(NULL, " "); } bytedata[i + 1] = '\0'; currentbytes = atoi(bytedata[9]); } } i = 0; rewind(f); elapsedbytes = currentbytes - prevbytes; prevbytes = currentbytes; byteusage = 8 * (elapsedbytes / 1024); //printf("usage:%lld\n",byteusage); if(ii & 0x40) { SLEEP += (maxthrottle - byteusage) * -1.1;//-2.5; if(SLEEP < 0){ SLEEP = 0; } //printf("sleep:%d\n", SLEEP); } usleep(25000); ii++; } } return NULL; } SLEEP and UPLOAD_SPEED are global variables and UPLOAD_SPEED is in kb/s and generated via a speedtest function that gets the upload speed of my computer. this function is running inside a POSIX thread updating SLEEP which my threads doing the socket work grab to sleep by after every packet. as testing instead of only doing the ports i want to check i make it do all the ports over and over again so i can run dstat on a machine to check bandwidth and no matter what bandwidth.throttle is set to it always seems to generate the same amount of bandwidth to the dstat machine. the way i calculate how much i "should" throttle by is by finding the maximum throttle speed which is defined as maxthrottle = upload_speed * throttle / 100; for example if my upload speed was 1000kb/s and my throttle was 90 (90%) my max throttle would be 900kb/s from there it would find the current bytes sent from /proc/net/dev and then find my sleep time via incrementing or decrementing it via sleep += (maxthrottle - bytesysed) * -1.1; this should in theory increase or decrease the sleep time based on how many bytes used there are. the if(ii & 0x40) statement is just for some moderation control. it makes it so it only sets sleep to a new time every 30-40 iterations. final notes: the main problem is that the sleep timer does not seem to modify the speed of packets being set. or maybe its just my implementation because on a freshly restarted machine where /proc/net/dev has low numbers of bytes sent it seems to raise the sleep timer accordingly on my 60kb/s upload machine (ex if i set the throttle to 2 it will incline the sleep timer until network bandwidth out reaches the max bandwidth threshold, but when i try running it on a server which as been online forever it doesnt seem to work as nicely if at all. if anyone can suggest a new method of monitoring the network to adjust a sleep delay then let me know or if anyone sees a flaw in my code. thank you.

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Cannot SSH after resetting firewall on VPS

- by Thomas Buckley

I'm having trouble trying to SSH to my Debian 5 VPS with blacknight. It was working fine until I did the following: Logged into 'Parallels Infrastructure Manager' - Container - Firewall - Set to 'Normal Firewall settings'. It told me there was an error with the IPTables and offered the option again with a checkbox to 'reset' firewall settings, I selected this. I can see that that the default rules are been applied ( anything from anyone on any port and allowing anything to happen). Whenever I attempt to SSH I get the following debug info: thomas@localmachine:~/.ssh$ ssh -v thomas@hostname OpenSSH_5.8p1 Debian-7ubuntu1, OpenSSL 1.0.0e 6 Sep 2011 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to hostname [***********] port 22. debug1: Connection established. debug1: identity file /home/thomas/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-4096 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-4096 debug1: identity file /home/thomas/.ssh/id_rsa-cert type -1 debug1: identity file /home/thomas/.ssh/id_dsa type -1 debug1: identity file /home/thomas/.ssh/id_dsa-cert type -1 debug1: identity file /home/thomas/.ssh/id_ecdsa type -1 debug1: identity file /home/thomas/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-5 debug1: match: OpenSSH_5.1p1 Debian-5 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8p1 Debian-7ubuntu1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA ************************************* debug1: Host 'hostname' is known and matches the RSA host key. debug1: Found key in /home/thomas/.ssh/known_hosts:2 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/thomas/.ssh/id_rsa debug1: Authentications that can continue: publickey debug1: Trying private key: /home/thomas/.ssh/id_dsa debug1: Trying private key: /home/thomas/.ssh/id_ecdsa debug1: No more authentication methods to try. Permission denied (publickey). I had my public/private RSA keys set up and working fine before I reset the firewall settings. I had also made the following changes to my /etc/ssh/sshd_config file on the VPS: PermitRootLogin no PasswordAuthentication no X11Forwarding no UsePAM no UseDNS no AllowUsers thomas Could it be something to do with the SSH server & client having different versions between my local machine and VPS? Any help appreciated. Output with ssh -vvv thomas@localcomputer:~/.ssh$ ssh -vvv thomas@**************** OpenSSH_5.8p1 Debian-7ubuntu1, OpenSSL 1.0.0e 6 Sep 2011 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ************ [*************] port 22. debug1: Connection established. debug3: Incorrect RSA1 identifier debug3: Could not load "/home/thomas/.ssh/id_rsa" as a RSA1 public key debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'Proc-Type:' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'DEK-Info:' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /home/thomas/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-4096 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-4096 debug1: identity file /home/thomas/.ssh/id_rsa-cert type -1 debug1: identity file /home/thomas/.ssh/id_dsa type -1 debug1: identity file /home/thomas/.ssh/id_dsa-cert type -1 debug1: identity file /home/thomas/.ssh/id_ecdsa type -1 debug1: identity file /home/thomas/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-5 debug1: match: OpenSSH_5.1p1 Debian-5 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8p1 Debian-7ubuntu1 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "*****************" from file "/home/thomas/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /home/thomas/.ssh/known_hosts:1 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 127/256 debug2: bits set: 498/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA *********************************************************** debug3: load_hostkeys: loading entries for host "*********************" from file "/home/thomas/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /home/thomas/.ssh/known_hosts:1 debug3: load_hostkeys: loaded 1 keys debug1: Host '****************' is known and matches the RSA host key. debug1: Found key in /home/thomas/.ssh/known_hosts:1 debug2: bits set: 516/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/thomas/.ssh/id_rsa (0x7fa7028b6010) debug2: key: /home/thomas/.ssh/id_dsa ((nil)) debug2: key: /home/thomas/.ssh/id_ecdsa ((nil)) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/thomas/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey debug1: Trying private key: /home/thomas/.ssh/id_dsa debug3: no such identity: /home/thomas/.ssh/id_dsa debug1: Trying private key: /home/thomas/.ssh/id_ecdsa debug3: no such identity: /home/thomas/.ssh/id_ecdsa debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey). sshd_config # Package generated configuration file # See the sshd(8) manpage for details # What ports, IPs and protocols we listen for Port 22 # Use these options to restrict which interfaces/protocols sshd will bind to #ListenAddress :: #ListenAddress 0.0.0.0 Protocol 2 # HostKeys for protocol version 2 HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_dsa_key #Privilege Separation is turned on for security UsePrivilegeSeparation yes # Lifetime and size of ephemeral version 1 server key KeyRegenerationInterval 3600 ServerKeyBits 768 # Logging SyslogFacility AUTH LogLevel INFO # Authentication: LoginGraceTime 120 PermitRootLogin no StrictModes yes RSAAuthentication yes PubkeyAuthentication yes #AuthorizedKeysFile %h/.ssh/authorized_keys # Don't read the user's ~/.rhosts and ~/.shosts files IgnoreRhosts yes # For this to work you will also need host keys in /etc/ssh_known_hosts RhostsRSAAuthentication no # similar for protocol version 2 HostbasedAuthentication no # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication #IgnoreUserKnownHosts yes # To enable empty passwords, change to yes (NOT RECOMMENDED) PermitEmptyPasswords no # Change to yes to enable challenge-response passwords (beware issues with # some PAM modules and threads) C hallengeResponseAuthentication no # Change to no to disable tunnelled clear text passwords PasswordAuthentication no # Kerberos options #KerberosAuthentication no #KerberosGetAFSToken no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes # GSSAPI options #GSSAPIAuthentication no #GSSAPICleanupCredentials yes X11Forwarding no X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes #UseLogin no #MaxStartups 10:30:60 #Banner /etc/issue.net # Allow client to pass locale environment variables AcceptEnv LANG LC_* Subsystem sftp /usr/lib/openssh/sftp-server UsePAM no UseDNS no AllowUsers thomas Thanks

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Sendmail Failing to Forward Locally Addressed Mail to Exchange Server

