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• Graceful termination of NSApplication with Core Data and Grand Central Dispatch (GCD)

  - by Vincent Mac

  I have an Cocoa Application (Mac OS X SDK 10.7) that is performing some processes via Grand Central Dispatch (GCD). These processes are manipulating some Core Data NSManagedObjects (non-document-based) in a manner that I believe is thread safe (creating a new managedObjectContext for use in this thread). The problem I have is when the user tries to quit the application while the dispatch queue is still running. The NSApplication delegate is being called before actually quitting. - (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender I get an error "Could not merge changes." Which is somewhat expected since there are still operations being performed through the different managedObjectContext. I am then presented with the NSAlert from the template that is generated with a core data application. In the Threading Programming Guide there is a section called "Be Aware of Thread Behaviors at Quit Time" which alludes to using replyToApplicationShouldTerminate: method. I'm having a little trouble implementing this. What I would like is for my application to complete processing the queued items and then terminate without presenting an error message to the user. It would also be helpful to update the view or use a sheet to let the user know that the app is performing some action and will terminate when the action is complete. Where and how would I implement this behavior?

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• Run a .java file using ProcessBuilder

  - by David K

  I'm a novice programmer working in Eclipse, and I need to get multiple processes running (this is going to be a simulation of a multi-computer system). My initial hackup used multiple threads to multiple classes, but now I'm trying to replace the threads with processes. From my reading, I've gleaned that ProcessBuilder is the way to go. I have tried many many versions of the input you see below, but cannot for the life of me figure out how to properly use it. I am trying to run the .java files I previously created as classes (which I have modified). I eventually just made a dummy test.java to make sure my process is working properly - its only function is to print that it ran. My code for the two files are below. Am I using ProcessBuilder correctly? Is this the correct way to read the output of my subprocess? Any help would be much appreciated. David primary process package Control; import java.io.*; import java.lang.*; public class runSPARmatch { /** * @param args */ public static void main(String args[]) { try { ProcessBuilder broker = new ProcessBuilder("javac.exe","test.java","src\\Broker\\"); Process runBroker = broker.start(); Reader reader = new InputStreamReader(runBroker.getInputStream()); int ch; while((ch = reader.read())!= -1) System.out.println((char)ch); reader.close(); runBroker.waitFor(); System.out.println("Program complete"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } subprocess package Broker; public class test { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("This works"); } }

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• Architecture Guidance Needed?

  - by vijay

  We are about to automate number of process for our reporting team. (The reports are like daily reports, weekly reports, monthly reports, etc..) Mostly the process is like pulling some data from the oracle and then fill them in particular excel template files. Each reports and so their templates are different from each other. Except the excel file manipulation, there are hardly any business logic behind these. Client wanted an integrated tool and all the automated processes are placed as menus/submenus. Right now roughly there are around 30 process waiting to be automated. And we are expecting more new reports in the next quarter. I am nowhere to near having any practical experience when comes to architecuring. Already i have been maintaining two or three systems(they are more than 4yrs old.) for this prestegious client.The possiblity of the above mentioned tool will be manintained for another 3 yrs is very likely. From my past experience i've been through the pain of implmenting change requests to the rigd & undocumented code base resulting in the break down of the system and then eventually myself. So My main and top most concern is the maintainablity. When i was searching for these i came across this link, Smart Clients Using CAB and SCSF is the above link appropriate for my requirement? Also Should i place each automated processes in separate forms under a single project, or place them in separate projects under a single solution.. Please correct me if have missed any other important information. Thx.

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• NonStop ODBC: how the connections (ODBC servers) are assigned to CPUs?

  - by Vladimir Dyuzhev

  We have an ODBC pool running on a NonStop server. The pool is connected to SQL/MX. This pool is used by a few external Java applications, each of which has an JDBC pool connected to ODBC pool (e.g. 14 connections per application). With time (after a few application recycles) we see an imbalance between CPUs -- some have 8 ODBC processes running, some only 5. That leads to CPU time imbalance too. Up to this point we assumed that a CPU is assigned to ODBC process in round-robin fashion. That would maintain the number of ODBC processes more or less equally distributed. It's not the case though. Is there any information on how ODBC pool decided which CPU to choose for every new allocated process? Does it look at CPU load? Available memory? Something else? Sadly, even HP's own people (available to us, that is) couldn't answer those questions with certainty. :-(

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• what webserver / mod / technique should I use to serve everything from memory?

