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  • mysql thread count

    - by Ryan M.
    We have a web application that uses apache and mysql. Generally (according to Munin) our MySQL thread count sits between 2 and 4 at all times. The other day, our server almost came to a halt. HTTP requests were slow or wouldn't go through at all, SSH would work, but would take 30+ seconds to register keystrokes, etc.. So we pull up Munin and the only thing that's out of normal boundaries is the Mysql thread count. CPU usage was under 1%, load was under 1.0, plenty of available RAM. As mentioned before, the thread count floats around 2 to 4. At the time of our slow downs it had spiked to 14. So I start poking around the Internet and I see that in most cases, you'll start to see a higher thread count when you start running into slow queries. If I understand it correctly, the request comes in that takes a while to process, in the mean time other requests are coming in, so a new thread will be created to work on the request (yes?). But at the time of the slow down, we had 0 slow queries. My question is: What else can cause mysql to create additional threads. And would this sudden spike in threads possibly cause the server to slow down? To fix the issue, we restarted apache and everything went back to it's beautiful, normal self. Considering the the Server Vitals (CPU, RAM, Network, etc) were all ideal, and the thread count was the only thing out of place, this seems like the most logical thing to pursue as the possible cause. If it matters, we're on Mysql 5.1.40. Server is FreeBSD 7.2 and the server in question is inside a jail.

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  • java.lang.NoSuchMethodError: main Exception in thread "main" .

    - by russell
    I Cant understand why this messege come--------- java.lang.NoSuchMethodError: main Exception in thread "main" . I know it expecting main() method but as i m building an applet which does not contain main method rather contain init() method.So what will i do??My code is s follow --- import java.applet.*; import java.awt.*; public class Ballbewegung1 extends Applet implements Runnable { // Initialisierung der Variablen int x_pos = 10; // x - Position des Balles int y_pos = 100; // y - Position des Balles int radius = 20; // Radius des Balles public void init() { setBackground (Color.blue); } public void start () { // Schaffen eines neuen Threads, in dem das Spiel l?uft Thread th = new Thread (this); // Starten des Threads th.start (); } public void stop() { } public void destroy() { } public void run () { // Erniedrigen der ThreadPriority um zeichnen zu erleichtern Thread.currentThread().setPriority(Thread.MIN_PRIORITY); // Solange true ist l?uft der Thread weiter while (true) { // Ver?ndern der x- Koordinate x_pos ++; // Neuzeichnen des Applets repaint(); try { // Stoppen des Threads f?r in Klammern angegebene Millisekunden Thread.sleep (20); } catch (InterruptedException ex) { // do nothing } // Zur?cksetzen der ThreadPriority auf Maximalwert Thread.currentThread().setPriority(Thread.MAX_PRIORITY); } } public void paint (Graphics g) { g.setColor (Color.red); g.fillOval (x_pos - radius, y_pos - radius, 2 * radius, 2 * radius); } } And I dont know how to use code tag.so plz someone ans.

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  • Second Thread Holding Up Entire Program in C# Windows Form Application

    - by Brandon
    In my windows form application, I'm trying to test the user's ability to access a remote machine's shared folder. The way I'm doing this (and I'm sure that there are better ways...but I don't know of them) is to check for the existence of a specific directory on the remote machine (I'm doing this because of firewall/other security restrictions that I'm confronted with in my organization). If the user has rights to access the shared folder, then it returns in no time at all, but if they don't, it hangs forever. To solve this, I threw the check into another thread and wait only 1000 milliseconds before determining that the share can't be hit by the user. However, when I do this, it still hangs as if it was never run in the same thread. What is making it hang and how do I fix it? I would think that the fact that it is in a separate thread would allow me to just let the thread finish on it's own in the background. Here is my code: bool canHitInstallPath = false; Thread thread = new Thread(new ThreadStart(() => { canHitInstallPath = Directory.Exists(compInfo.InstallPath); })); thread.Start(); thread.Join(1000); if (canHitInstallPath == false) { throw new Exception("Cannot hit folder: " + compInfo.InstallPath); }