- by DomainSoil

I've recently gained employment as a web developer with a small company. What they neglected to tell me upon hire was that I would be administrating the server along with my other daily duties. Now, truth be told, I'm not clueless when it comes to these things, but this is my first rodeo working with a rack server/console.. However, I'm confident that I will be able to work through any solutions you provide. Short Description: When a customer places an order via our (Magento CE 1.8.1.0) website, a copy of said order is supposed to be BCC'd to our sales manager. I say supposed because this was a working feature before the old administrator left. Long Description: Shortly after I started, we had a server crash which required a server restart. After restart, we noticed a few features on our site weren't working, but all those have been cleaned up except this one. I had to create an account on our server for root access. When a customer places an order, our sites software (Magento CE 1.8.1.0) is configured to BCC the customers order email to our sales manager. We use a Microsoft Exchange 2007 Server for our mail, which is hosted on a different machine (in-house) that I don't have access to ATM, but I'm sure I could if needed. As far as I can tell, all other external emails work.. Only INTERNAL email addresses fail to deliver. I know this because I've also tested my own internal address via our website. I set up an account with an internal email, made a test order, and never received the email. I changed my email for the account to an external GMail account, and received emails as expected. Let's dive into the logs and config's. For privacy/security reasons, names have been changed to the following: domain.com = Our Top Level Domain. email.local = Our Exchange Server. example.com = ANY other TLD. OLDadmin = Our previous Server Administrator. NEWadmin = Me. SALES@ = Our Sales Manager. Customer# = A Customer. Here's a list of the programs and config files used that hold relevant for this issue: Server: > [root@www ~]# cat /etc/centos-release CentOS release 6.3 (final) Sendmail: > [root@www ~]# sendmail -d0.1 -bt < /dev/null Version 8.14.4 ========SYSTEM IDENTITY (after readcf)======== (short domain name) $w = domain (canonical domain name) $j = domain.com (subdomain name) $m = com (node name) $k = www.domain.com > [root@www ~]# rpm -qa | grep -i sendmail sendmail-cf-8.14.4-8.e16.noarch sendmail-8.14-4-8.e16.x86_64 nslookup: > [root@www ~]# nslookup email.local Name: email.local Address: 192.168.1.50 hostname: > [root@www ~]# hostname www.domain.com /etc/mail/access: > [root@www ~]# vi /etc/mail/access Connect:localhost.localdomain RELAY Connect:localhost RELAY Connect:127.0.0.1 RELAY /etc/mail/domaintable: > [root@www ~]# vi /etc/mail/domaintable # /etc/mail/local-host-names: > [root@www ~]# vi /etc/mail/local-host-names # /etc/mail/mailertable: > [root@www ~]# vi /etc/mail/mailertable # /etc/mail/sendmail.cf: > [root@www ~]# vi /etc/mail/sendmail.cf ###################################################################### ##### ##### DO NOT EDIT THIS FILE! Only edit the source .mc file. ##### ###################################################################### ###################################################################### ##### $Id: cfhead.m4,v 8.120 2009/01/23 22:39:21 ca Exp $ ##### ##### $Id: cf.m4,v 8.32 1999/02/07 07:26:14 gshapiro Exp $ ##### ##### setup for linux ##### ##### $Id: linux.m4,v 8.13 2000/09/17 17:30:00 gshapiro Exp $ ##### ##### $Id: local_procmail.m4,v 8.22 2002/11/17 04:24:19 ca Exp $ ##### ##### $Id: no_default_msa.m4,v 8.2 2001/02/14 05:03:22 gshapiro Exp $ ##### ##### $Id: smrsh.m4,v 8.14 1999/11/18 05:06:23 ca Exp $ ##### ##### $Id: mailertable.m4,v 8.25 2002/06/27 23:23:57 gshapiro Exp $ ##### ##### $Id: virtusertable.m4,v 8.23 2002/06/27 23:23:57 gshapiro Exp $ ##### ##### $Id: redirect.m4,v 8.15 1999/08/06 01:47:36 gshapiro Exp $ ##### ##### $Id: always_add_domain.m4,v 8.11 2000/09/12 22:00:53 ca Exp $ ##### ##### $Id: use_cw_file.m4,v 8.11 2001/08/26 20:58:57 gshapiro Exp $ ##### ##### $Id: use_ct_file.m4,v 8.11 2001/08/26 20:58:57 gshapiro Exp $ ##### ##### $Id: local_procmail.m4,v 8.22 2002/11/17 04:24:19 ca Exp $ ##### ##### $Id: access_db.m4,v 8.27 2006/07/06 21:10:10 ca Exp $ ##### ##### $Id: blacklist_recipients.m4,v 8.13 1999/04/02 02:25:13 gshapiro Exp $ ##### ##### $Id: accept_unresolvable_domains.m4,v 8.10 1999/02/07 07:26:07 gshapiro Exp $ ##### ##### $Id: masquerade_envelope.m4,v 8.9 1999/02/07 07:26:10 gshapiro Exp $ ##### ##### $Id: masquerade_entire_domain.m4,v 8.9 1999/02/07 07:26:10 gshapiro Exp $ ##### ##### $Id: proto.m4,v 8.741 2009/12/11 00:04:53 ca Exp $ ##### # level 10 config file format V10/Berkeley # override file safeties - setting this option compromises system security, # addressing the actual file configuration problem is preferred # need to set this before any file actions are encountered in the cf file #O DontBlameSendmail=safe # default LDAP map specification # need to set this now before any LDAP maps are defined #O LDAPDefaultSpec=-h localhost ################## # local info # ################## # my LDAP cluster # need to set this before any LDAP lookups are done (including classes) #D{sendmailMTACluster}$m Cwlocalhost # file containing names of hosts for which we receive email Fw/etc/mail/local-host-names # my official domain name # ... define this only if sendmail cannot automatically determine your domain #Dj$w.Foo.COM # host/domain names ending with a token in class P are canonical CP. # "Smart" relay host (may be null) DSemail.local # operators that cannot be in local usernames (i.e., network indicators) CO @ % ! # a class with just dot (for identifying canonical names) C.. # a class with just a left bracket (for identifying domain literals) C[[ # access_db acceptance class C{Accept}OK RELAY C{ResOk}OKR # Hosts for which relaying is permitted ($=R) FR-o /etc/mail/relay-domains # arithmetic map Karith arith # macro storage map Kmacro macro # possible values for TLS_connection in access map C{Tls}VERIFY ENCR # who I send unqualified names to if FEATURE(stickyhost) is used # (null means deliver locally) DRemail.local. # who gets all local email traffic # ($R has precedence for unqualified names if FEATURE(stickyhost) is used) DHemail.local. # dequoting map Kdequote dequote # class E: names that should be exposed as from this host, even if we masquerade # class L: names that should be delivered locally, even if we have a relay # class M: domains that should be converted to $M # class N: domains that should not be converted to $M #CL root C{E}root C{w}localhost.localdomain C{M}domain.com # who I masquerade as (null for no masquerading) (see also $=M) DMdomain.com # my name for error messages DnMAILER-DAEMON # Mailer table (overriding domains) Kmailertable hash -o /etc/mail/mailertable.db # Virtual user table (maps incoming users) Kvirtuser hash -o /etc/mail/virtusertable.db CPREDIRECT # Access list database (for spam stomping) Kaccess hash -T<TMPF> -o /etc/mail/access.db # Configuration version number DZ8.14.4 /etc/mail/sendmail.mc: > [root@www ~]# vi /etc/mail/sendmail.mc divert(-1)dnl dnl # dnl # This is the sendmail macro config file for m4. If you make changes to dnl # /etc/mail/sendmail.mc, you will need to regenerate the dnl # /etc/mail/sendmail.cf file by confirming that the sendmail-cf package is dnl # installed and then performing a dnl # dnl # /etc/mail/make dnl # include(`/usr/share/sendmail-cf/m4/cf.m4')dnl VERSIONID(`setup for linux')dnl OSTYPE(`linux')dnl dnl # dnl # Do not advertize sendmail version. dnl # dnl define(`confSMTP_LOGIN_MSG', `$j Sendmail; $b')dnl dnl # dnl # default logging level is 9, you might want to set it higher to dnl # debug the configuration dnl # dnl define(`confLOG_LEVEL', `9')dnl dnl # dnl # Uncomment and edit the following line if your outgoing mail needs to dnl # be sent out through an external mail server: dnl # define(`SMART_HOST', `email.local')dnl dnl # define(`confDEF_USER_ID', ``8:12'')dnl dnl define(`confAUTO_REBUILD')dnl define(`confTO_CONNECT', `1m')dnl define(`confTRY_NULL_MX_LIST', `True')dnl define(`confDONT_PROBE_INTERFACES', `True')dnl define(`PROCMAIL_MAILER_PATH', `/usr/bin/procmail')dnl define(`ALIAS_FILE', `/etc/aliases')dnl define(`STATUS_FILE', `/var/log/mail/statistics')dnl define(`UUCP_MAILER_MAX', `2000000')dnl define(`confUSERDB_SPEC', `/etc/mail/userdb.db')dnl define(`confPRIVACY_FLAGS', `authwarnings,novrfy,noexpn,restrictqrun')dnl define(`confAUTH_OPTIONS', `A')dnl dnl # dnl # The following allows relaying if the user authenticates, and disallows dnl # plaintext authentication (PLAIN/LOGIN) on non-TLS links dnl # dnl define(`confAUTH_OPTIONS', `A p')dnl dnl # dnl # PLAIN is the preferred plaintext authentication method and used by dnl # Mozilla Mail and Evolution, though Outlook Express and other MUAs do dnl # use LOGIN. Other mechanisms should be used if the connection is not dnl # guaranteed secure. dnl # Please remember that saslauthd needs to be running for AUTH. dnl # dnl TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl dnl define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl dnl # dnl # Rudimentary information on creating certificates for sendmail TLS: dnl # cd /etc/pki/tls/certs; make sendmail.pem dnl # Complete usage: dnl # make -C /etc/pki/tls/certs usage dnl # dnl define(`confCACERT_PATH', `/etc/pki/tls/certs')dnl dnl define(`confCACERT', `/etc/pki/tls/certs/ca-bundle.crt')dnl dnl define(`confSERVER_CERT', `/etc/pki/tls/certs/sendmail.pem')dnl dnl define(`confSERVER_KEY', `/etc/pki/tls/certs/sendmail.pem')dnl dnl # dnl # This allows sendmail to use a keyfile that is shared with OpenLDAP's dnl # slapd, which requires the file to be readble by group ldap dnl # dnl define(`confDONT_BLAME_SENDMAIL', `groupreadablekeyfile')dnl dnl # dnl define(`confTO_QUEUEWARN', `4h')dnl dnl define(`confTO_QUEUERETURN', `5d')dnl dnl define(`confQUEUE_LA', `12')dnl dnl define(`confREFUSE_LA', `18')dnl define(`confTO_IDENT', `0')dnl dnl FEATURE(delay_checks)dnl FEATURE(`no_default_msa', `dnl')dnl FEATURE(`smrsh', `/usr/sbin/smrsh')dnl FEATURE(`mailertable', `hash -o /etc/mail/mailertable.db')dnl FEATURE(`virtusertable', `hash -o /etc/mail/virtusertable.db')dnl FEATURE(redirect)dnl FEATURE(always_add_domain)dnl FEATURE(use_cw_file)dnl FEATURE(use_ct_file)dnl dnl # dnl # The following limits the number of processes sendmail can fork to accept dnl # incoming messages or process its message queues to 20.) sendmail refuses dnl # to accept connections once it has reached its quota of child processes. dnl # dnl define(`confMAX_DAEMON_CHILDREN', `20')dnl dnl # dnl # Limits the number of new connections per second. This caps the overhead dnl # incurred due to forking new sendmail processes. May be useful against dnl # DoS attacks or barrages of spam. (As mentioned below, a per-IP address dnl # limit would be useful but is not available as an option at this writing.) dnl # dnl define(`confCONNECTION_RATE_THROTTLE', `3')dnl dnl # dnl # The -t option will retry delivery if e.g. the user runs over his quota. dnl # FEATURE(local_procmail, `', `procmail -t -Y -a $h -d $u')dnl FEATURE(`access_db', `hash -T<TMPF> -o /etc/mail/access.db')dnl FEATURE(`blacklist_recipients')dnl EXPOSED_USER(`root')dnl dnl # dnl # For using Cyrus-IMAPd as POP3/IMAP server through LMTP delivery uncomment dnl # the following 2 definitions and activate below in the MAILER section the dnl # cyrusv2 mailer. dnl # dnl define(`confLOCAL_MAILER', `cyrusv2')dnl dnl define(`CYRUSV2_MAILER_ARGS', `FILE /var/lib/imap/socket/lmtp')dnl dnl # dnl # The following causes sendmail to only listen on the IPv4 loopback address dnl # 127.0.0.1 and not on any other network devices. Remove the loopback dnl # address restriction to accept email from the internet or intranet. dnl # DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl dnl # dnl # The following causes sendmail to additionally listen to port 587 for dnl # mail from MUAs that authenticate. Roaming users who can't reach their dnl # preferred sendmail daemon due to port 25 being blocked or redirected find dnl # this useful. dnl # dnl DAEMON_OPTIONS(`Port=submission, Name=MSA, M=Ea')dnl dnl # dnl # The following causes sendmail to additionally listen to port 465, but dnl # starting immediately in TLS mode upon connecting. Port 25 or 587 followed dnl # by STARTTLS is preferred, but roaming clients using Outlook Express can't dnl # do STARTTLS on ports other than 25. Mozilla Mail can ONLY use STARTTLS dnl # and doesn't support the deprecated smtps; Evolution <1.1.1 uses smtps dnl # when SSL is enabled-- STARTTLS support is available in version 1.1.1. dnl # dnl # For this to work your OpenSSL certificates must be configured. dnl # dnl DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl dnl # dnl # The following causes sendmail to additionally listen on the IPv6 loopback dnl # device. Remove the loopback address restriction listen to the network. dnl # dnl DAEMON_OPTIONS(`port=smtp,Addr=::1, Name=MTA-v6, Family=inet6')dnl dnl # dnl # enable both ipv6 and ipv4 in sendmail: dnl # dnl DAEMON_OPTIONS(`Name=MTA-v4, Family=inet, Name=MTA-v6, Family=inet6') dnl # dnl # We strongly recommend not accepting unresolvable domains if you want to dnl # protect yourself from spam. However, the laptop and users on computers dnl # that do not have 24x7 DNS do need this. dnl # FEATURE(`accept_unresolvable_domains')dnl dnl # dnl FEATURE(`relay_based_on_MX')dnl dnl # dnl # Also accept email sent to "localhost.localdomain" as local email. dnl # LOCAL_DOMAIN(`localhost.localdomain')dnl dnl # dnl # The following example makes mail from this host and any additional dnl # specified domains appear to be sent from mydomain.com dnl # MASQUERADE_AS(`domain.com')dnl dnl # dnl # masquerade not just the headers, but the envelope as well dnl FEATURE(masquerade_envelope)dnl dnl # dnl # masquerade not just @mydomainalias.com, but @*.mydomainalias.com as well dnl # FEATURE(masquerade_entire_domain)dnl dnl # MASQUERADE_DOMAIN(domain.com)dnl dnl MASQUERADE_DOMAIN(localhost.localdomain)dnl dnl MASQUERADE_DOMAIN(mydomainalias.com)dnl dnl MASQUERADE_DOMAIN(mydomain.lan)dnl MAILER(smtp)dnl MAILER(procmail)dnl dnl MAILER(cyrusv2)dnl /etc/mail/trusted-users: > [root@www ~]# vi /etc/mail/trusted-users # /etc/mail/virtusertable: > [root@www ~]# vi /etc/mail/virtusertable [email protected] [email protected] [email protected] [email protected] /etc/hosts: > [root@www ~]# vi /etc/hosts 127.0.0.1 localhost.localdomain localhost ::1 localhost6.localdomain6 localhost6 192.168.1.50 email.local I've only included the "local info" part of sendmail.cf, to save space. If there are any files that I've missed, please advise so I may produce them. Now that that's out of the way, lets look at some entries from /var/log/maillog. The first entry is from an order BEFORE the crash, when the site was working as expected. ##Order 200005374 Aug 5, 2014 7:06:38 AM## Aug 5 07:06:39 www sendmail[26149]: s75C6dqB026149: from=OLDadmin, size=11091, class=0, nrcpts=2, msgid=<[email protected]>, relay=OLDadmin@localhost Aug 5 07:06:39 www sendmail[26150]: s75C6dXe026150: from=<[email protected]>, size=11257, class=0, nrcpts=2, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 07:06:39 www sendmail[26149]: s75C6dqB026149: [email protected],=?utf-8?B?dGhvbWFzICBHaWxsZXNwaWU=?= <[email protected]>, ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71091, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75C6dXe026150 Message accepted for delivery) Aug 5 07:06:40 www sendmail[26152]: s75C6dXe026150: to=<[email protected]>,<[email protected]>, delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=161257, relay=email.local. [192.168.1.50], dsn=2.0.0, stat=Sent ( <[email protected]> Queued mail for delivery) This next entry from maillog is from an order AFTER the crash. ##Order 200005375 Aug 5, 2014 9:45:25 AM## Aug 5 09:45:26 www sendmail[30021]: s75EjQ4O030021: from=OLDadmin, size=11344, class=0, nrcpts=2, msgid=<[email protected]>, relay=OLDadmin@localhost Aug 5 09:45:26 www sendmail[30022]: s75EjQm1030022: <[email protected]>... User unknown Aug 5 09:45:26 www sendmail[30021]: s75EjQ4O030021: [email protected], ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71344, relay=[127.0.0.1] [127.0.0.1], dsn=5.1.1, stat=User unknown Aug 5 09:45:26 www sendmail[30022]: s75EjQm1030022: from=<[email protected]>, size=11500, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 09:45:26 www sendmail[30021]: s75EjQ4O030021: to==?utf-8?B?S2VubmV0aCBCaWViZXI=?= <[email protected]>, ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71344, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75EjQm1030022 Message accepted for delivery) Aug 5 09:45:26 www sendmail[30021]: s75EjQ4O030021: s75EjQ4P030021: DSN: User unknown Aug 5 09:45:26 www sendmail[30022]: s75EjQm3030022: <[email protected]>... User unknown Aug 5 09:45:26 www sendmail[30021]: s75EjQ4P030021: to=OLDadmin, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=42368, relay=[127.0.0.1] [127.0.0.1], dsn=5.1.1, stat=User unknown Aug 5 09:45:26 www sendmail[30022]: s75EjQm3030022: from=<>, size=12368, class=0, nrcpts=0, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 09:45:26 www sendmail[30021]: s75EjQ4P030021: s75EjQ4Q030021: return to sender: User unknown Aug 5 09:45:26 www sendmail[30022]: s75EjQm5030022: from=<>, size=14845, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 09:45:26 www sendmail[30021]: s75EjQ4Q030021: to=postmaster, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=43392, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75EjQm5030022 Message accepted for delivery) Aug 5 09:45:26 www sendmail[30025]: s75EjQm5030022: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=45053, dsn=2.0.0, stat=Sent Aug 5 09:45:27 www sendmail[30024]: s75EjQm1030022: to=<[email protected]>, delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=131500, relay=email.local. [192.168.1.50], dsn=2.0.0, stat=Sent ( <[email protected]> Queued mail for delivery) To add a little more, I think I've pinpointed the actual crash event. ##THE CRASH## Aug 5 09:39:46 www sendmail[3251]: restarting /usr/sbin/sendmail due to signal Aug 5 09:39:46 www sm-msp-queue[3260]: restarting /usr/sbin/sendmail due to signal Aug 5 09:39:46 www sm-msp-queue[29370]: starting daemon (8.14.4): queueing@01:00:00 Aug 5 09:39:47 www sendmail[29372]: starting daemon (8.14.4): SMTP+queueing@01:00:00 Aug 5 09:40:02 www sendmail[29465]: s75Ee2vT029465: Authentication-Warning: www.domain.com: OLDadmin set sender to root using -f Aug 5 09:40:02 www sendmail[29464]: s75Ee2IF029464: Authentication-Warning: www.domain.com: OLDadmin set sender to root using -f Aug 5 09:40:02 www sendmail[29465]: s75Ee2vT029465: from=root, size=1426, class=0, nrcpts=1, msgid=<[email protected]>, relay=OLDadmin@localhost Aug 5 09:40:02 www sendmail[29464]: s75Ee2IF029464: from=root, size=1426, class=0, nrcpts=1, msgid=<[email protected]>, relay=OLDadmin@localhost Aug 5 09:40:02 www sendmail[29466]: s75Ee23t029466: from=<[email protected]>, size=1784, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 09:40:02 www sendmail[29466]: s75Ee23t029466: to=<[email protected]>, delay=00:00:00, mailer=local, pri=31784, dsn=4.4.3, stat=queued Aug 5 09:40:02 www sendmail[29467]: s75Ee2wh029467: from=<[email protected]>, size=1784, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Aug 5 09:40:02 www sendmail[29467]: s75Ee2wh029467: to=<[email protected]>, delay=00:00:00, mailer=local, pri=31784, dsn=4.4.3, stat=queued Aug 5 09:40:02 www sendmail[29464]: s75Ee2IF029464: to=OLDadmin, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31426, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75Ee23t029466 Message accepted for delivery) Aug 5 09:40:02 www sendmail[29465]: s75Ee2vT029465: to=OLDadmin, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31426, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75Ee2wh029467 Message accepted for delivery) Aug 5 09:40:06 www sm-msp-queue[29370]: restarting /usr/sbin/sendmail due to signal Aug 5 09:40:06 www sendmail[29372]: restarting /usr/sbin/sendmail due to signal Aug 5 09:40:06 www sm-msp-queue[29888]: starting daemon (8.14.4): queueing@01:00:00 Aug 5 09:40:06 www sendmail[29890]: starting daemon (8.14.4): SMTP+queueing@01:00:00 Aug 5 09:40:06 www sendmail[29891]: s75Ee23t029466: to=<[email protected]>, delay=00:00:04, mailer=local, pri=121784, dsn=5.1.1, stat=User unknown Aug 5 09:40:06 www sendmail[29891]: s75Ee23t029466: s75Ee6xY029891: DSN: User unknown Aug 5 09:40:06 www sendmail[29891]: s75Ee6xY029891: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=33035, dsn=2.0.0, stat=Sent Aug 5 09:40:06 www sendmail[29891]: s75Ee2wh029467: to=<[email protected]>, delay=00:00:04, mailer=local, pri=121784, dsn=5.1.1, stat=User unknown Aug 5 09:40:06 www sendmail[29891]: s75Ee2wh029467: s75Ee6xZ029891: DSN: User unknown Aug 5 09:40:06 www sendmail[29891]: s75Ee6xZ029891: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=33035, dsn=2.0.0, stat=Sent Something to note about the maillog's: Before the crash, the msgid included localhost.localdomain; after the crash it's been domain.com. Thanks to all who take the time to read and look into this issue. I appreciate it and look forward to tackling this issue together.

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qemu-kvm virtual machine virtio network freeze under load