  - by reinier

  I've lots of lookuptables from which I'll generate my webresponse. I think IIS with Asp.net enables me to keep static lookuptables in memory which I can use to serve up my responses very fast. Are there however also non .net solutions which can do the same? I've looked at fastcgi, but I think this starts X processes, of which anyone can handle Y requests. But the processes are by definition shielded from eachother. I could configure fastcgi to use just 1 process, but does this have scalability implications? anything using PHP or any other interpreted language won't fly because it is also cgi or fastcgi bound right? I understand memcache could be an option, though this would require another (local) socket connection which I'd rather avoid since everything in memory would be much faster. The solution can work under WIndows or Unix... it doesn't matter too much. The only thing which matters is that there will be a lot of requests (100/sec now and growing to 500/sec in a year), and I want to reduce the amount of webservers needed to process it. The current solution is done using PHP and memcache (and the occasional hit to the SQL server backend). Although it is fast (for php anyway), Apache has real problems when the 50/sec is passed. I've put a bounty on this question since I've not seen enough responses to make a wise choice. At the moment I'm considering either Asp.net or fastcgi with C(++).

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• S3 Backup Memory Usage in Python

  - by danpalmer

  I currently use WebFaction for my hosting with the basic package that gives us 80MB of RAM. This is more than adequate for our needs at the moment, apart from our backups. We do our own backups to S3 once a day. The backup process is this: dump the database, tar.gz all the files into one backup named with the correct date of the backup, upload to S3 using the python library provided by Amazon. Unfortunately, it appears (although I don't know this for certain) that either my code for reading the file or the S3 code is loading the entire file in to memory. As the file is approximately 320MB (for today's backup) it is using about 320MB just for the backup. This causes WebFaction to quit all our processes meaning the backup doesn't happen and our site goes down. So this is the question: Is there any way to not load the whole file in to memory, or are there any other python S3 libraries that are much better with RAM usage. Ideally it needs to be about 60MB at the most! If this can't be done, how can I split the file and upload separate parts? Thanks for your help. This is the section of code (in my backup script) that caused the processes to be quit: filedata = open(filename, 'rb').read() content_type = mimetypes.guess_type(filename)[0] if not content_type: content_type = 'text/plain' print 'Uploading to S3...' response = connection.put(BUCKET_NAME, 'daily/%s' % filename, S3.S3Object(filedata), {'x-amz-acl': 'public-read', 'Content-Type': content_type})

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• Storing an object to use in multiple classes

  - by Aaron Sanders

  I am wondering the best way to store an object in memory that is used in a lot of classes throughout an application. Let me set up my problem for you: We have multiple databases, 1 per customer. We also have a master table and each row is detailed information about the databases such as database name, server IP it's located and a few config settings. I have an application that loops through those multiple databases and runs some updates on them. The settings I mentioned above are updated each loop iteration into memory. The application then runs through series of processes that include multiple classes using this data. The data never changes during the processes, only during the loop iteration. The variables are related to a customer, so I have them stored in a customer class. I suppose I could make all of the members shared or should I use a singleton for the customer class? I've never actually used a singleton, only read they are good in this type of situation. Are there better solutions to this type of scenario? Also, I could have plans for this application to be multithreaded later. Sorry if this is confusing. If you have questions, let me know and I will answer them. Thanks for your help.

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• SQL Concurrent test update question

  - by ptoinson

  Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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• linux new/delete, malloc/free large memory blocks

  - by brian_mk

  Hi folks, We have a linux system (kubuntu 7.10) that runs a number of CORBA Server processes. The server software uses glibc libraries for memory allocation. The linux PC has 4G physical memory. Swap is disabled for speed reasons. Upon receiving a request to process data, one of the server processes allocates a large data buffer (using the standard C++ operator 'new'). The buffer size varies depening upon a number of parameters but is typically around 1.2G Bytes. It can be up to about 1.9G Bytes. When the request has completed, the buffer is released using 'delete'. This works fine for several consecutive requests that allocate buffers of the same size or if the request allocates a smaller size than the previous. The memory appears to be free'd ok - otherwise buffer allocation attempts would eventually fail after just a couple of requests. In any case, we can see the buffer memory being allocated and freed for each request using tools such as KSysGuard etc. The problem arises when a request requires a buffer larger than the previous. In this case, operator 'new' throws an exception. It's as if the memory that has been free'd from the first allocation cannot be re-allocated even though there is sufficient free physical memory available. If I kill and restart the server process after the first operation, then the second request for a larger buffer size succeeds. i.e. killing the process appears to fully release the freed memory back to the system. Can anyone offer an explanation as to what might be going on here? Could it be some kind of fragmentation or mapping table size issue? I am thinking of replacing new/delete with malloc/free and use mallopt to tune the way the memory is being released to the system. BTW - I'm not sure if it's relevant to our problem, but the server uses Pthreads that get created and destroyed on each processing request. Cheers, Brian.

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• How to cache pages using background jobs ?