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  • make a thread which recieves values from other threads

    - by farteaga88
    This program in Java creates a list of 15 numbers and creates 3 threads to search for the maximum in a given interval. I want to create another thread that takes those 3 numbers and get the maximum. but i don't know how to get those values in the other thread. public class apple implements Runnable{ String name; int time, number, first, last, maximum; int[] array = {12, 32, 54 ,64, 656, 756, 765 ,43, 34, 54,5 ,45 ,6 , 5, 65}; public apple(String s, int f, int l){ name = s; first = f; last = l; maximum = array[0]; } public void run(){ try{ for(int i = first; i < last; i++ ) { if(maximum < array[i]) { maximum = array[i]; } } System.out.println("Thread"+ name + "maximum = " + maximum); }catch(Exception e){} } public static void main(String[] args){ Thread t1 = new Thread(new apple("1 ", 0, 5)); Thread t2 = new Thread(new apple("2 ", 5, 10 )); Thread t3 = new Thread(new apple("3 ", 10, 15)); try{ t1.start(); t2.start(); t3.start(); }catch(Exception e){} } }

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  • Various way to stop a thread - which is the correct way

    - by Yan Cheng CHEOK
    I had came across different suggestion of stopping a thread. May I know, which is the correct way? Or it depends? Using Thread Variable http://download.oracle.com/javase/1.4.2/docs/guide/misc/threadPrimitiveDeprecation.html private volatile Thread blinker; public void stop() { blinker = null; } public void run() { Thread thisThread = Thread.currentThread(); while (blinker == thisThread) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } } Using boolean flag private volatile boolean flag; public void stop() { flag = false; } public void run() { while (flag) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } } Using Thread Variable together with interrupt private volatile Thread blinker; public void stop() { blinker.interrupt(); blinker = null; } public void run() { Thread thisThread = Thread.currentThread(); while (!thisThread.isInterrupted() && blinker == thisThread) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } }

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  • 500.19 error NetBios command limit thread on forums.iis.net

    - by The Official Microsoft IIS Site
    Here is a great thread on how a person reported fixing a problem 500.19 error NetBios command limit and using a UNC based content architecture. http://forums.iis.net/p/1165964/1937935.aspx http://download.microsoft.com/download/7/4/f/74fe970d-4a7d-4034-9f5d-02572567e7f7/24_CHAPTER_11_Troubleshooting_IIS_6.0.doc http://support.microsoft.com/kb/813776 Check out the UNC tag regarding others that have great information. http://weblogs.asp.net/steveschofield/archive/tags/UNC/default.aspx Steve Schofield...(read more)

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  • 500.19 error NetBios command limit thread on forums.iis.net

    - by steve schofield
    Here is a great thread on how a person reported fixing a problem 500.19 error NetBios command limit and using a UNC based content architecture. http://forums.iis.net/p/1165964/1937935.aspx http://download.microsoft.com/download/7/4/f/74fe970d-4a7d-4034-9f5d-02572567e7f7/24_CHAPTER_11_Troubleshooting_IIS_6.0.doc http://support.microsoft.com/kb/813776 Check out the UNC tag regarding others that have great information. http://weblogs.asp.net/steveschofield/archive/tags/UNC/default.aspx Steve SchofieldMicrosoft MVP - IIS

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  • Per-Thread Visibility PHPBB

    - by Andrei Krotkov
    I'm trying to implement a registration system for a board I'm running, and I want a forum where every thread is invisible to everyone but the person who started it and the moderator staff. I want the staff to be able to post and for the person registering to respond, but I haven't been able to find a per-post visibility solution. Are there any mods that perform this task, or is there a hidden setting in the software somewhere?