- by Rick Koshi

I'm having a problem with my virtual machines, where the network will freeze under heavy load. I'm using CentOS 6.2 as both host and guest, not using libvirt, just running qemu-kvm directly as follows: /usr/libexec/qemu-kvm \ -drive file=/data2/vm/rb-dev2-www1-vm.img,index=0,media=disk,cache=none,if=virtio \ -boot order=c \ -m 2G \ -smp cores=1,threads=2 \ -vga std \ -name rb-dev2-www1-vm \ -vnc :84,password \ -net nic,vlan=0,macaddr=52:54:20:00:00:54,model=virtio \ -net tap,vlan=0,ifname=tap84,script=/etc/qemu-ifup \ -monitor unix:/var/run/vm/rb-dev2-www1-vm.mon,server,nowait \ -rtc base=utc \ -device piix3-usb-uhci \ -device usb-tablet /etc/qemu-ifup (used by the above command) is a very simple script, containing the following: #!/bin/sh sudo /sbin/ifconfig $1 0.0.0.0 promisc up sudo /usr/sbin/brctl addif br0 $1 sleep 2 And here's the info on br0 and other interfaces: avl-host3 14# brctl show bridge name bridge id STP enabled interfaces br0 8000.180373f5521a no bond0 tap84 virbr0 8000.525400858961 yes virbr0-nic avl-host3 15# ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: em1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000 link/ether 18:03:73:f5:52:1a brd ff:ff:ff:ff:ff:ff 3: em2: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000 link/ether 18:03:73:f5:52:1a brd ff:ff:ff:ff:ff:ff 4: em3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000 link/ether 18:03:73:f5:52:1e brd ff:ff:ff:ff:ff:ff 5: em4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000 link/ether 18:03:73:f5:52:20 brd ff:ff:ff:ff:ff:ff 6: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP link/ether 18:03:73:f5:52:1a brd ff:ff:ff:ff:ff:ff inet6 fe80::1a03:73ff:fef5:521a/64 scope link valid_lft forever preferred_lft forever 7: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN link/ether 18:03:73:f5:52:1a brd ff:ff:ff:ff:ff:ff inet 172.16.1.46/24 brd 172.16.1.255 scope global br0 inet6 fe80::1a03:73ff:fef5:521a/64 scope link valid_lft forever preferred_lft forever 8: virbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN link/ether 52:54:00:85:89:61 brd ff:ff:ff:ff:ff:ff inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0 9: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 500 link/ether 52:54:00:85:89:61 brd ff:ff:ff:ff:ff:ff 12: tap84: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 500 link/ether ba:e8:9b:2a:ff:48 brd ff:ff:ff:ff:ff:ff inet6 fe80::b8e8:9bff:fe2a:ff48/64 scope link valid_lft forever preferred_lft forever bond0 is a bond of em1 and em2. virbr0 and virbr0-nic are vestigial interfaces left over from CentOS's default installation. They are unused (as far as I know). The guest runs perfectly until I run a large 'rsync', when the network will freeze after some seemingly-random time (usually under a minute). When it freezes, there is no network activity in or out of the guest. I can still connect to the guest's console via vnc, but it is unable to speak out its network interface. Any attempt to 'ping' from the guest gives a "Destination Host Unreachable" error for 3/4 packets and no reply for every fourth packet. Sometimes (perhaps two thirds of the time), I can bring the interface back to life by doing a "service network restart" from the guest's console. If this works (and if I do it before the rsync times out), the rsync will resume. Usually it will freeze again within a minute or two. If I repeat, the rsync will eventually finish, and I presume the machine goes back to waiting for another period of heavy load. Throughout the whole process, there are no console errors or relevant (that I can see) syslog messages on either guest or host machine. If the "service network restart" doesn't work the first time, trying again (and again and again) never seems to work. The command completes normally, with normal output, but the interface stays frozen. However, a soft reboot of the guest machine (without restarting qemu-kvm) always seems to bring it back. I am aware of the "lowest mac address" assignment problem, where the bridge takes on the mac address of the slave interface with the lowest mac address. This causes temporary network freezes, but is definitely not what's happening for me. My freezes are permanent until manual intervention, and you can see from the 'ip addr show' output above that the mac address being used by br0 is that of the physical ethernet. There are no other virtual machines running on the host. I've verified that each virtual machine on the subnet has its own unique mac address. I have rebuilt the guest machine several times, and I have tried this on three different host machines (identical hardware, built identically). Oddly, I do have one virtual host (the second of this series) which never seemed to have a problem. It never had its network freeze when it was running the same rsync during its build. It's particularly odd because it was the second build. The first, on a different host, did have the freezing problem, but the second did not. I assumed at the time that I had done something wrong with the first build, and that the problem was resolved. Unfortunately, the problem reappeared when I built the third VM. Also unfortunately, I can't do many tests with the working VM, as it's now in production use, and I'm hoping I can find the cause of this issue before that machine starts having problems. It's possible that I just got really lucky while running the rsync on the working machine, and that one time it didn't freeze. Of course it's possible that I somehow changed the build scripts without realizing it and re-broke something, but I can't find any such thing. In any case, I'm hoping someone has some idea what could cause this. Addendum: Preliminary tests suggest that I don't have the problem if I substitute e1000 for virtio in the first -net flag to qemu-kvm. I don't consider this a solution, but it is suitable for a stopgap. Has anyone else had (or better yet, solved) this problem with the virtio network driver?

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Failed to convert a wmv file to mp4 with ffmpeg

- by Olaf Erlandsen

i need a help with this command FFMPEG COMMAND: ffmpeg -y -i /input.wmv -vcodec libx264 -acodec libfaac -ac 2 -bufsize 20M -sameq -f mp4 /output.mp4 Output: ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers built on Oct 9 2012 07:04:08 with gcc 4.4.6 (GCC) 20120305 (Red Hat 4.4.6-4) [wmv3 @ 0x16a4800] Extra data: 8 bits left, value: 0 Guessed Channel Layout for Input Stream #0.0 : stereo Input #0, asf, from '/input.wmv': Metadata: WMFSDKVersion : 11.0.5721.5275 WMFSDKNeeded : 0.0.0.0000 IsVBR : 0 Duration: 00:01:35.10, start: 0.000000, bitrate: 496 kb/s Stream #0:0(spa): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, stereo, s16, 64 kb/s Stream #0:1(spa): Video: wmv3 (Main) (WMV3 / 0x33564D57), yuv420p, 320x240, 425 kb/s, SAR 1:1 DAR 4:3, 29.97 tbr, 1k tbn, 1k tbc [libx264 @ 0x16c3000] VBV bufsize set but maxrate unspecified, ignored [libx264 @ 0x16c3000] using SAR=1/1 [libx264 @ 0x16c3000] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 [libx264 @ 0x16c3000] profile High, level 1.3 [libx264 @ 0x16c3000] 264 - core 128 - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00 [wmv3 @ 0x16a4800] Extra data: 8 bits left, value: 0 Output #0, mp4, to '/output.mp4': Metadata: WMFSDKVersion : 11.0.5721.5275 WMFSDKNeeded : 0.0.0.0000 IsVBR : 0 encoder : Lavf54.29.104 Stream #0:0(spa): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 320x240 [SAR 1:1 DAR 4:3], q=-1--1, 30k tbn, 29.97 tbc Stream #0:1(spa): Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, stereo, s16, 128 kb/s Stream mapping: Stream #0:1 -> #0:0 (wmv3 -> libx264) Stream #0:0 -> #0:1 (wmav2 -> libfaac) Press [q] to stop, [?] for help [libfaac @ 0x16b3600] Que input is backward in time [mp4 @ 0x16bb3a0] st:0 PTS: 6174 DTS: 6174 < 7169 invalid, clipping frame= 144 fps=0.0 q=29.0 size= 207kB time=00:00:03.38 bitrate= 500.3kbits/s frame= 259 fps=257 q=29.0 size= 447kB time=00:00:07.30 bitrate= 501.3kbits/s frame= 375 fps=248 q=29.0 size= 668kB time=00:00:11.01 bitrate= 496.5kbits/s frame= 487 fps=241 q=29.0 size= 836kB time=00:00:14.85 bitrate= 460.7kbits/s frame= 605 fps=240 q=29.0 size= 1080kB time=00:00:18.92 bitrate= 467.4kbits/s frame= 719 fps=238 q=29.0 size= 1306kB time=00:00:22.80 bitrate= 469.2kbits/s frame= 834 fps=237 q=29.0 size= 1546kB time=00:00:26.52 bitrate= 477.3kbits/s frame= 953 fps=237 q=29.0 size= 1763kB time=00:00:30.27 bitrate= 477.0kbits/s frame= 1071 fps=237 q=29.0 size= 1986kB time=00:00:34.36 bitrate= 473.4kbits/s frame= 1161 fps=231 q=29.0 size= 2160kB time=00:00:37.21 bitrate= 475.4kbits/s frame= 1221 fps=220 q=29.0 size= 2282kB time=00:00:39.53 bitrate= 472.9kbits/s frame= 1280 fps=212 q=29.0 size= 2392kB time=00:00:41.16 bitrate= 476.1kbits/s frame= 1331 fps=203 q=29.0 size= 2502kB time=00:00:43.23 bitrate= 474.1kbits/s frame= 1379 fps=195 q=29.0 size= 2618kB time=00:00:44.72 bitrate= 479.6kbits/s frame= 1430 fps=189 q=29.0 size= 2733kB time=00:00:46.34 bitrate= 483.0kbits/s frame= 1487 fps=184 q=29.0 size= 2851kB time=00:00:48.40 bitrate= 482.6kbits/s frame= 1546 fps=180 q=26.0 size= 2973kB time=00:00:50.43 bitrate= 482.9kbits/s frame= 1610 fps=177 q=29.0 size= 3112kB time=00:00:52.40 bitrate= 486.5kbits/s frame= 1672 fps=174 q=29.0 size= 3231kB time=00:00:54.35 bitrate= 487.0kbits/s frame= 1733 fps=171 q=29.0 size= 3348kB time=00:00:56.51 bitrate= 485.3kbits/s frame= 1792 fps=169 q=29.0 size= 3459kB time=00:00:58.28 bitrate= 486.2kbits/s frame= 1851 fps=166 q=29.0 size= 3588kB time=00:01:00.32 bitrate= 487.2kbits/s frame= 1910 fps=164 q=29.0 size= 3716kB time=00:01:02.36 bitrate= 488.1kbits/s frame= 1972 fps=162 q=29.0 size= 3833kB time=00:01:04.45 bitrate= 487.1kbits/s frame= 2032 fps=161 q=29.0 size= 3946kB time=00:01:06.40 bitrate= 486.8kbits/s frame= 2091 fps=159 q=29.0 size= 4080kB time=00:01:08.35 bitrate= 488.9kbits/s frame= 2150 fps=158 q=29.0 size= 4201kB time=00:01:10.54 bitrate= 487.9kbits/s frame= 2206 fps=156 q=29.0 size= 4315kB time=00:01:12.39 bitrate= 488.3kbits/s frame= 2263 fps=154 q=29.0 size= 4438kB time=00:01:14.21 bitrate= 489.9kbits/s frame= 2327 fps=154 q=29.0 size= 4567kB time=00:01:16.16 bitrate= 491.2kbits/s frame= 2388 fps=152 q=29.0 size= 4666kB time=00:01:18.48 bitrate= 487.0kbits/s frame= 2450 fps=152 q=29.0 size= 4776kB time=00:01:20.24 bitrate= 487.6kbits/s frame= 2511 fps=151 q=29.0 size= 4890kB time=00:01:22.15 bitrate= 487.6kbits/s frame= 2575 fps=150 q=29.0 size= 5015kB time=00:01:24.42 bitrate= 486.6kbits/s frame= 2635 fps=149 q=29.0 size= 5130kB time=00:01:26.62 bitrate= 485.2kbits/s frame= 2695 fps=148 q=29.0 size= 5258kB time=00:01:28.65 bitrate= 485.9kbits/s frame= 2758 fps=147 q=29.0 size= 5382kB time=00:01:30.64 bitrate= 486.4kbits/s frame= 2816 fps=147 q=29.0 size= 5521kB time=00:01:32.69 bitrate= 487.9kbits/s get_buffer() failed Error while decoding stream #0:0: Invalid argument frame= 2848 fps=143 q=-1.0 Lsize= 5787kB time=00:01:35.10 bitrate= 498.4kbits/s video:5099kB audio:581kB subtitle:0 global headers:0kB muxing overhead 1.884230% [libx264 @ 0x16c3000] frame I:12 Avg QP:22.64 size: 12092 [libx264 @ 0x16c3000] frame P:1508 Avg QP:25.39 size: 2933 [libx264 @ 0x16c3000] frame B:1328 Avg QP:30.62 size: 491 [libx264 @ 0x16c3000] consecutive B-frames: 10.0% 80.8% 8.1% 1.1% [libx264 @ 0x16c3000] mb I I16..4: 1.8% 72.1% 26.0% [libx264 @ 0x16c3000] mb P I16..4: 0.4% 2.4% 0.3% P16..4: 48.3% 19.6% 19.3% 0.0% 0.0% skip: 9.5% [libx264 @ 0x16c3000] mb B I16..4: 0.1% 0.2% 0.0% B16..8: 52.6% 6.6% 2.3% direct: 1.4% skip:36.8% L0:48.8% L1:42.5% BI: 8.7% [libx264 @ 0x16c3000] 8x8 transform intra:75.3% inter:55.4% [libx264 @ 0x16c3000] coded y,uvDC,uvAC intra: 77.9% 81.7% 33.1% inter: 24.2% 11.6% 1.1% [libx264 @ 0x16c3000] i16 v,h,dc,p: 25% 16% 44% 14% [libx264 @ 0x16c3000] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 15% 29% 6% 5% 6% 6% 7% 7% [libx264 @ 0x16c3000] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 20% 15% 17% 7% 9% 8% 9% 7% 7% [libx264 @ 0x16c3000] i8c dc,h,v,p: 50% 19% 24% 7% [libx264 @ 0x16c3000] Weighted P-Frames: Y:3.8% UV:1.1% [libx264 @ 0x16c3000] ref P L0: 75.6% 19.1% 4.2% 1.0% 0.1% [libx264 @ 0x16c3000] ref B L0: 98.1% 1.9% 0.0% [libx264 @ 0x16c3000] ref B L1: 98.9% 1.1% [libx264 @ 0x16c3000] kb/s:439.47 FFMPEG Configuration: --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvpx --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-gpl --enable-postproc --enable-nonfree libavutil 51. 73.101 / 51. 73.101 libavcodec 54. 59.100 / 54. 59.100 libavformat 54. 29.104 / 54. 29.104 libavdevice 54. 2.101 / 54. 2.101 libavfilter 3. 17.100 / 3. 17.100 libswscale 2. 1.101 / 2. 1.101 libswresample 0. 15.100 / 0. 15.100 libpostproc 52. 0.100 / 52. 0.100 PROBLEM #1: [libfaac @ 0x16b3600] Que input is backward in time [mp4 @ 0x16bb3a0] st:0 PTS: 6174 DTS: 6174 < 7169 invalid, clipping PROBLEM #2: get_buffer() failed Error while decoding stream #0:0: Invalid argument

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Use DivX settings to encode to mp4 with ffmpeg

- by sjngm

I'm used to use VirtualDub to encode a video to AVI container with DivX-codec (and MP3 for audio). Now I'm planning to use ffmpeg to encode videos to MP4 container with h264-codec. What I've figured out is that I need to use libx264 and one of those presets to make anything work. However, I'm amazed about the video bitrate ffmpeg uses for encoding. What I currently have is this little batch file: @ECHO OFF SETLOCAL SET IN=source.avs SET FFMPEG_PATH=C:\Program Files (x86)\ffmpeg SET PRESET=-fpre "%FFMPEG_PATH%\presets\libx264-lossless_slow.ffpreset" SET AUDIO=-acodec libmp3lame -ab 128000 SET VIDEO=-vcodec libx264 -vb 1978000 "%FFMPEG_PATH%\ffmpeg.exe" -i %IN% %AUDIO% %VIDEO% %PRESET% test.mp4 ENDLOCAL With this I tell ffmpeg to use 1978k as the bitrate, but ffmpeg uses 15000k+! I tried other presets, but they don't use my specified bitrate. Here are the presets I have: libx264-baseline.ffpreset libx264-ipod320.ffpreset libx264-ipod640.ffpreset libx264-lossless_fast.ffpreset libx264-lossless_max.ffpreset libx264-lossless_medium.ffpreset libx264-lossless_slow.ffpreset libx264-lossless_slower.ffpreset libx264-lossless_ultrafast.ffpreset ffmpeg version: FFmpeg git-N-29181-ga304071 libavutil 50. 40. 1 / 50. 40. 1 libavcodec 52.120. 0 / 52.120. 0 libavformat 52.108. 0 / 52.108. 0 libavdevice 52. 4. 0 / 52. 4. 0 libavfilter 1. 79. 0 / 1. 79. 0 libswscale 0. 13. 0 / 0. 13. 0 Note that I don't use the latest version as it has problems with spaces in filenames. Here's what seems to be the full parameter list DivX 6.9.2 uses: -bvnn 1978000 -vbv 218691200,100663296,100663296 -dir "C:\Users\sjngm\AppData\Roaming\DivX\DivX Codec" -w -b 1 -use_presets=1 -preset=10 -windowed_fullsearch=2 -thread_delay=1 What command line parameters would that be for ffmpeg? EDIT: Going with slhck's suggestion I tried a new 32-bit version. I have no idea if that is 0.9 or newer, I can't find that info. ffmpeg version N-36890-g67f5650 libavutil 51. 34.100 / 51. 34.100 libavcodec 53. 56.105 / 53. 56.105 libavformat 53. 30.100 / 53. 30.100 libavdevice 53. 4.100 / 53. 4.100 libavfilter 2. 59.100 / 2. 59.100 libswscale 2. 1.100 / 2. 1.100 libswresample 0. 6.100 / 0. 6.100 libpostproc 51. 2.100 / 51. 2.100 I reworked my batch file to look like this (interestingly enough I can't find parameter -vprofile in the documentation): @ECHO OFF SETLOCAL SET IN=VTS_01_1.avs SET FFMPEG_PATH=C:\Program Files (x86)\ffmpeg SET PRESET=-vprofile high -preset veryslow SET AUDIO=-acodec libmp3lame -ab 128000 SET VIDEO=-vcodec libx264 -vb 1978000 "%FFMPEG_PATH%\ffmpeg.exe" -i %IN% %AUDIO% %PRESET% %VIDEO% test.mp4 ENDLOCAL I see that it now uses the bitrate properly (thanks to LongNeckbeard for pointing out that the lossless-stuff ignores the bitrate!). Just in case you wonder how I came up with the 1978000, I'm using this formula which I found valid for DivX-files (I'm guessing the bitrate won't change that much for h264): width * height * 25 * 0.22 / 1000 I'm not sure if the 0.22 correlates with the CRF somehow. Overall I forgot to say the I will use a two-pass scenario, which is why I don't use the CRF here. I will try to read more about this. Currently I'm just trying to get something running that shows me that I'm doing something right (ffmpeg isn't the easiest tool to understand ;)). C:\Program Files (x86)\ffmpeg\ffmpeg.exe" -i VTS_01_1.avs -acodec libmp3lame -ab 128000 -vcodec libx264 -vb 1978000 -vprofile high -preset veryslow test.mp4 The output is now: ffmpeg version N-36890-g67f5650 Copyright (c) 2000-2012 the FFmpeg developers built on Jan 16 2012 21:57:13 with gcc 4.6.2 configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib libavutil 51. 34.100 / 51. 34.100 libavcodec 53. 56.105 / 53. 56.105 libavformat 53. 30.100 / 53. 30.100 libavdevice 53. 4.100 / 53. 4.100 libavfilter 2. 59.100 / 2. 59.100 libswscale 2. 1.100 / 2. 1.100 libswresample 0. 6.100 / 0. 6.100 libpostproc 51. 2.100 / 51. 2.100 Input #0, avs, from 'VTS_01_1.avs': Duration: 00:58:46.12, start: 0.000000, bitrate: 0 kb/s Stream #0:0: Video: rawvideo (YV12 / 0x32315659), yuv420p, 576x448, 77414 kb/s, 25 tbr, 25 tbn, 25 tbc Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s File 'test.mp4' already exists. Overwrite ? [y/N] y w:576 h:448 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param: [libx264 @ 05A2C400] using cpu capabilities: MMX2 SSE2Fast FastShuffle SSEMisalign LZCNT [libx264 @ 05A2C400] profile High, level 3.1 [libx264 @ 05A2C400] 264 - core 120 r2120 0c7dab9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=16 deblock=1:0:0 analyse=0x3:0x133 me=umh subme=10 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=24 chroma_me=1 trellis=2 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=8 b_pyramid=2 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=60 rc=abr mbtree=1 bitrate=1978 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00 Output #0, mp4, to 'test.mp4': Metadata: encoder : Lavf53.30.100 Stream #0:0: Video: h264 (![0][0][0] / 0x0021), yuv420p, 576x448, q=-1--1, 1978 kb/s, 25 tbn, 25 tbc Stream #0:1: Audio: mp3 (i[0][0][0] / 0x0069), 48000 Hz, 2 channels, s16, 128 kb/s Stream mapping: Stream #0:0 -> #0:0 (rawvideo -> libx264) Stream #0:1 -> #0:1 (pcm_s16le -> libmp3lame) Press [q] to stop, [?] for help frame= 0 fps= 0 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s frame= 0 fps= 0 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s frame= 0 fps= 0 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s frame= 3 fps= 1 q=22.0 size= 39kB time=00:00:00.04 bitrate=8063.8kbits/ frame= 8 fps= 2 q=22.0 size= 82kB time=00:00:00.24 bitrate=2801.3kbits/ frame= 13 fps= 3 q=23.0 size= 120kB time=00:00:00.44 bitrate=2229.5kbits/ frame= 16 fps= 4 q=23.0 size= 147kB time=00:00:00.56 bitrate=2156.7kbits/ frame= 20 fps= 4 q=22.0 size= 175kB time=00:00:00.72 bitrate=1987.4kbits/ : video:4387kB audio:273kB global headers:0kB muxing overhead 0.260038% [libx264 @ 05A2C400] frame I:2 Avg QP:19.53 size: 29850 [libx264 @ 05A2C400] frame P:76 Avg QP:22.24 size: 19541 [libx264 @ 05A2C400] frame B:359 Avg QP:25.93 size: 8210 [libx264 @ 05A2C400] consecutive B-frames: 0.5% 0.5% 0.0% 8.2% 17.2% 52.2% 16.0% 5.5% 0.0% [libx264 @ 05A2C400] mb I I16..4: 5.4% 75.3% 19.3% [libx264 @ 05A2C400] mb P I16..4: 1.3% 16.5% 2.2% P16..4: 36.3% 28.6% 12.7% 1.8% 0.2% skip: 0.4% [libx264 @ 05A2C400] mb B I16..4: 0.4% 3.8% 0.3% B16..8: 40.0% 18.4% 4.7% direct:18.5% skip:13.9% L0:45.4% L1:38.1% BI:16.5% [libx264 @ 05A2C400] final ratefactor: 20.35 [libx264 @ 05A2C400] 8x8 transform intra:83.1% inter:68.5% [libx264 @ 05A2C400] direct mvs spatial:99.2% temporal:0.8% [libx264 @ 05A2C400] coded y,uvDC,uvAC intra: 64.9% 83.4% 49.2% inter: 49.0% 50.4% 4.4% [libx264 @ 05A2C400] i16 v,h,dc,p: 25% 22% 27% 26% [libx264 @ 05A2C400] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 10% 7% 23% 9% 10% 10% 10%10% 13% [libx264 @ 05A2C400] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 12% 11% 13% 9% 12% 11% 10% 9% 12% [libx264 @ 05A2C400] i8c dc,h,v,p: 42% 28% 16% 14% [libx264 @ 05A2C400] Weighted P-Frames: Y:18.4% UV:7.9% [libx264 @ 05A2C400] ref P L0: 29.1% 11.3% 15.7% 7.3% 6.9% 4.9% 5.1% 3.4%3.9% 2.7% 2.8% 1.8% 1.7% 1.2% 1.4% 0.9% [libx264 @ 05A2C400] ref B L0: 68.8% 11.4% 5.5% 2.9% 2.3% 1.9% 1.5% 1.1%1.1% 1.0% 0.9% 0.7% 0.5% 0.3% 0.1% [libx264 @ 05A2C400] ref B L1: 91.9% 8.1% [libx264 @ 05A2C400] kb/s:2055.88 As far as I'm concerned it doesn't look that bad to me.

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C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

- by James Michael Hare

Once again we consider some of the lesser known classes and keywords of C#. In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>. Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>. Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework. And out of this framework emerged the System.Collections namespace, and it was good. It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections. The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever! With generics the C# language finally got an equivalent of the very powerful C++ templates. As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections. The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on. The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well. So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them. The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required. Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11: 12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20: 21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner. Looking at today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes. With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe. This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations. Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5: 6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9: 10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17: 18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock. With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level). So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently! For example, what if you have a Dictionary that has frequent reads but in-frequent updates? Do you want to lock down the entire Dictionary for every access? This would be overkill and would prevent concurrent reads. In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell). This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in. The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null. Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to. Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic. For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty! This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models. I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts. Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration). Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container. If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations. This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2: 3: // adding to stack is much the same as before 4: stack.Push("First"); 5: 6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek(). This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed. Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items. Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6: 7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10: 11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call. That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call. This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2: 3: // adding to stack is much the same as before 4: stack.Push("First"); 5: 6: var results = stack.GetEnumerator(); 7: 8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10: 11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct. You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all. In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class. The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays. Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart. Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count. This results overall in a O(1) complexity which is quite good. It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2: 3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue. There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue(). Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results. Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2: 3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: 6: var iterator = queue.GetEnumerator(); 7: 8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10: 11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious. Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation. This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5: 6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12: 13: results.Enqueue(result); 14: }); 15: 16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here. Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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ASP.NET Frameworks and Raw Throughput Performance

- by Rick Strahl

A few days ago I had a curious thought: With all these different technologies that the ASP.NET stack has to offer, what's the most efficient technology overall to return data for a server request? When I started this it was mere curiosity rather than a real practical need or result. Different tools are used for different problems and so performance differences are to be expected. But still I was curious to see how the various technologies performed relative to each just for raw throughput of the request getting to the endpoint and back out to the client with as little processing in the actual endpoint logic as possible (aka Hello World!). I want to clarify that this is merely an informal test for my own curiosity and I'm sharing the results and process here because I thought it was interesting. It's been a long while since I've done any sort of perf testing on ASP.NET, mainly because I've not had extremely heavy load requirements and because overall ASP.NET performs very well even for fairly high loads so that often it's not that critical to test load performance. This post is not meant to make a point or even come to a conclusion which tech is better, but just to act as a reference to help understand some of the differences in perf and give a starting point to play around with this yourself. I've included the code for this simple project, so you can play with it and maybe add a few additional tests for different things if you like. Source Code on GitHub I looked at this data for these technologies: ASP.NET Web API ASP.NET MVC WebForms ASP.NET WebPages ASMX AJAX Services (couldn't get AJAX/JSON to run on IIS8 ) WCF Rest Raw ASP.NET HttpHandlers It's quite a mixed bag, of course and the technologies target different types of development. What started out as mere curiosity turned into a bit of a head scratcher as the results were sometimes surprising. What I describe here is more to satisfy my curiosity more than anything and I thought it interesting enough to discuss on the blog :-) First test: Raw Throughput The first thing I did is test raw throughput for the various technologies. This is the least practical test of course since you're unlikely to ever create the equivalent of a 'Hello World' request in a real life application. The idea here is to measure how much time a 'NOP' request takes to return data to the client. So for this request I create the simplest Hello World request that I could come up for each tech. Http Handler The first is the lowest level approach which is an HTTP handler. public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public bool IsReusable { get { return true; } } } WebForms Next I added a couple of ASPX pages - one using CodeBehind and one using only a markup page. The CodeBehind page simple does this in CodeBehind without any markup in the ASPX page: public partial class HelloWorld_CodeBehind : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("Hello World. Time is: " + DateTime.Now.ToString() ); Response.End(); } } while the Markup page only contains some static output via an expression:<%@ Page Language="C#" AutoEventWireup="false" CodeBehind="HelloWorld_Markup.aspx.cs" Inherits="AspNetFrameworksPerformance.HelloWorld_Markup" %> Hello World. Time is <%= DateTime.Now %> ASP.NET WebPages WebPages is the freestanding Razor implementation of ASP.NET. Here's the simple HelloWorld.cshtml page:Hello World @DateTime.Now WCF REST WCF REST was the token REST implementation for ASP.NET before WebAPI and the inbetween step from ASP.NET AJAX. I'd like to forget that this technology was ever considered for production use, but I'll include it here. Here's an OperationContract class: [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World" + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } } WCF REST can return arbitrary results by returning a Stream object and a content type. The code above turns the string result into a stream and returns that back to the client. ASP.NET AJAX (ASMX Services) I also wanted to test ASP.NET AJAX services because prior to WebAPI this is probably still the most widely used AJAX technology for the ASP.NET stack today. Unfortunately I was completely unable to get this running on my Windows 8 machine. Visual Studio 2012 removed adding of ASP.NET AJAX services, and when I tried to manually add the service and configure the script handler references it simply did not work - I always got a SOAP response for GET and POST operations. No matter what I tried I always ended up getting XML results even when explicitly adding the ScriptHandler. So, I didn't test this (but the code is there - you might be able to test this on a Windows 7 box). ASP.NET MVC Next up is probably the most popular ASP.NET technology at the moment: MVC. Here's the small controller: public class MvcPerformanceController : Controller { public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } } ASP.NET WebAPI Next up is WebAPI which looks kind of similar to MVC. Except here I have to use a StringContent result to return the response: public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } } Testing Take a minute to think about each of the technologies… and take a guess which you think is most efficient in raw throughput. The fastest should be pretty obvious, but the others - maybe not so much. The testing I did is pretty informal since it was mainly to satisfy my curiosity - here's how I did this: I used Apache Bench (ab.exe) from a full Apache HTTP installation to run and log the test results of hitting the server. ab.exe is a small executable that lets you hit a URL repeatedly and provides counter information about the number of requests, requests per second etc. ab.exe and the batch file are located in the \LoadTests folder of the project. An ab.exe command line looks like this: ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld which hits the specified URL 100,000 times with a load factor of 20 concurrent requests. This results in output like this: It's a great way to get a quick and dirty performance summary. Run it a few times to make sure there's not a large amount of varience. You might also want to do an IISRESET to clear the Web Server. Just make sure you do a short test run to warm up the server first - otherwise your first run is likely to be skewed downwards. ab.exe also allows you to specify headers and provide POST data and many other things if you want to get a little more fancy. Here all tests are GET requests to keep it simple. I ran each test: 100,000 iterations Load factor of 20 concurrent connections IISReset before starting A short warm up run for API and MVC to make sure startup cost is mitigated Here is the batch file I used for the test: IISRESET REM make sure you add REM C:\Program Files (x86)\Apache Software Foundation\Apache2.2\bin REM to your path so ab.exe can be found REM Warm up ab.exe -n100 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJsonab.exe -n100 -c20 http://localhost/aspnetperf/api/HelloWorldJson ab.exe -n100 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld ab.exe -n100000 -c20 http://localhost/aspnetperf/handler.ashx > handler.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_CodeBehind.aspx > AspxCodeBehind.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_Markup.aspx > AspxMarkup.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld > Wcf.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldCode > Mvc.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld > WebApi.txt I ran each of these tests 3 times and took the average score for Requests/second, with the machine otherwise idle. I did see a bit of variance when running many tests but the values used here are the medians. Part of this has to do with the fact I ran the tests on my local machine - result would probably more consistent running the load test on a separate machine hitting across the network. I ran these tests locally on my laptop which is a Dell XPS with quad core Sandibridge I7-2720QM @ 2.20ghz and a fast SSD drive on Windows 8. CPU load during tests ran to about 70% max across all 4 cores (IOW, it wasn't overloading the machine). Ideally you can try running these tests on a separate machine hitting the local machine. If I remember correctly IIS 7 and 8 on client OSs don't throttle so the performance here should be Results Ok, let's cut straight to the chase. Below are the results from the tests… It's not surprising that the handler was fastest. But it was a bit surprising to me that the next fastest was WebForms and especially Web Forms with markup over a CodeBehind page. WebPages also fared fairly well. MVC and WebAPI are a little slower and the slowest by far is WCF REST (which again I find surprising). As mentioned at the start the raw throughput tests are not overly practical as they don't test scripting performance for the HTML generation engines or serialization performances of the data engines. All it really does is give you an idea of the raw throughput for the technology from time of request to reaching the endpoint and returning minimal text data back to the client which indicates full round trip performance. But it's still interesting to see that Web Forms performs better in throughput than either MVC, WebAPI or WebPages. It'd be interesting to try this with a few pages that actually have some parsing logic on it, but that's beyond the scope of this throughput test. But what's also amazing about this test is the sheer amount of traffic that a laptop computer is handling. Even the slowest tech managed 5700 requests a second, which is one hell of a lot of requests if you extrapolate that out over a 24 hour period. Remember these are not static pages, but dynamic requests that are being served. Another test - JSON Data Service Results The second test I used a JSON result from several of the technologies. I didn't bother running WebForms and WebPages through this test since that doesn't make a ton of sense to return data from the them (OTOH, returning text from the APIs didn't make a ton of sense either :-) In these tests I have a small Person class that gets serialized and then returned to the client. The Person class looks like this: public class Person { public Person() { Id = 10; Name = "Rick"; Entered = DateTime.Now; } public int Id { get; set; } public string Name { get; set; } public DateTime Entered { get; set; } } Here are the updated handler classes that use Person: Handler public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { var action = context.Request.QueryString["action"]; if (action == "json") JsonRequest(context); else TextRequest(context); } public void TextRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public void JsonRequest(HttpContext context) { var json = JsonConvert.SerializeObject(new Person(), Formatting.None); context.Response.ContentType = "application/json"; context.Response.Write(json); } public bool IsReusable { get { return true; } } } This code adds a little logic to check for a action query string and route the request to an optional JSON result method. To generate JSON, I'm using the same JSON.NET serializer (JsonConvert.SerializeObject) used in Web API to create the JSON response. WCF REST [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World " + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } [OperationContract] [WebGet(ResponseFormat=WebMessageFormat.Json,BodyStyle=WebMessageBodyStyle.WrappedRequest)] public Person HelloWorldJson() { // Add your operation implementation here return new Person(); } } For WCF REST all I have to do is add a method with the Person result type. ASP.NET MVC public class MvcPerformanceController : Controller { // // GET: /MvcPerformance/ public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } public JsonResult HelloWorldJson() { return Json(new Person(), JsonRequestBehavior.AllowGet); } } For MVC all I have to do for a JSON response is return a JSON result. ASP.NET internally uses JavaScriptSerializer. ASP.NET WebAPI public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } [HttpGet] public Person HelloWorldJson() { return new Person(); } [HttpGet] public HttpResponseMessage HelloWorldJson2() { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Content = new ObjectContent<Person>(new Person(), GlobalConfiguration.Configuration.Formatters.JsonFormatter); return response; } } Testing and Results To run these data requests I used the following ab.exe commands:REM JSON RESPONSES ab.exe -n100000 -c20 http://localhost/aspnetperf/Handler.ashx?action=json > HandlerJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJson > MvcJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorldJson > WebApiJson.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorldJson > WcfJson.txt The results from this test run are a bit interesting in that the WebAPI test improved performance significantly over returning plain string content. Here are the results: The performance for each technology drops a little bit except for WebAPI which is up quite a bit! From this test it appears that WebAPI is actually significantly better performing returning a JSON response, rather than a plain string response. Snag with Apache Benchmark and 'Length Failures' I ran into a little snag with Apache Benchmark, which was reporting failures for my Web API requests when serializing. As the graph shows performance improved significantly from with JSON results from 5580 to 6530 or so which is a 15% improvement (while all others slowed down by 3-8%). However, I was skeptical at first because the WebAPI test reports showed a bunch of errors on about 10% of the requests. Check out this report: Notice the Failed Request count. What the hey? Is WebAPI failing on roughly 10% of requests when sending JSON? Turns out: No it's not! But it took some sleuthing to figure out why it reports these failures. At first I thought that Web API was failing, and so to make sure I re-ran the test with Fiddler attached and runiisning the ab.exe test by using the -X switch: ab.exe -n100 -c10 -X localhost:8888 http://localhost/aspnetperf/api/HelloWorldJson which showed that indeed all requests where returning proper HTTP 200 results with full content. However ab.exe was reporting the errors. After some closer inspection it turned out that the dates varying in size altered the response length in dynamic output. For example: these two results: {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.841926-10:00"} {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.8519262-10:00"} are different in length for the number which results in 68 and 69 bytes respectively. The same URL produces different result lengths which is what ab.exe reports. I didn't notice at first bit the same is happening when running the ASHX handler with JSON.NET result since it uses the same serializer that varies the milliseconds. Moral: You can typically ignore Length failures in Apache Benchmark and when in doubt check the actual output with Fiddler. Note that the other failure values are accurate though. Another interesting Side Note: Perf drops over Time As I was running these tests repeatedly I was finding that performance steadily dropped from a startup peak to a 10-15% lower stable level. IOW, with Web API I'd start out with around 6500 req/sec and in subsequent runs it keeps dropping until it would stabalize somewhere around 5900 req/sec occasionally jumping lower. For these tests this is why I did the IIS RESET and warm up for individual tests. This is a little puzzling. Looking at Process Monitor while the test are running memory very quickly levels out as do handles and threads, on the first test run. Subsequent runs everything stays stable, but the performance starts going downwards. This applies to all the technologies - Handlers, Web Forms, MVC, Web API - curious to see if others test this and see similar results. Doing an IISRESET then resets everything and performance starts off at peak again… Summary As I stated at the outset, these were informal to satiate my curiosity not to prove that any technology is better or even faster than another. While there clearly are differences in performance the differences (other than WCF REST which was by far the slowest and the raw handler which was by far the highest) are relatively minor, so there is no need to feel that any one technology is a runaway standout in raw performance. Choosing a technology is about more than pure performance but also about the adequateness for the job and the easy of implementation. The strengths of each technology will make for any minor performance difference we see in these tests. However, to me it's important to get an occasional reality check and compare where new technologies are heading. Often times old stuff that's been optimized and designed for a time of less horse power can utterly blow the doors off newer tech and simple checks like this let you compare. Luckily we're seeing that much of the new stuff performs well even in V1.0 which is great. To me it was very interesting to see Web API perform relatively badly with plain string content, which originally led me to think that Web API might not be properly optimized just yet. For those that caught my Tweets late last week regarding WebAPI's slow responses was with String content which is in fact considerably slower. Luckily where it counts with serialized JSON and XML WebAPI actually performs better. But I do wonder what would make generic string content slower than serialized code? This stresses another point: Don't take a single test as the final gospel and don't extrapolate out from a single set of tests. Certainly Twitter can make you feel like a fool when you post something immediate that hasn't been fleshed out a little more <blush>. Egg on my face. As a result I ended up screwing around with this for a few hours today to compare different scenarios. Well worth the time… I hope you found this useful, if not for the results, maybe for the process of quickly testing a few requests for performance and charting out a comparison. Now onwards with more serious stuff… Resources Source Code on GitHub Apache HTTP Server Project (ab.exe is part of the binary distribution)© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET Web Api Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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Advanced TSQL Tuning: Why Internals Knowledge Matters