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  • PCI-e SEALEVEL dual serial card not recognized on Ubuntu 14.04

    - by kwhunter
    New to Ubuntu, running 14.04. I have trouble with the serial port setup, I have a plug-in PCI-e SEALEVEL dual serial card that is not recognized. user1@WSIWORKSTATION2:~$ dmesg | grep tty [ 0.000000] console [tty0] enabled [ 1.577197] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A [ 1.943326] tty ttyprintk: hash matches [ 17.240880] ttyS4: LSR safety check engaged! [ 17.241589] ttyS4: LSR safety check engaged! [ 17.242354] ttyS5: LSR safety check engaged! [ 17.243058] ttyS5: LSR safety check engaged! [ 17.243918] ttyS6: LSR safety check engaged! [ 17.244485] ttyS6: LSR safety check engaged! [ 17.245195] ttyS7: LSR safety check engaged! [ 17.245830] ttyS7: LSR safety check engaged! [ 17.246554] ttyS8: LSR safety check engaged! [ 17.247191] ttyS8: LSR safety check engaged! user1@WSIWORKSTATION2:~/Desktop/seacom$ lspci -d 135e: -vvv 02:04.0 Bridge: Sealevel Systems Inc Device e205 (rev aa) Subsystem: Sealevel Systems Inc Device e205 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx- Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium TAbort- SERR- Capabilities: However, the manufacturer's drivers won't install: 1. user1@WSIWORKSTATION2:~/Desktop/seacom$ make install ---------------------------------------------------------------- Installing seacom suite. ---------------------------------------------------------------- --Installing utilities-- /usr/bin/ld: skipping incompatible ../../lib/libftd2xx.a when searching for -lftd2xx /usr/bin/ld: cannot find -lftd2xx collect2: error: ld returned 1 exit status make[2]: *** [setusb] Error 1 make[1]: *** [install] Error 1 make: *** [install] Error 1 2. user1@WSIWORKSTATION2:~/Desktop/seaio$ make install ---------------------------------------------------------------- Installing SD suite. ---------------------------------------------------------------- *Compiling SeaIO Library source file: digitalIoDevice.cpp gcc: error trying to exec 'cc1plus': execvp: No such file or directory make[1]: *** [digitalIoDevice.o] Error 1 make: *** [install] Error 1 I was not able to find a solution, so if anyone can help it will be much appreciated. PS Have some troubles with formatting my post, apologies...

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  • Unintentional run-in with C# thread concurrency

    - by geekrutherford
    For the first time today we began conducting load testing on a ASP.NET application already in production. Obviously you would normally want to load test prior to releasing to a production environment, but that isn't the point here.   We ran a test which simulated 5 users hitting the application doing the same actions simultaneously. The first few pages visited seemed fine and then things just hung for a while before the test failed. While the test was running I was viewing the performance counters on the server noting that the CPU was consistently pegged at 100% until the testing tool gave up.   Fortunately the application logs all exceptions including those unhandled to the database (thanks to log4net). I checked the log and low and behold the error was:   System.ArgumentException: An item with the same key has already been added. (The rest of the stack trace intentionally omitted)   Since the code was running with debug on the line number where the exception occured was also provided. I began inspecting the code and almost immediately it hit me, the section of code responsible for the exception is trying to initialize a static class. My next question was how is this code being hit multiple times when I have a rudimentary check already in place to prevent this kind of thing (i.e. a check on a public variable of the static class before entering the initializing routine). The answer...the check fails because the value is not set before other threads have already made it through.   Not being one who consistently works with threading I wasn't quite sure how to handle this problem. Fortunately a co-worker recalled having to lock a section of code in the past but couldn't recall exactly how. After a quick search on Google the solution is as follows:   Object objLock = new Object(); lock(objLock) { //logic requiring lock }   The lock statement takes an object and tells the .NET runtime that the current thread has exclusive access while the code within brackets is executing. Once the code completes, the lock is released for another thread to utilize.   In my case, I only need to execute the inner code once to initialize my static class. So within the brackets I have a check on a public variable to prevent it from being initialized again.

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  • Use Thread-local Storage to Reduce Synchronization

    Synchronization is often an expensive operation that can limit the performance of a multithreaded program. Using thread-local data structures instead of data structures shared by the threads can reduce synchronization in certain cases, allowing a program to run faster.

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  • Java Generics Type Safety warning with recursive Hashmap

    - by GC
    Hi, I'm using a recursive tree of hashmaps, specifically Hashmap map where Object is a reference to another Hashmap and so on. This will be passed around a recursive algorithm: foo(String filename, Hashmap<String, Object> map) { //some stuff here for (Entry<String, Object> entry : map.entrySet()) { //type warning that must be suppressed foo(entry.getKey(), (HashMap<String, Object>)entry.getValue()); } } I know for sure Object is of type Hashmap<String, Object> but am irritated that I have to suppress the warning using @SuppressWarnings("unchecked"). I'll be satisfied with a solution that does either a assert(/*entry.getValue() is of type HashMap<String, Object>*/) or throws an exception when it isn't. I went down the Generics route for compile type safety and if I suppress the warning then it defeats the purpose. Thank you for your comments, ksb

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  • C# - Which is more efficient and thread safe? static or instant classes?

    - by Soni Ali
    Consider the following two scenarios: //Data Contract public class MyValue { } Scenario 1: Using a static helper class. public class Broker { private string[] _userRoles; public Broker(string[] userRoles) { this._userRoles = userRoles; } public MyValue[] GetValues() { return BrokerHelper.GetValues(this._userRoles); } } static class BrokerHelper { static Dictionary<string, MyValue> _values = new Dictionary<string, MyValue>(); public static MyValue[] GetValues(string[] rolesAllowed) { return FilterForRoles(_values, rolesAllowed); } } Scenario 2: Using an instance class. public class Broker { private BrokerService _service; public Broker(params string[] userRoles) { this._service = new BrokerService(userRoles); } public MyValue[] GetValues() { return _service.GetValues(); } } class BrokerService { private Dictionary<string, MyValue> _values; private string[] _userRoles; public BrokerService(string[] userRoles) { this._userRoles = userRoles; this._values = new Dictionary<string, MyValue>(); } public MyValue[] GetValues() { return FilterForRoles(_values, _userRoles); } } Which of the [Broker] scenarios will scale best if used in a web environment with about 100 different roles and over a thousand users. NOTE: Feel free to sugest any alternative approach.

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  • [Java] - Problem having my main thread sleeping

    - by Chris
    I'm in a Java class and our assignment is to let us explore threads in Java. So far so good except for this one this one problem. And I believe that could be because of my lack of understanding how Java threads work at the moment. I have the main thread of execution which spawns new threads. In the main thread of execution in main() I am calling Thread.sleep(). When I do I get an Unhandled exception type InterruptedException. I am unsure of why I am getting this? I thought this was because I needed a reference to the main thread so I went ahead and made a reference to it via Thread.currentThread(). Is this not the way to have the thread sleep? What I need to do is have the main thread wait/sleep/delay till it does it required work again. Any help would be much appreciated.

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  • Thread Local Storage and local method variables

    - by miguel
    In c#, each thread has its own stack space. If this is the case, why is the following code not thread-safe? (It is stated that this code is thread-safe on this post: Locking in C# class Foo { private int count = 0; public void TrySomething() { count++; } } As count is an int (stack variable), surely this value would be isolated to an individual thread, on its own stack, and therefore thread-safe? I am probably missing something here, but I dont understand what is actually in Thread Local Storage if not stack-based variables for the thread?