- by Paul White

There is much more to query tuning than reducing logical reads and adding covering nonclustered indexes. Query tuning is not complete as soon as the query returns results quickly in the development or test environments. In production, your query will compete for memory, CPU, locks, I/O and other resources on the server. Today’s entry looks at some tuning considerations that are often overlooked, and shows how deep internals knowledge can help you write better TSQL. As always, we’ll need some example data. In fact, we are going to use three tables today, each of which is structured like this: Each table has 50,000 rows made up of an INTEGER id column and a padding column containing 3,999 characters in every row. The only difference between the three tables is in the type of the padding column: the first table uses CHAR(3999), the second uses VARCHAR(MAX), and the third uses the deprecated TEXT type. A script to create a database with the three tables and load the sample data follows: USE master; GO IF DB_ID('SortTest') IS NOT NULL DROP DATABASE SortTest; GO CREATE DATABASE SortTest COLLATE LATIN1_GENERAL_BIN; GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest', SIZE = 3GB, MAXSIZE = 3GB ); GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest_log', SIZE = 256MB, MAXSIZE = 1GB, FILEGROWTH = 128MB ); GO ALTER DATABASE SortTest SET ALLOW_SNAPSHOT_ISOLATION OFF ; ALTER DATABASE SortTest SET AUTO_CLOSE OFF ; ALTER DATABASE SortTest SET AUTO_CREATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_SHRINK OFF ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS_ASYNC ON ; ALTER DATABASE SortTest SET PARAMETERIZATION SIMPLE ; ALTER DATABASE SortTest SET READ_COMMITTED_SNAPSHOT OFF ; ALTER DATABASE SortTest SET MULTI_USER ; ALTER DATABASE SortTest SET RECOVERY SIMPLE ; USE SortTest; GO CREATE TABLE dbo.TestCHAR ( id INTEGER IDENTITY (1,1) NOT NULL, padding CHAR(3999) NOT NULL, CONSTRAINT [PK dbo.TestCHAR (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestMAX ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL, CONSTRAINT [PK dbo.TestMAX (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestTEXT ( id INTEGER IDENTITY (1,1) NOT NULL, padding TEXT NOT NULL, CONSTRAINT [PK dbo.TestTEXT (id)] PRIMARY KEY CLUSTERED (id), ) ; -- ============= -- Load TestCHAR (about 3s) -- ============= INSERT INTO dbo.TestCHAR WITH (TABLOCKX) ( padding ) SELECT padding = REPLICATE(CHAR(65 + (Data.n % 26)), 3999) FROM ( SELECT TOP (50000) n = ROW_NUMBER() OVER (ORDER BY (SELECT 0)) - 1 FROM master.sys.columns C1, master.sys.columns C2, master.sys.columns C3 ORDER BY n ASC ) AS Data ORDER BY Data.n ASC ; -- ============ -- Load TestMAX (about 3s) -- ============ INSERT INTO dbo.TestMAX WITH (TABLOCKX) ( padding ) SELECT CONVERT(VARCHAR(MAX), padding) FROM dbo.TestCHAR ORDER BY id ; -- ============= -- Load TestTEXT (about 5s) -- ============= INSERT INTO dbo.TestTEXT WITH (TABLOCKX) ( padding ) SELECT CONVERT(TEXT, padding) FROM dbo.TestCHAR ORDER BY id ; -- ========== -- Space used -- ========== -- EXECUTE sys.sp_spaceused @objname = 'dbo.TestCHAR'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAX'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestTEXT'; ; CHECKPOINT ; That takes around 15 seconds to run, and shows the space allocated to each table in its output: To illustrate the points I want to make today, the example task we are going to set ourselves is to return a random set of 150 rows from each table. The basic shape of the test query is the same for each of the three test tables: SELECT TOP (150) T.id, T.padding FROM dbo.Test AS T ORDER BY NEWID() OPTION (MAXDOP 1) ; Test 1 – CHAR(3999) Running the template query shown above using the TestCHAR table as the target, we find that the query takes around 5 seconds to return its results. This seems slow, considering that the table only has 50,000 rows. Working on the assumption that generating a GUID for each row is a CPU-intensive operation, we might try enabling parallelism to see if that speeds up the response time. Running the query again (but without the MAXDOP 1 hint) on a machine with eight logical processors, the query now takes 10 seconds to execute – twice as long as when run serially. Rather than attempting further guesses at the cause of the slowness, let’s go back to serial execution and add some monitoring. The script below monitors STATISTICS IO output and the amount of tempdb used by the test query. We will also run a Profiler trace to capture any warnings generated during query execution. DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TC.id, TC.padding FROM dbo.TestCHAR AS TC ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; Let’s take a closer look at the statistics and query plan generated from this: Following the flow of the data from right to left, we see the expected 50,000 rows emerging from the Clustered Index Scan, with a total estimated size of around 191MB. The Compute Scalar adds a column containing a random GUID (generated from the NEWID() function call) for each row. With this extra column in place, the size of the data arriving at the Sort operator is estimated to be 192MB. Sort is a blocking operator – it has to examine all of the rows on its input before it can produce its first row of output (the last row received might sort first). This characteristic means that Sort requires a memory grant – memory allocated for the query’s use by SQL Server just before execution starts. In this case, the Sort is the only memory-consuming operator in the plan, so it has access to the full 243MB (248,696KB) of memory reserved by SQL Server for this query execution. Notice that the memory grant is significantly larger than the expected size of the data to be sorted. SQL Server uses a number of techniques to speed up sorting, some of which sacrifice size for comparison speed. Sorts typically require a very large number of comparisons, so this is usually a very effective optimization. One of the drawbacks is that it is not possible to exactly predict the sort space needed, as it depends on the data itself. SQL Server takes an educated guess based on data types, sizes, and the number of rows expected, but the algorithm is not perfect. In spite of the large memory grant, the Profiler trace shows a Sort Warning event (indicating that the sort ran out of memory), and the tempdb usage monitor shows that 195MB of tempdb space was used – all of that for system use. The 195MB represents physical write activity on tempdb, because SQL Server strictly enforces memory grants – a query cannot ‘cheat’ and effectively gain extra memory by spilling to tempdb pages that reside in memory. Anyway, the key point here is that it takes a while to write 195MB to disk, and this is the main reason that the query takes 5 seconds overall. If you are wondering why using parallelism made the problem worse, consider that eight threads of execution result in eight concurrent partial sorts, each receiving one eighth of the memory grant. The eight sorts all spilled to tempdb, resulting in inefficiencies as the spilled sorts competed for disk resources. More importantly, there are specific problems at the point where the eight partial results are combined, but I’ll cover that in a future post. CHAR(3999) Performance Summary: 5 seconds elapsed time 243MB memory grant 195MB tempdb usage 192MB estimated sort set 25,043 logical reads Sort Warning Test 2 – VARCHAR(MAX) We’ll now run exactly the same test (with the additional monitoring) on the table using a VARCHAR(MAX) padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TM.id, TM.padding FROM dbo.TestMAX AS TM ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query takes around 8 seconds to complete (3 seconds longer than Test 1). Notice that the estimated row and data sizes are very slightly larger, and the overall memory grant has also increased very slightly to 245MB. The most marked difference is in the amount of tempdb space used – this query wrote almost 391MB of sort run data to the physical tempdb file. Don’t draw any general conclusions about VARCHAR(MAX) versus CHAR from this – I chose the length of the data specifically to expose this edge case. In most cases, VARCHAR(MAX) performs very similarly to CHAR – I just wanted to make test 2 a bit more exciting. MAX Performance Summary: 8 seconds elapsed time 245MB memory grant 391MB tempdb usage 193MB estimated sort set 25,043 logical reads Sort warning Test 3 – TEXT The same test again, but using the deprecated TEXT data type for the padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TT.id, TT.padding FROM dbo.TestTEXT AS TT ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query runs in 500ms. If you look at the metrics we have been checking so far, it’s not hard to understand why: TEXT Performance Summary: 0.5 seconds elapsed time 9MB memory grant 5MB tempdb usage 5MB estimated sort set 207 logical reads 596 LOB logical reads Sort warning SQL Server’s memory grant algorithm still underestimates the memory needed to perform the sorting operation, but the size of the data to sort is so much smaller (5MB versus 193MB previously) that the spilled sort doesn’t matter very much. Why is the data size so much smaller? The query still produces the correct results – including the large amount of data held in the padding column – so what magic is being performed here? TEXT versus MAX Storage The answer lies in how columns of the TEXT data type are stored. By default, TEXT data is stored off-row in separate LOB pages – which explains why this is the first query we have seen that records LOB logical reads in its STATISTICS IO output. You may recall from my last post that LOB data leaves an in-row pointer to the separate storage structure holding the LOB data. SQL Server can see that the full LOB value is not required by the query plan until results are returned, so instead of passing the full LOB value down the plan from the Clustered Index Scan, it passes the small in-row structure instead. SQL Server estimates that each row coming from the scan will be 79 bytes long – 11 bytes for row overhead, 4 bytes for the integer id column, and 64 bytes for the LOB pointer (in fact the pointer is rather smaller – usually 16 bytes – but the details of that don’t really matter right now). OK, so this query is much more efficient because it is sorting a very much smaller data set – SQL Server delays retrieving the LOB data itself until after the Sort starts producing its 150 rows. The question that normally arises at this point is: Why doesn’t SQL Server use the same trick when the padding column is defined as VARCHAR(MAX)? The answer is connected with the fact that if the actual size of the VARCHAR(MAX) data is 8000 bytes or less, it is usually stored in-row in exactly the same way as for a VARCHAR(8000) column – MAX data only moves off-row into LOB storage when it exceeds 8000 bytes. The default behaviour of the TEXT type is to be stored off-row by default, unless the ‘text in row’ table option is set suitably and there is room on the page. There is an analogous (but opposite) setting to control the storage of MAX data – the ‘large value types out of row’ table option. By enabling this option for a table, MAX data will be stored off-row (in a LOB structure) instead of in-row. SQL Server Books Online has good coverage of both options in the topic In Row Data. The MAXOOR Table The essential difference, then, is that MAX defaults to in-row storage, and TEXT defaults to off-row (LOB) storage. You might be thinking that we could get the same benefits seen for the TEXT data type by storing the VARCHAR(MAX) values off row – so let’s look at that option now. This script creates a fourth table, with the VARCHAR(MAX) data stored off-row in LOB pages: CREATE TABLE dbo.TestMAXOOR ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL, CONSTRAINT [PK dbo.TestMAXOOR (id)] PRIMARY KEY CLUSTERED (id), ) ; EXECUTE sys.sp_tableoption @TableNamePattern = N'dbo.TestMAXOOR', @OptionName = 'large value types out of row', @OptionValue = 'true' ; SELECT large_value_types_out_of_row FROM sys.tables WHERE [schema_id] = SCHEMA_ID(N'dbo') AND name = N'TestMAXOOR' ; INSERT INTO dbo.TestMAXOOR WITH (TABLOCKX) ( padding ) SELECT SPACE(0) FROM dbo.TestCHAR ORDER BY id ; UPDATE TM WITH (TABLOCK) SET padding.WRITE (TC.padding, NULL, NULL) FROM dbo.TestMAXOOR AS TM JOIN dbo.TestCHAR AS TC ON TC.id = TM.id ; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAXOOR' ; CHECKPOINT ; Test 4 – MAXOOR We can now re-run our test on the MAXOOR (MAX out of row) table: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) MO.id, MO.padding FROM dbo.TestMAXOOR AS MO ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; TEXT Performance Summary: 0.3 seconds elapsed time 245MB memory grant 0MB tempdb usage 193MB estimated sort set 207 logical reads 446 LOB logical reads No sort warning The query runs very quickly – slightly faster than Test 3, and without spilling the sort to tempdb (there is no sort warning in the trace, and the monitoring query shows zero tempdb usage by this query). SQL Server is passing the in-row pointer structure down the plan and only looking up the LOB value on the output side of the sort. The Hidden Problem There is still a huge problem with this query though – it requires a 245MB memory grant. No wonder the sort doesn’t spill to tempdb now – 245MB is about 20 times more memory than this query actually requires to sort 50,000 records containing LOB data pointers. Notice that the estimated row and data sizes in the plan are the same as in test 2 (where the MAX data was stored in-row). The optimizer assumes that MAX data is stored in-row, regardless of the sp_tableoption setting ‘large value types out of row’. Why? Because this option is dynamic – changing it does not immediately force all MAX data in the table in-row or off-row, only when data is added or actually changed. SQL Server does not keep statistics to show how much MAX or TEXT data is currently in-row, and how much is stored in LOB pages. This is an annoying limitation, and one which I hope will be addressed in a future version of the product. So why should we worry about this? Excessive memory grants reduce concurrency and may result in queries waiting on the RESOURCE_SEMAPHORE wait type while they wait for memory they do not need. 245MB is an awful lot of memory, especially on 32-bit versions where memory grants cannot use AWE-mapped memory. Even on a 64-bit server with plenty of memory, do you really want a single query to consume 0.25GB of memory unnecessarily? That’s 32,000 8KB pages that might be put to much better use. The Solution The answer is not to use the TEXT data type for the padding column. That solution happens to have better performance characteristics for this specific query, but it still results in a spilled sort, and it is hard to recommend the use of a data type which is scheduled for removal. I hope it is clear to you that the fundamental problem here is that SQL Server sorts the whole set arriving at a Sort operator. Clearly, it is not efficient to sort the whole table in memory just to return 150 rows in a random order. The TEXT example was more efficient because it dramatically reduced the size of the set that needed to be sorted. We can do the same thing by selecting 150 unique keys from the table at random (sorting by NEWID() for example) and only then retrieving the large padding column values for just the 150 rows we need. The following script implements that idea for all four tables: SET STATISTICS IO ON ; WITH TestTable AS ( SELECT * FROM dbo.TestCHAR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id = ANY (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAX ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestTEXT ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAXOOR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; All four queries now return results in much less than a second, with memory grants between 6 and 12MB, and without spilling to tempdb. The small remaining inefficiency is in reading the id column values from the clustered primary key index. As a clustered index, it contains all the in-row data at its leaf. The CHAR and VARCHAR(MAX) tables store the padding column in-row, so id values are separated by a 3999-character column, plus row overhead. The TEXT and MAXOOR tables store the padding values off-row, so id values in the clustered index leaf are separated by the much-smaller off-row pointer structure. This difference is reflected in the number of logical page reads performed by the four queries: Table 'TestCHAR' logical reads 25511 lob logical reads 000 Table 'TestMAX'. logical reads 25511 lob logical reads 000 Table 'TestTEXT' logical reads 00412 lob logical reads 597 Table 'TestMAXOOR' logical reads 00413 lob logical reads 446 We can increase the density of the id values by creating a separate nonclustered index on the id column only. This is the same key as the clustered index, of course, but the nonclustered index will not include the rest of the in-row column data. CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestCHAR (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAX (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestTEXT (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAXOOR (id); The four queries can now use the very dense nonclustered index to quickly scan the id values, sort them by NEWID(), select the 150 ids we want, and then look up the padding data. The logical reads with the new indexes in place are: Table 'TestCHAR' logical reads 835 lob logical reads 0 Table 'TestMAX' logical reads 835 lob logical reads 0 Table 'TestTEXT' logical reads 686 lob logical reads 597 Table 'TestMAXOOR' logical reads 686 lob logical reads 448 With the new index, all four queries use the same query plan (click to enlarge): Performance Summary: 0.3 seconds elapsed time 6MB memory grant 0MB tempdb usage 1MB sort set 835 logical reads (CHAR, MAX) 686 logical reads (TEXT, MAXOOR) 597 LOB logical reads (TEXT) 448 LOB logical reads (MAXOOR) No sort warning I’ll leave it as an exercise for the reader to work out why trying to eliminate the Key Lookup by adding the padding column to the new nonclustered indexes would be a daft idea Conclusion This post is not about tuning queries that access columns containing big strings. It isn’t about the internal differences between TEXT and MAX data types either. It isn’t even about the cool use of UPDATE .WRITE used in the MAXOOR table load. No, this post is about something else: Many developers might not have tuned our starting example query at all – 5 seconds isn’t that bad, and the original query plan looks reasonable at first glance. Perhaps the NEWID() function would have been blamed for ‘just being slow’ – who knows. 5 seconds isn’t awful – unless your users expect sub-second responses – but using 250MB of memory and writing 200MB to tempdb certainly is! If ten sessions ran that query at the same time in production that’s 2.5GB of memory usage and 2GB hitting tempdb. Of course, not all queries can be rewritten to avoid large memory grants and sort spills using the key-lookup technique in this post, but that’s not the point either. The point of this post is that a basic understanding of execution plans is not enough. Tuning for logical reads and adding covering indexes is not enough. If you want to produce high-quality, scalable TSQL that won’t get you paged as soon as it hits production, you need a deep understanding of execution plans, and as much accurate, deep knowledge about SQL Server as you can lay your hands on. The advanced database developer has a wide range of tools to use in writing queries that perform well in a range of circumstances. By the way, the examples in this post were written for SQL Server 2008. They will run on 2005 and demonstrate the same principles, but you won’t get the same figures I did because 2005 had a rather nasty bug in the Top N Sort operator. Fair warning: if you do decide to run the scripts on a 2005 instance (particularly the parallel query) do it before you head out for lunch… This post is dedicated to the people of Christchurch, New Zealand. © 2011 Paul White email: @[email protected] twitter: @SQL_Kiwi

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Much Ado About Nothing: Stub Objects

- by user9154181

The Solaris 11 link-editor (ld) contains support for a new type of object that we call a stub object. A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be executed — the runtime linker will kill any process that attempts to load one. However, you can link to a stub object as a dependency, allowing the stub to act as a proxy for the real version of the object. You may well wonder if there is a point to producing an object that contains nothing but linking interface. As it turns out, stub objects are very useful for building large bodies of code such as Solaris. In the last year, we've had considerable success in applying them to one of our oldest and thorniest build problems. In this discussion, I will describe how we came to invent these objects, and how we apply them to building Solaris. This posting explains where the idea for stub objects came from, and details our long and twisty journey from hallway idea to standard link-editor feature. I expect that these details are mainly of interest to those who work on Solaris and its makefiles, those who have done so in the past, and those who work with other similar bodies of code. A subsequent posting will omit the history and background details, and instead discuss how to build and use stub objects. If you are mainly interested in what stub objects are, and don't care about the underlying software war stories, I encourage you to skip ahead. The Long Road To Stubs This all started for me with an email discussion in May of 2008, regarding a change request that was filed in 2002, entitled: 4631488 lib/Makefile is too patient: .WAITs should be reduced This CR encapsulates a number of cronic issues with Solaris builds: We build Solaris with a parallel make (dmake) that tries to build as much of the code base in parallel as possible. There is a lot of code to build, and we've long made use of parallelized builds to get the job done quicker. This is even more important in today's world of massively multicore hardware. Solaris contains a large number of executables and shared objects. Executables depend on shared objects, and shared objects can depend on each other. Before you can build an object, you need to ensure that the objects it needs have been built. This implies a need for serialization, which is in direct opposition to the desire to build everying in parallel. To accurately build objects in the right order requires an accurate set of make rules defining the things that depend on each other. This sounds simple, but the reality is quite complex. In practice, having programmers explicitly specify these dependencies is a losing strategy: It's really hard to get right. It's really easy to get it wrong and never know it because things build anyway. Even if you get it right, it won't stay that way, because dependencies between objects can change over time, and make cannot help you detect such drifing. You won't know that you got it wrong until the builds break. That can be a long time after the change that triggered the breakage happened, making it hard to connect the cause and the effect. Usually this happens just before a release, when the pressure is on, its hard to think calmly, and there is no time for deep fixes. As a poor compromise, the libraries in core Solaris were built using a set of grossly incomplete hand written rules, supplemented with a number of dmake .WAIT directives used to group the libraries into sets of non-interacting groups that can be built in parallel because we think they don't depend on each other. From time to time, someone will suggest that we could analyze the built objects themselves to determine their dependencies and then generate make rules based on those relationships. This is possible, but but there are complications that limit the usefulness of that approach: To analyze an object, you have to build it first. This is a classic chicken and egg scenario. You could analyze the results of a previous build, but then you're not necessarily going to get accurate rules for the current code. It should be possible to build the code without having a built workspace available. The analysis will take time, and remember that we're constantly trying to make builds faster, not slower. By definition, such an approach will always be approximate, and therefore only incremantally more accurate than the hand written rules described above. The hand written rules are fast and cheap, while this idea is slow and complex, so we stayed with the hand written approach. Solaris was built that way, essentially forever, because these are genuinely difficult problems that had no easy answer. The makefiles were full of build races in which the right outcomes happened reliably for years until a new machine or a change in build server workload upset the accidental balance of things. After figuring out what had happened, you'd mutter "How did that ever work?", add another incomplete and soon to be inaccurate make dependency rule to the system, and move on. This was not a satisfying solution, as we tend to be perfectionists in the Solaris group, but we didn't have a better answer. It worked well enough, approximately. And so it went for years. We needed a different approach — a new idea to cut the Gordian Knot. In that discussion from May 2008, my fellow linker-alien Rod Evans had the initial spark that lead us to a game changing series of realizations: The link-editor is used to link objects together, but it only uses the ELF metadata in the object, consisting of symbol tables, ELF versioning sections, and similar data. Notably, it does not look at, or understand, the machine code that makes an object useful at runtime. If you had an object that only contained the ELF metadata for a dependency, but not the code or data, the link-editor would find it equally useful for linking, and would never know the difference. Call it a stub object. In the core Solaris OS, we require all objects to be built with a link-editor mapfile that describes all of its publically available functions and data. Could we build a stub object using the mapfile for the real object? It ought to be very fast to build stub objects, as there are no input objects to process. Unlike the real object, stub objects would not actually require any dependencies, and so, all of the stubs for the entire system could be built in parallel. When building the real objects, one could link against the stub objects instead of the real dependencies. This means that all the real objects can be built built in parallel too, without any serialization. We could replace a system that requires perfect makefile rules with a system that requires no ordering rules whatsoever. The results would be considerably more robust. We immediately realized that this idea had potential, but also that there were many details to sort out, lots of work to do, and that perhaps it wouldn't really pan out. As is often the case, it would be necessary to do the work and see how it turned out. Following that conversation, I set about trying to build a stub object. We determined that a faithful stub has to do the following: Present the same set of global symbols, with the same ELF versioning, as the real object. Functions are simple — it suffices to have a symbol of the right type, possibly, but not necessarily, referencing a null function in its text segment. Copy relocations make data more complicated to stub. The possibility of a copy relocation means that when you create a stub, the data symbols must have the actual size of the real data. Any error in this will go uncaught at link time, and will cause tragic failures at runtime that are very hard to diagnose. For reasons too obscure to go into here, involving tentative symbols, it is also important that the data reside in bss, or not, matching its placement in the real object. If the real object has more than one symbol pointing at the same data item, we call these aliased symbols. All data symbols in the stub object must exhibit the same aliasing as the real object. We imagined the stub library feature working as follows: A command line option to ld tells it to produce a stub rather than a real object. In this mode, only mapfiles are examined, and any object or shared libraries on the command line are are ignored. The extra information needed (function or data, size, and bss details) would be added to the mapfile. When building the real object instead of the stub, the extra information for building stubs would be validated against the resulting object to ensure that they match. In exploring these ideas, I immediately run headfirst into the reality of the original mapfile syntax, a subject that I would later write about as The Problem(s) With Solaris SVR4 Link-Editor Mapfiles. The idea of extending that poor language was a non-starter. Until a better mapfile syntax became available, which seemed unlikely in 2008, the solution could not involve extentions to the mapfile syntax. Instead, we cooked up the idea (hack) of augmenting mapfiles with stylized comments that would carry the necessary information. A typical definition might look like: # DATA(i386) __iob 0x3c0 # DATA(amd64,sparcv9) __iob 0xa00 # DATA(sparc) __iob 0x140 iob; A further problem then became clear: If we can't extend the mapfile syntax, then there's no good way to extend ld with an option to produce stub objects, and to validate them against the real objects. The idea of having ld read comments in a mapfile and parse them for content is an unacceptable hack. The entire point of comments is that they are strictly for the human reader, and explicitly ignored by the tool. Taking all of these speed bumps into account, I made a new plan: A perl script reads the mapfiles, generates some small C glue code to produce empty functions and data definitions, compiles and links the stub object from the generated glue code, and then deletes the generated glue code. Another perl script used after both objects have been built, to compare the real and stub objects, using data from elfdump, and validate that they present the same linking interface. By June 2008, I had written the above, and generated a stub object for libc. It was a useful prototype process to go through, and it allowed me to explore the ideas at a deep level. Ultimately though, the result was unsatisfactory as a basis for real product. There were so many issues: The use of stylized comments were fine for a prototype, but not close to professional enough for shipping product. The idea of having to document and support it was a large concern. The ideal solution for stub objects really does involve having the link-editor accept the same arguments used to build the real object, augmented with a single extra command line option. Any other solution, such as our prototype script, will require makefiles to be modified in deeper ways to support building stubs, and so, will raise barriers to converting existing code. A validation script that rederives what the linker knew when it built an object will always be at a disadvantage relative to the actual linker that did the work. A stub object should be identifyable as such. In the prototype, there was no tag or other metadata that would let you know that they weren't real objects. Being able to identify a stub object in this way means that the file command can tell you what it is, and that the runtime linker can refuse to try and run a program that loads one. At that point, we needed to apply this prototype to building Solaris. As you might imagine, the task of modifying all the makefiles in the core Solaris code base in order to do this is a massive task, and not something you'd enter into lightly. The quality of the prototype just wasn't good enough to justify that sort of time commitment, so I tabled the project, putting it on my list of long term things to think about, and moved on to other work. It would sit there for a couple of years. Semi-coincidentally, one of the projects I tacked after that was to create a new mapfile syntax for the Solaris link-editor. We had wanted to do something about the old mapfile syntax for many years. Others before me had done some paper designs, and a great deal of thought had already gone into the features it should, and should not have, but for various reasons things had never moved beyond the idea stage. When I joined Sun in late 2005, I got involved in reviewing those things and thinking about the problem. Now in 2008, fresh from relearning for the Nth time why the old mapfile syntax was a huge impediment to linker progress, it seemed like the right time to tackle the mapfile issue. Paving the way for proper stub object support was not the driving force behind that effort, but I certainly had them in mind as I moved forward. The new mapfile syntax, which we call version 2, integrated into Nevada build snv_135 in in February 2010: 6916788 ld version 2 mapfile syntax PSARC/2009/688 Human readable and extensible ld mapfile syntax In order to prove that the new mapfile syntax was adequate for general purpose use, I had also done an overhaul of the ON consolidation to convert all mapfiles to use the new syntax, and put checks in place that would ensure that no use of the old syntax would creep back in. That work went back into snv_144 in June 2010: 6916796 OSnet mapfiles should use version 2 link-editor syntax That was a big putback, modifying 517 files, adding 18 new files, and removing 110 old ones. I would have done this putback anyway, as the work was already done, and the benefits of human readable syntax are obvious. However, among the justifications listed in CR 6916796 was this We anticipate adding additional features to the new mapfile language that will be applicable to ON, and which will require all sharable object mapfiles to use the new syntax. I never explained what those additional features were, and no one asked. It was premature to say so, but this was a reference to stub objects. By that point, I had already put together a working prototype link-editor with the necessary support for stub objects. I was pleased to find that building stubs was indeed very fast. On my desktop system (Ultra 24), an amd64 stub for libc can can be built in a fraction of a second: % ptime ld -64 -z stub -o stubs/libc.so.1 -G -hlibc.so.1 \ -ztext -zdefs -Bdirect ... real 0.019708910 user 0.010101680 sys 0.008528431 In order to go from prototype to integrated link-editor feature, I knew that I would need to prove that stub objects were valuable. And to do that, I knew that I'd have to switch the Solaris ON consolidation to use stub objects and evaluate the outcome. And in order to do that experiment, ON would first need to be converted to version 2 mapfiles. Sub-mission accomplished. Normally when you design a new feature, you can devise reasonably small tests to show it works, and then deploy it incrementally, letting it prove its value as it goes. The entire point of stub objects however was to demonstrate that they could be successfully applied to an extremely large and complex code base, and specifically to solve the Solaris build issues detailed above. There was no way to finesse the matter — in order to move ahead, I would have to successfully use stub objects to build the entire ON consolidation and demonstrate their value. In software, the need to boil the ocean can often be a warning sign that things are trending in the wrong direction. Conversely, sometimes progress demands that you build something large and new all at once. A big win, or a big loss — sometimes all you can do is try it and see what happens. And so, I spent some time staring at ON makefiles trying to get a handle on how things work, and how they'd have to change. It's a big and messy world, full of complex interactions, unspecified dependencies, special cases, and knowledge of arcane makefile features... ...and so, I backed away, put it down for a few months and did other work... ...until the fall, when I felt like it was time to stop thinking and pondering (some would say stalling) and get on with it. Without stubs, the following gives a simplified high level view of how Solaris is built: An initially empty directory known as the proto, and referenced via the ROOT makefile macro is established to receive the files that make up the Solaris distribution. A top level setup rule creates the proto area, and performs operations needed to initialize the workspace so that the main build operations can be launched, such as copying needed header files into the proto area. Parallel builds are launched to build the kernel (usr/src/uts), libraries (usr/src/lib), and commands. The install makefile target builds each item and delivers a copy to the proto area. All libraries and executables link against the objects previously installed in the proto, implying the need to synchronize the order in which things are built. Subsequent passes run lint, and do packaging. Given this structure, the additions to use stub objects are: A new second proto area is established, known as the stub proto and referenced via the STUBROOT makefile macro. The stub proto has the same structure as the real proto, but is used to hold stub objects. All files in the real proto are delivered as part of the Solaris product. In contrast, the stub proto is used to build the product, and then thrown away. A new target is added to library Makefiles called stub. This rule builds the stub objects. The ld command is designed so that you can build a stub object using the same ld command line you'd use to build the real object, with the addition of a single -z stub option. This means that the makefile rules for building the stub objects are very similar to those used to build the real objects, and many existing makefile definitions can be shared between them. A new target is added to the Makefiles called stubinstall which delivers the stub objects built by the stub rule into the stub proto. These rules reuse much of existing plumbing used by the existing install rule. The setup rule runs stubinstall over the entire lib subtree as part of its initialization. All libraries and executables link against the objects in the stub proto rather than the main proto, and can therefore be built in parallel without any synchronization. There was no small way to try this that would yield meaningful results. I would have to take a leap of faith and edit approximately 1850 makefiles and 300 mapfiles first, trusting that it would all work out. Once the editing was done, I'd type make and see what happened. This took about 6 weeks to do, and there were many dark days when I'd question the entire project, or struggle to understand some of the many twisted and complex situations I'd uncover in the makefiles. I even found a couple of new issues that required changes to the new stub object related code I'd added to ld. With a substantial amount of encouragement and help from some key people in the Solaris group, I eventually got the editing done and stub objects for the entire workspace built. I found that my desktop system could build all the stub objects in the workspace in roughly a minute. This was great news, as it meant that use of the feature is effectively free — no one was likely to notice or care about the cost of building them. After another week of typing make, fixing whatever failed, and doing it again, I succeeded in getting a complete build! The next step was to remove all of the make rules and .WAIT statements dedicated to controlling the order in which libraries under usr/src/lib are built. This came together pretty quickly, and after a few more speed bumps, I had a workspace that built cleanly and looked like something you might actually be able to integrate someday. This was a significant milestone, but there was still much left to do. I turned to doing full nightly builds. Every type of build (open, closed, OpenSolaris, export, domestic) had to be tried. Each type failed in a new and unique way, requiring some thinking and rework. As things came together, I became aware of things that could have been done better, simpler, or cleaner, and those things also required some rethinking, the seeking of wisdom from others, and some rework. After another couple of weeks, it was in close to final form. My focus turned towards the end game and integration. This was a huge workspace, and needed to go back soon, before changes in the gate would made merging increasingly difficult. At this point, I knew that the stub objects had greatly simplified the makefile logic and uncovered a number of race conditions, some of which had been there for years. I assumed that the builds were faster too, so I did some builds intended to quantify the speedup in build time that resulted from this approach. It had never occurred to me that there might not be one. And so, I was very surprised to find that the wall clock build times for a stock ON workspace were essentially identical to the times for my stub library enabled version! This is why it is important to always measure, and not just to assume. One can tell from first principles, based on all those removed dependency rules in the library makefile, that the stub object version of ON gives dmake considerably more opportunities to overlap library construction. Some hypothesis were proposed, and shot down: Could we have disabled dmakes parallel feature? No, a quick check showed things being build in parallel. It was suggested that we might be I/O bound, and so, the threads would be mostly idle. That's a plausible explanation, but system stats didn't really support it. Plus, the timing between the stub and non-stub cases were just too suspiciously identical. Are our machines already handling as much parallelism as they are capable of, and unable to exploit these additional opportunities? Once again, we didn't see the evidence to back this up. Eventually, a more plausible and obvious reason emerged: We build the libraries and commands (usr/src/lib, usr/src/cmd) in parallel with the kernel (usr/src/uts). The kernel is the long leg in that race, and so, wall clock measurements of build time are essentially showing how long it takes to build uts. Although it would have been nice to post a huge speedup immediately, we can take solace in knowing that stub objects simplify the makefiles and reduce the possibility of race conditions. The next step in reducing build time should be to find ways to reduce or overlap the uts part of the builds. When that leg of the build becomes shorter, then the increased parallelism in the libs and commands will pay additional dividends. Until then, we'll just have to settle for simpler and more robust. And so, I integrated the link-editor support for creating stub objects into snv_153 (November 2010) with 6993877 ld should produce stub objects PSARC/2010/397 ELF Stub Objects followed by the work to convert the ON consolidation in snv_161 (February 2011) with 7009826 OSnet should use stub objects 4631488 lib/Makefile is too patient: .WAITs should be reduced This was a huge putback, with 2108 modified files, 8 new files, and 2 removed files. Due to the size, I was allowed a window after snv_160 closed in which to do the putback. It went pretty smoothly for something this big, a few more preexisting race conditions would be discovered and addressed over the next few weeks, and things have been quiet since then. Conclusions and Looking Forward Solaris has been built with stub objects since February. The fact that developers no longer specify the order in which libraries are built has been a big success, and we've eliminated an entire class of build error. That's not to say that there are no build races left in the ON makefiles, but we've taken a substantial bite out of the problem while generally simplifying and improving things. The introduction of a stub proto area has also opened some interesting new possibilities for other build improvements. As this article has become quite long, and as those uses do not involve stub objects, I will defer that discussion to a future article.