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  • How to correctly stop thread which is using Control.Invoke

    - by codymanix
    I tried the following (pseudocode) but I always get a deadlock when Iam trying to stop my thread. The problem is that Join() waits for the thread to complete and a pending Invoke() operation is also waiting to complete. How can I solve this? Thread workerThread = new Thread(BackupThreadRunner); volatile bool cancel; // this is the thread worker routine void BackupThreadRunner() { while (!cancel) { DoStuff(); ReportProgress(); } } // main thread void ReportProgress() { if (InvokeRequired) { Invoke(ReportProgress); } UpdateStatusBarAndStuff(); } // main thread void DoCancel() { cancel=true; workerThread.Join(); }

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  • Java: serial thread confinement question

    - by denis
    Assume you have a Collection(ConcurrentLinkedQueue) of Runnables with mutable state. Thread A iterates over the Collection and hands the Runnables to an ExecutorService. The run() method changes the Runnables state. The Runnable has no internal synchronization. The above is a repetitive action and the worker threads need to see the changes made by previous iterations. So a Runnable gets processed by one worker thread after another, but is never accessed by more than one thread at a time - a case of serial thread confinement(i hope ;)). The question: Will it work just with the internal synchronization of the ConcurrentLinkedQueue/ExecutorSerivce? To be more precise: If Thread A hands Runnable R to worker thread B and B changes the state of R, and then A hands R to worker thread C..does C see the modifications done by B?

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  • c style thread creation in python

    - by chandank
    Hi I am new to python and want to create multiple threads in a loop something like (in C style) for (;i < 10; i++) thread[i]= pthread_create(&thread[i],&attr,func) I am not sure how to do the same in python? Basically I want have that thread[] variable as global will create all thread at once and then will start then in once. I have written a similar python program that does it but I think having it in above style will be better. def thread_create(thread_number): command_string = "Thread-" + "%d" %thread_number thread = myThread(thread_number, command_string) thread.start() # Start new Threads for i in range(5): thread_create(i)

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  • Java Thread Message Passing

    - by pkulak
    I'm writing an Android app. I have a main method, which creates and runs a new Thread using an anonymous inner Runnable class. The run() method, when it's done, calls a method on it's parent class (in the main thread) that calls notifyDataSetChanged() so that the main thread can redraw the new data. This is causing all kinds of trouble (ViewRoot$CalledFromWrongThreadException). The thing is, this method being called from the worker thread is on the class that's created in the UI thread. Shouldn't that be running on the UI thread? Or am I missing something? Here's some code about what I'm talking about: public class Mealfire extends Activity { @Override public void onCreate(Bundle icicle) { (new Thread() { public void run() { // Do a bunch of slow network stuff. update(); } }).start(); } private void update() { myAdapter.notifyDatasetChanged(); } }

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  • Does SetThreadPriority cause thread reschedulling?

    - by Suma
    Consider following situation, assuming single CPU system: thread A is running with a priority THREAD_PRIORITY_NORMAL, signals event E thread B with a priority THREAD_PRIORITY_LOWEST is waiting for an event E (Note: at this point the thread is not scheduled because it is runnable, but A is higher priority and runnable as well) thread A calls SetThreadPriority(B, THREAD_PRIORITY_ABOVE_NORMAL) Is thread B re-scheduled immediately to run, or is thread A allowed to continue until current time-slice is over, and B is scheduled only once a new time-slice has begun? I would be interested to know the answer for WinXP, Vista and Win7, if possible. Note: the scenario above is simplified from my real world code, where multiple threads are running on multiple cores, but the main object of the question stays: does SetThreadPriority cause thread scheduling to happen?

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  • Call an AsyncTask inside a Thread

    - by Arun
    I am working in an android application and I want to call an AsyncTask from my UI main thread. For that I want to call my AsyncTask from a thread. This is the method that I call from my main UI thread. This is working correctly CommonAysnk mobjCommonAysnk = new CommonAysnk(this, 1); mobjCommonAysnk.execute(); CommonAysnk is my AsyncTask class.I want to pass my activity and an integer parameter to the AsyncTask constructor. How can I call this from a thread as shown below method. Thread t = new Thread() { public void run() { try { CommonAysnk mobjCommonAysnk = new CommonAysnk(this, 1); mobjCommonAysnk.execute(); } catch (Exception ex) { }}}; t.start(); When I tried to call it from a Thread and I am not able to pass the activity parameter correctly. How can we sole this. Thanks

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  • ADO.NET DataTable/DataRow Thread Safety

    - by Allen E. Scharfenberg
    Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

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