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Using the ASP.NET Cache to cache data in a Model or Business Object layer, without a dependency on System.Web in the layer - Part One.

- by Rhames

ASP.NET applications can make use of the System.Web.Caching.Cache object to cache data and prevent repeated expensive calls to a database or other store. However, ideally an application should make use of caching at the point where data is retrieved from the database, which typically is inside a Business Objects or Model layer. One of the key features of using a UI pattern such as Model-View-Presenter (MVP) or Model-View-Controller (MVC) is that the Model and Presenter (or Controller) layers are developed without any knowledge of the UI layer. Introducing a dependency on System.Web into the Model layer would break this independence of the Model from the View. This article gives a solution to this problem, using dependency injection to inject the caching implementation into the Model layer at runtime. This allows caching to be used within the Model layer, without any knowledge of the actual caching mechanism that will be used. Create a sample application to use the caching solution Create a test SQL Server database This solution uses a SQL Server database with the same Sales data used in my previous post on calculating running totals. The advantage of using this data is that it gives nice slow queries that will exaggerate the effect of using caching! To create the data, first create a new SQL database called CacheSample. Next run the following script to create the Sale table and populate it: USE CacheSample GO CREATE TABLE Sale(DayCount smallint, Sales money) CREATE CLUSTERED INDEX ndx_DayCount ON Sale(DayCount) go INSERT Sale VALUES (1,120) INSERT Sale VALUES (2,60) INSERT Sale VALUES (3,125) INSERT Sale VALUES (4,40) DECLARE @DayCount smallint, @Sales money SET @DayCount = 5 SET @Sales = 10 WHILE @DayCount < 5000 BEGIN INSERT Sale VALUES (@DayCount,@Sales) SET @DayCount = @DayCount + 1 SET @Sales = @Sales + 15 END Next create a stored procedure to calculate the running total, and return a specified number of rows from the Sale table, using the following script: USE [CacheSample] GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: Robin -- Create date: -- Description: -- ============================================= CREATE PROCEDURE [dbo].[spGetRunningTotals] -- Add the parameters for the stored procedure here @HighestDayCount smallint = null AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; IF @HighestDayCount IS NULL SELECT @HighestDayCount = MAX(DayCount) FROM dbo.Sale DECLARE @SaleTbl TABLE (DayCount smallint, Sales money, RunningTotal money) DECLARE @DayCount smallint, @Sales money, @RunningTotal money SET @RunningTotal = 0 SET @DayCount = 0 DECLARE rt_cursor CURSOR FOR SELECT DayCount, Sales FROM Sale ORDER BY DayCount OPEN rt_cursor FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales WHILE @@FETCH_STATUS = 0 AND @DayCount <= @HighestDayCount BEGIN SET @RunningTotal = @RunningTotal + @Sales INSERT @SaleTbl VALUES (@DayCount,@Sales,@RunningTotal) FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales END CLOSE rt_cursor DEALLOCATE rt_cursor SELECT DayCount, Sales, RunningTotal FROM @SaleTbl END GO Create the Sample ASP.NET application In Visual Studio create a new solution and add a class library project called CacheSample.BusinessObjects and an ASP.NET web application called CacheSample.UI. The CacheSample.BusinessObjects project will contain a single class to represent a Sale data item, with all the code to retrieve the sales from the database included in it for simplicity (normally I would at least have a separate Repository or other object that is responsible for retrieving data, and probably a data access layer as well, but for this sample I want to keep it simple). The C# code for the Sale class is shown below: using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; namespace CacheSample.BusinessObjects { public class Sale { public Int16 DayCount { get; set; } public decimal Sales { get; set; } public decimal RunningTotal { get; set; } public static IEnumerable<Sale> GetSales(int? highestDayCount) { List<Sale> sales = new List<Sale>(); SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt); if (highestDayCount.HasValue) highestDayCountParameter.Value = highestDayCount; else highestDayCountParameter.Value = DBNull.Value; string connectionStr = System.Configuration.ConfigurationManager .ConnectionStrings["CacheSample"].ConnectionString; using(SqlConnection sqlConn = new SqlConnection(connectionStr)) using (SqlCommand sqlCmd = sqlConn.CreateCommand()) { sqlCmd.CommandText = "spGetRunningTotals"; sqlCmd.CommandType = CommandType.StoredProcedure; sqlCmd.Parameters.Add(highestDayCountParameter); sqlConn.Open(); using (SqlDataReader dr = sqlCmd.ExecuteReader()) { while (dr.Read()) { Sale newSale = new Sale(); newSale.DayCount = dr.GetInt16(0); newSale.Sales = dr.GetDecimal(1); newSale.RunningTotal = dr.GetDecimal(2); sales.Add(newSale); } } } return sales; } } } The static GetSale() method makes a call to the spGetRunningTotals stored procedure and then reads each row from the returned SqlDataReader into an instance of the Sale class, it then returns a List of the Sale objects, as IEnnumerable<Sale>. A reference to System.Configuration needs to be added to the CacheSample.BusinessObjects project so that the connection string can be read from the web.config file. In the CacheSample.UI ASP.NET project, create a single web page called ShowSales.aspx, and make this the default start up page. This page will contain a single button to call the GetSales() method and a label to display the results. The html mark up and the C# code behind are shown below: ShowSales.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ShowSales.aspx.cs" Inherits="CacheSample.UI.ShowSales" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Cache Sample - Show All Sales</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Button ID="btnTest1" runat="server" onclick="btnTest1_Click" Text="Get All Sales" />     <asp:Label ID="lblResults" runat="server"></asp:Label> </div> </form> </body> </html> ShowSales.aspx.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using CacheSample.BusinessObjects; namespace CacheSample.UI { public partial class ShowSales : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void btnTest1_Click(object sender, EventArgs e) { System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch(); stopWatch.Start(); var sales = Sale.GetSales(null); var lastSales = sales.Last(); stopWatch.Stop(); lblResults.Text = string.Format( "Count of Sales: {0}, Last DayCount: {1}, Total Sales: {2}. Query took {3} ms", sales.Count(), lastSales.DayCount, lastSales.RunningTotal, stopWatch.ElapsedMilliseconds); } } } Finally we need to add a connection string to the CacheSample SQL Server database, called CacheSample, to the web.config file: <?xmlversion="1.0"?> <configuration> <connectionStrings> <addname="CacheSample" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample" providerName="System.Data.SqlClient" /> </connectionStrings> <system.web> <compilationdebug="true"targetFramework="4.0" /> </system.web> </configuration> Run the application and click the button a few times to see how long each call to the database takes. On my system, each query takes about 450ms. Next I shall look at a solution to use the ASP.NET caching to cache the data returned by the query, so that subsequent requests to the GetSales() method are much faster. Adding Data Caching Support I am going to create my caching support in a separate project called CacheSample.Caching, so the next step is to add a class library to the solution. We shall be using the application configuration to define the implementation of our caching system, so we need a reference to System.Configuration adding to the project. ICacheProvider<T> Interface The first step in adding caching to our application is to define an interface, called ICacheProvider, in the CacheSample.Caching project, with methods to retrieve any data from the cache or to retrieve the data from the data source if it is not present in the cache. Dependency Injection will then be used to inject an implementation of this interface at runtime, allowing the users of the interface (i.e. the CacheSample.BusinessObjects project) to be completely unaware of how the caching is actually implemented. As data of any type maybe retrieved from the data source, it makes sense to use generics in the interface, with a generic type parameter defining the data type associated with a particular instance of the cache interface implementation. The C# code for the ICacheProvider interface is shown below: using System; using System.Collections.Generic; namespace CacheSample.Caching { public interface ICacheProvider { } public interface ICacheProvider<T> : ICacheProvider { T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); } } The empty non-generic interface will be used as a type in a Dictionary generic collection later to store instances of the ICacheProvider<T> implementation for reuse, I prefer to use a base interface when doing this, as I think the alternative of using object makes for less clear code. The ICacheProvider<T> interface defines two overloaded Fetch methods, the difference between these is that one will return a single instance of the type T and the other will return an IEnumerable<T>, providing support for easy caching of collections of data items. Both methods will take a key parameter, which will uniquely identify the cached data, a delegate of type Func<T> or Func<IEnumerable<T>> which will provide the code to retrieve the data from the store if it is not present in the cache, and absolute or relative expiry policies to define when a cached item should expire. Note that at present there is no support for cache dependencies, but I shall be showing a method of adding this in part two of this article. CacheProviderFactory Class We need a mechanism of creating instances of our ICacheProvider<T> interface, using Dependency Injection to get the implementation of the interface. To do this we shall create a CacheProviderFactory static class in the CacheSample.Caching project. This factory will provide a generic static method called GetCacheProvider<T>(), which shall return instances of ICacheProvider<T>. We can then call this factory method with the relevant data type (for example the Sale class in the CacheSample.BusinessObject project) to get a instance of ICacheProvider for that type (e.g. call CacheProviderFactory.GetCacheProvider<Sale>() to get the ICacheProvider<Sale> implementation). The C# code for the CacheProviderFactory is shown below: using System; using System.Collections.Generic; using CacheSample.Caching.Configuration; namespace CacheSample.Caching { public static class CacheProviderFactory { private static Dictionary<Type, ICacheProvider> cacheProviders = new Dictionary<Type, ICacheProvider>(); private static object syncRoot = new object(); ///<summary> /// Factory method to create or retrieve an implementation of the /// ICacheProvider interface for type <typeparamref name="T"/>. ///</summary> ///<typeparam name="T"> /// The type that this cache provider instance will work with ///</typeparam> ///<returns>An instance of the implementation of ICacheProvider for type ///<typeparamref name="T"/>, as specified by the application /// configuration</returns> public static ICacheProvider<T> GetCacheProvider<T>() { ICacheProvider<T> cacheProvider = null; // Get the Type reference for the type parameter T Type typeOfT = typeof(T); // Lock the access to the cacheProviders dictionary // so multiple threads can work with it lock (syncRoot) { // First check if an instance of the ICacheProvider implementation // already exists in the cacheProviders dictionary for the type T if (cacheProviders.ContainsKey(typeOfT)) cacheProvider = (ICacheProvider<T>)cacheProviders[typeOfT]; else { // There is not already an instance of the ICacheProvider in // cacheProviders for the type T // so we need to create one // Get the Type reference for the application's implementation of // ICacheProvider from the configuration Type cacheProviderType = Type.GetType(CacheProviderConfigurationSection.Current. CacheProviderType); if (cacheProviderType != null) { // Now get a Type reference for the Cache Provider with the // type T generic parameter Type typeOfCacheProviderTypeForT = cacheProviderType.MakeGenericType(new Type[] { typeOfT }); if (typeOfCacheProviderTypeForT != null) { // Create the instance of the Cache Provider and add it to // the cacheProviders dictionary for future use cacheProvider = (ICacheProvider<T>)Activator. CreateInstance(typeOfCacheProviderTypeForT); cacheProviders.Add(typeOfT, cacheProvider); } } } } return cacheProvider; } } } As this code uses Activator.CreateInstance() to create instances of the ICacheProvider<T> implementation, which is a slow process, the factory class maintains a Dictionary of the previously created instances so that a cache provider needs to be created only once for each type. The type of the implementation of ICacheProvider<T> is read from a custom configuration section in the application configuration file, via the CacheProviderConfigurationSection class, which is described below. CacheProviderConfigurationSection Class The implementation of ICacheProvider<T> will be specified in a custom configuration section in the application’s configuration. To handle this create a folder in the CacheSample.Caching project called Configuration, and add a class called CacheProviderConfigurationSection to this folder. This class will extend the System.Configuration.ConfigurationSection class, and will contain a single string property called CacheProviderType. The C# code for this class is shown below: using System; using System.Configuration; namespace CacheSample.Caching.Configuration { internal class CacheProviderConfigurationSection : ConfigurationSection { public static CacheProviderConfigurationSection Current { get { return (CacheProviderConfigurationSection) ConfigurationManager.GetSection("cacheProvider"); } } [ConfigurationProperty("type", IsRequired=true)] public string CacheProviderType { get { return (string)this["type"]; } } } } Adding Data Caching to the Sales Class We now have enough code in place to add caching to the GetSales() method in the CacheSample.BusinessObjects.Sale class, even though we do not yet have an implementation of the ICacheProvider<T> interface. We need to add a reference to the CacheSample.Caching project to CacheSample.BusinessObjects so that we can use the ICacheProvider<T> interface within the GetSales() method. Once the reference is added, we can first create a unique string key based on the method name and the parameter value, so that the same cache key is used for repeated calls to the method with the same parameter values. Then we get an instance of the cache provider for the Sales type, using the CacheProviderFactory, and pass the existing code to retrieve the data from the database as the retrievalMethod delegate in a call to the Cache Provider Fetch() method. The C# code for the modified GetSales() method is shown below: public static IEnumerable<Sale> GetSales(int? highestDayCount) { string cacheKey = string.Format("CacheSample.BusinessObjects.GetSalesWithCache({0})", highestDayCount); return CacheSample.Caching.CacheProviderFactory. GetCacheProvider<Sale>().Fetch(cacheKey, delegate() { List<Sale> sales = new List<Sale>(); SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt); if (highestDayCount.HasValue) highestDayCountParameter.Value = highestDayCount; else highestDayCountParameter.Value = DBNull.Value; string connectionStr = System.Configuration.ConfigurationManager. ConnectionStrings["CacheSample"].ConnectionString; using (SqlConnection sqlConn = new SqlConnection(connectionStr)) using (SqlCommand sqlCmd = sqlConn.CreateCommand()) { sqlCmd.CommandText = "spGetRunningTotals"; sqlCmd.CommandType = CommandType.StoredProcedure; sqlCmd.Parameters.Add(highestDayCountParameter); sqlConn.Open(); using (SqlDataReader dr = sqlCmd.ExecuteReader()) { while (dr.Read()) { Sale newSale = new Sale(); newSale.DayCount = dr.GetInt16(0); newSale.Sales = dr.GetDecimal(1); newSale.RunningTotal = dr.GetDecimal(2); sales.Add(newSale); } } } return sales; }, null, new TimeSpan(0, 10, 0)); } This example passes the code to retrieve the Sales data from the database to the Cache Provider as an anonymous method, however it could also be written as a lambda. The main advantage of using an anonymous function (method or lambda) is that the code inside the anonymous function can access the parameters passed to the GetSales() method. Finally the absolute expiry is set to null, and the relative expiry set to 10 minutes, to indicate that the cache entry should be removed 10 minutes after the last request for the data. As the ICacheProvider<T> has a Fetch() method that returns IEnumerable<T>, we can simply return the results of the Fetch() method to the caller of the GetSales() method. This should be all that is needed for the GetSales() method to now retrieve data from a cache after the first time the data has be retrieved from the database. Implementing a ASP.NET Cache Provider The final step is to actually implement the ICacheProvider<T> interface, and add the implementation details to the web.config file for the dependency injection. The cache provider implementation needs to have access to System.Web. Therefore it could be placed in the CacheSample.UI project, or in its own project that has a reference to System.Web. Implementing the Cache Provider in a separate project is my favoured approach. Create a new project inside the solution called CacheSample.CacheProvider, and add references to System.Web and CacheSample.Caching to this project. Add a class to the project called AspNetCacheProvider. Make the class a generic class by adding the generic parameter <T> and indicate that the class implements ICacheProvider<T>. The C# code for the AspNetCacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching; using CacheSample.Caching; namespace CacheSample.CacheProvider { public class AspNetCacheProvider<T> : ICacheProvider<T> { #region ICacheProvider<T> Members public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry); } public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry); } #endregion #region Helper Methods private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { U value; if (!TryGetValue<U>(key, out value)) { value = retrieveData(); if (!absoluteExpiry.HasValue) absoluteExpiry = Cache.NoAbsoluteExpiration; if (!relativeExpiry.HasValue) relativeExpiry = Cache.NoSlidingExpiration; HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value); } return value; } private bool TryGetValue<U>(string key, out U value) { object cachedValue = HttpContext.Current.Cache.Get(key); if (cachedValue == null) { value = default(U); return false; } else { try { value = (U)cachedValue; return true; } catch { value = default(U); return false; } } } #endregion } } The two interface Fetch() methods call a private method called FetchAndCache(). This method first checks for a element in the HttpContext.Current.Cache with the specified cache key, and if so tries to cast this to the specified type (either T or IEnumerable<T>). If the cached element is found, the FetchAndCache() method simply returns it. If it is not found in the cache, the method calls the retrievalMethod delegate to get the data from the data source, and then adds this to the HttpContext.Current.Cache. The final step is to add the AspNetCacheProvider class to the relevant custom configuration section in the CacheSample.UI.Web.Config file. To do this there needs to be a <configSections> element added as the first element in <configuration>. This will match a custom section called <cacheProvider> with the CacheProviderConfigurationSection. Then we add a <cacheProvider> element, with a type property set to the fully qualified assembly name of the AspNetCacheProvider class, as shown below: <?xmlversion="1.0"?> <configuration> <configSections> <sectionname="cacheProvider" type="CacheSample.Base.Configuration.CacheProviderConfigurationSection, CacheSample.Base" /> </configSections> <connectionStrings> <addname="CacheSample" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample" providerName="System.Data.SqlClient" /> </connectionStrings> <cacheProvidertype="CacheSample.CacheProvider.AspNetCacheProvider`1, CacheSample.CacheProvider, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"> </cacheProvider> <system.web> <compilationdebug="true"targetFramework="4.0" /> </system.web> </configuration> One point to note is that the fully qualified assembly name of the AspNetCacheProvider class includes the notation `1 after the class name, which indicates that it is a generic class with a single generic type parameter. The CacheSample.UI project needs to have references added to CacheSample.Caching and CacheSample.CacheProvider so that the actual application is aware of the relevant cache provider implementation. Conclusion After implementing this solution, you should have a working cache provider mechanism, that will allow the middle and data access layers to implement caching support when retrieving data, without any knowledge of the actually caching implementation. If the UI is not ASP.NET based, if for example it is Winforms or WPF, the implementation of ICacheProvider<T> would be written around whatever technology is available. It could even be a standalone caching system that takes full responsibility for adding and removing items from a global store. The next part of this article will show how this caching mechanism may be extended to provide support for cache dependencies, such as the System.Web.Caching.SqlCacheDependency. Another possible extension would be to cache the cache provider implementations instead of storing them in a static Dictionary in the CacheProviderFactory. This would prevent a build up of seldom used cache providers in the application memory, as they could be removed from the cache if not used often enough, although in reality there are probably unlikely to be vast numbers of cache provider implementation instances, as most applications do not have a massive number of business object or model types.

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Partner Blog Series: PwC Perspectives - The Gotchas, The Do's and Don'ts for IDM Implementations

- by Tanu Sood

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mso-tstyle-border-bottom-themecolor:accent6; font-family:"Arial Narrow","sans-serif"; mso-ascii-font-family:Georgia; mso-ascii-theme-font:major-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:major-fareast; mso-hansi-font-family:Georgia; mso-hansi-theme-font:major-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:major-bidi;} table.MsoTableMediumList1Accent6LastRow {mso-style-name:"Medium List 1 - Accent 6"; mso-table-condition:last-row; mso-style-priority:65; mso-style-unhide:no; mso-tstyle-border-top:1.0pt solid #E0301E; mso-tstyle-border-top-themecolor:accent6; mso-tstyle-border-bottom:1.0pt solid #E0301E; mso-tstyle-border-bottom-themecolor:accent6; color:#968C6D; mso-themecolor:text2; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableMediumList1Accent6FirstCol {mso-style-name:"Medium List 1 - Accent 6"; mso-table-condition:first-column; mso-style-priority:65; mso-style-unhide:no; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableMediumList1Accent6LastCol {mso-style-name:"Medium List 1 - Accent 6"; mso-table-condition:last-column; mso-style-priority:65; mso-style-unhide:no; mso-tstyle-border-top:1.0pt solid #E0301E; mso-tstyle-border-top-themecolor:accent6; mso-tstyle-border-bottom:1.0pt solid #E0301E; mso-tstyle-border-bottom-themecolor:accent6; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableMediumList1Accent6OddColumn {mso-style-name:"Medium List 1 - Accent 6"; mso-table-condition:odd-column; mso-style-priority:65; mso-style-unhide:no; mso-tstyle-shading:#F7CBC7; mso-tstyle-shading-themecolor:accent6; mso-tstyle-shading-themetint:63;} table.MsoTableMediumList1Accent6OddRow {mso-style-name:"Medium List 1 - Accent 6"; mso-table-condition:odd-row; mso-style-priority:65; mso-style-unhide:no; mso-tstyle-shading:#F7CBC7; mso-tstyle-shading-themecolor:accent6; mso-tstyle-shading-themetint:63;} It is generally accepted among business communities that technology by itself is not a silver bullet to all problems, but when it is combined with leading practices, strategy, careful planning and execution, it can create a recipe for success. This post attempts to highlight some of the best practices along with dos & don’ts that our practice has accumulated over the years in the identity & access management space in general, and also in the context of R2, in particular. Best Practices The following section illustrates the leading practices in “How” to plan, implement and sustain a successful OIM deployment, based on our collective experience. Planning is critical, but often overlooked A common approach to planning an IAM program that we identify with our clients is the three step process involving a current state assessment, a future state roadmap and an executable strategy to get there. It is extremely beneficial for clients to assess their current IAM state, perform gap analysis, document the recommended controls to address the gaps, align future state roadmap to business initiatives and get buy in from all stakeholders involved to improve the chances of success. When designing an enterprise-wide solution, the scalability of the technology must accommodate the future growth of the enterprise and the projected identity transactions over several years. Aligning the implementation schedule of OIM to related information technology projects increases the chances of success. As a baseline, it is recommended to match hardware specifications to the sizing guide for R2 published by Oracle. Adherence to this will help ensure that the hardware used to support OIM will not become a bottleneck as the adoption of new services increases. If your Organization has numerous connected applications that rely on reconciliation to synchronize the access data into OIM, consider hosting dedicated instances to handle reconciliation. Finally, ensure the use of clustered environment for development and have at least three total environments to help facilitate a controlled migration to production. If your Organization is planning to implement role based access control, we recommend performing a role mining exercise and consolidate your enterprise roles to keep them manageable. In addition, many Organizations have multiple approval flows to control access to critical roles, applications and entitlements. If your Organization falls into this category, we highly recommend that you limit the number of approval workflows to a small set. Most Organizations have operations managed across data centers with backend database synchronization, if your Organization falls into this category, ensure that the overall latency between the datacenters when replicating the databases is less than ten milliseconds to ensure that there are no front office performance impacts. Ingredients for a successful implementation During the development phase of your project, there are a number of guidelines that can be followed to help increase the chances for success. Most implementations cannot be completed without the use of customizations. If your implementation requires this, it’s a good practice to perform code reviews to help ensure quality and reduce code bottlenecks related to performance. We have observed at our clients that the development process works best when team members adhere to coding leading practices. Plan for time to correct coding defects and ensure developers are empowered to report their own bugs for maximum transparency. Many organizations struggle with defining a consistent approach to managing logs. This is particularly important due to the amount of information that can be logged by OIM. We recommend Oracle Diagnostics Logging (ODL) as an alternative to be used for logging. ODL allows log files to be formatted in XML for easy parsing and does not require a server restart when the log levels are changed during troubleshooting. Testing is a vital part of any large project, and an OIM R2 implementation is no exception. We suggest that at least one lower environment should use production-like data and connectors. Configurations should match as closely as possible. For example, use secure channels between OIM and target platforms in pre-production environments to test the configurations, the migration processes of certificates, and the additional overhead that encryption could impose. Finally, we ask our clients to perform database backups regularly and before any major change event, such as a patch or migration between environments. In the lowest environments, we recommend to have at least a weekly backup in order to prevent significant loss of time and effort. Similarly, if your organization is using virtual machines for one or more of the environments, it is recommended to take frequent snapshots so that rollbacks can occur in the event of improper configuration. Operate & sustain the solution to derive maximum benefits When migrating OIM R2 to production, it is important to perform certain activities that will help achieve a smoother transition. At our clients, we have seen that splitting the OIM tables into their own tablespaces by categories (physical tables, indexes, etc.) can help manage database growth effectively. If we notice that a client hasn’t enabled the Oracle-recommended indexing in the applicable database, we strongly suggest doing so to improve performance. Additionally, we work with our clients to make sure that the audit level is set to fit the organization’s auditing needs and sometimes even allocate UPA tables and indexes into their own table-space for better maintenance. Finally, many of our clients have set up schedules for reconciliation tables to be archived at regular intervals in order to keep the size of the database(s) reasonable and result in optimal database performance. For our clients that anticipate availability issues with target applications, we strongly encourage the use of the offline provisioning capabilities of OIM R2. This reduces the provisioning process for a given target application dependency on target availability and help avoid broken workflows. To account for this and other abnormalities, we also advocate that OIM’s monitoring controls be configured to alert administrators on any abnormal situations. Within OIM R2, we have begun advising our clients to utilize the ‘profile’ feature to encapsulate multiple commonly requested accounts, roles, and/or entitlements into a single item. By setting up a number of profiles that can be searched for and used, users will spend less time performing the same exact steps for common tasks. We advise our clients to follow the Oracle recommended guides for database and application server tuning which provides a good baseline configuration. It offers guidance on database connection pools, connection timeouts, user interface threads and proper handling of adapters/plug-ins. All of these can be important configurations that will allow faster provisioning and web page response times. Many of our clients have begun to recognize the value of data mining and a remediation process during the initial phases of an implementation (to help ensure high quality data gets loaded) and beyond (to support ongoing maintenance and business-as-usual processes). A successful program always begins with identifying the data elements and assigning a classification level based on criticality, risk, and availability. It should finish by following through with a remediation process. Dos & Don’ts Here are the most common dos and don'ts that we socialize with our clients, derived from our experience implementing the solution. Dos Don’ts Scope the project into phases with realistic goals. Look for quick wins to show success and value to the stake holders. Avoid “boiling the ocean” and trying to integrate all enterprise applications in the first phase. Establish an enterprise ID (universal unique ID across the enterprise) earlier in the program. Avoid major UI customizations that require code changes. Have a plan in place to patch during the project, which helps alleviate any major issues or roadblocks (product and database). Avoid publishing all the target entitlements if you don't anticipate their usage during access request. Assess your current state and prepare a roadmap to address your operations, tactical and strategic goals, align it with your business priorities. Avoid integrating non-production environments with your production target systems. Defer complex integrations to the later phases and take advantage of lessons learned from previous phases Avoid creating multiple accounts for the same user on the same system, if there is an opportunity to do so. Have an identity and access data quality initiative built into your plan to identify and remediate data related issues early on. Avoid creating complex approval workflows that would negative impact productivity and SLAs. Identify the owner of the identity systems with fair IdM knowledge and empower them with authority to make product related decisions. This will help ensure overcome any design hurdles. Avoid creating complex designs that are not sustainable long term and would need major overhaul during upgrades. Shadow your internal or external consulting resources during the implementation to build the necessary product skills needed to operate and sustain the solution. Avoid treating IAM as a point solution and have appropriate level of communication and training plan for the IT and business users alike. Conclusion In our experience, Identity programs will struggle with scope, proper resourcing, and more. We suggest that companies consider the suggestions discussed in this post and leverage them to help enable their identity and access program. This concludes PwC blog series on R2 for the month and we sincerely hope that the information we have shared thus far has been beneficial. For more information or if you have questions, you can reach out to Rex Thexton, Senior Managing Director, PwC and or Dharma Padala, Director, PwC. We look forward to hearing from you. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:12.0pt; mso-para-margin-left:0in; line-height:12.0pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Arial","sans-serif"; mso-ascii-font-family:Arial; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Arial; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Meet the Writers: Dharma Padala is a Director in the Advisory Security practice within PwC. He has been implementing medium to large scale Identity Management solutions across multiple industries including utility, health care, entertainment, retail and financial sectors. Dharma has 14 years of experience in delivering IT solutions out of which he has been implementing Identity Management solutions for the past 8 years. Praveen Krishna is a Manager in the Advisory Security practice within PwC. Over the last decade Praveen has helped clients plan, architect and implement Oracle identity solutions across diverse industries. His experience includes delivering security across diverse topics like network, infrastructure, application and data where he brings a holistic point of view to problem solving. Scott MacDonald is a Director in the Advisory Security practice within PwC. He has consulted for several clients across multiple industries including financial services, health care, automotive and retail. Scott has 10 years of experience in delivering Identity Management solutions. John Misczak is a member of the Advisory Security practice within PwC. He has experience implementing multiple Identity and Access Management solutions, specializing in Oracle Identity Manager and Business Process Engineering Language (BPEL).

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