  - by Alexandre

  Definitions: resource = collection of database records, regeneration = processing these records and outputting the corresponding html Current flow: Receive client request Check for resource in cache If not in cache or cache expired, regenerate Return result The problem is that the regeneration step can tie up a single server process for 10-15 seconds. If a couple of users request the same resource, that could result in a couple of processes regenerating the exact same resource simultaneously, each taking up 10-15 seconds. Wouldn't it be preferrable to have the frontend signal some background process saying "Hey, regenerate this resource for me". But then what would it display to the user? "Rebuilding" is not acceptable. All resources would have to be in cache ahead of time. This could be a problem as the database would almost be duplicated on the filesystem (too big to fit in memory). Is there a way to avoid this? Not ideal, but it seems like the only way out. But then there's one more problem. How to keep the same two processes from requesting the regeneration of a resource at the same time? The background process could be regenerating the resource when a frontend asks for the regeneration of the same resource. I'm using PHP and the Zend Framework just in case someone wants to offer a platform-specific solution. Not that it matters though - I think this problem applies to any language/framework. Thanks!

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• Writing/Reading struct w/ dynamic array through pipe in C

  - by anrui

  I have a struct with a dynamic array inside of it: struct mystruct{ int count; int *arr; }mystruct_t; and I want to pass this struct down a pipe in C and around a ring of processes. When I alter the value of count in each process, it is changed correctly. My problem is with the dynamic array. I am allocating the array as such: mystruct_t x; x.arr = malloc( howManyItemsDoINeedToStore * sizeof( int ) ); Each process should read from the pipe, do something to that array, and then write it to another pipe. The ring is set up correctly; there's no problem there. My problem is that all of the processes, except the first one, are not getting a correct copy of the array. I initialize all of the values to, say, 10 in the first process; however, they all show up as 0 in the subsequent ones. for( j = 0; j < howManyItemsDoINeedToStore; j++ ){ x.arr[j] = 10; } Initally: 10 10 10 10 10 After Proc 1: 9 10 10 10 15 After Proc 2: 0 0 0 0 0 After Proc 3: 0 0 0 0 0 After Proc 4: 0 0 0 0 0 After Proc 5: 0 0 0 0 0 After Proc 1: 9 10 10 10 15 After Proc 2: 0 0 0 0 0 After Proc 3: 0 0 0 0 0 After Proc 4: 0 0 0 0 0 After Proc 5: 0 0 0 0 0 Now, if I alter my code to, say, struct mystruct{ int count; int arr[10]; }mystruct_t; everything is passed correctly down the pipe, no problem. I am using READ and WRITE, in C: write( STDOUT_FILENO, &x, sizeof( mystruct_t ) ); read( STDIN_FILENO, &x, sizeof( mystruct_t ) ); Any help would be appreciated. Thanks in advance!

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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• How to perform undirected graph processing from SQL data

  - by recipriversexclusion

  I ran into the following problem in dynamically creating topics for our ActiveMQ system: I have a number of processes (M_1, ..., M_n), where n is not large, typically 5-10. Some of the processes will listen to the output of others, through a message queue; these edges are specified in an XML file, e.g. <link from="M1" to="M3"</link> <link from="M2" to="M4"</link> <link from="M3" to="M4"</link> etc. The edges are sparse, so there won't be many of them. I will parse this XML and store this information in an SQL DB, one table for nodes and another for edges. Now, I need to dynamically create strings of the form M1.exe --output_topic=T1 M2.exe --output_topic=T2 M3.exe --input_topic=T1 --output_topic=T3 M4.exe --input_topic=T2 --input_topic=T3 where the tags are sequentially generated. What is the best way to go about querying SQL to obtain these relationships? Are there any tools or other tutorials you can point me to? I've never done graps with SQL. Using SQL is imperative, because we use it for other stuff, too. Thanks!

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• confusing fork system call

  - by benjamin button

  Hi, i was just checking the behaviour of fork system call and i found it very confusing. i saw in a website that Unix will make an exact copy of the parent's address space and give it to the child. Therefore, the parent and child processes have separate address spaces #include <stdio.h> #include <sys/types.h> int main(void) { pid_t pid; char y='Y'; char *ptr; ptr=&y; pid = fork(); if (pid == 0) { y='Z'; printf(" *** Child process ***\n"); printf(" Address is %p\n",ptr); printf(" char value is %c\n",y); sleep(5); } else { sleep(5); printf("\n ***parent process ***\n",&y); printf(" Address is %p\n",ptr); printf(" char value is %c\n",y); } } the output of the above program is : *** Child process *** Address is 69002894 char value is Z ***parent process *** Address is 69002894 char value is Y so from the above mentioned statement it seems that child and parent have separet address spaces.this is the reason why char value is printed separately and why am i seeing the address of the variable as same in both child and parent processes.? Please help me understand this!

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• Divide and conquer of large objects for GC performance

  - by Aperion

  At my work we're discussing different approaches to cleaning up a large amount of managed ~50-100MB memory.There are two approaches on the table (read: two senior devs can't agree) and not having the experience the rest of the team is unsure of what approach is more desirable, performance or maintainability. The data being collected is many small items, ~30000 which in turn contains other items, all objects are managed. There is a lot of references between these objects including event handlers but not to outside objects. We'll call this large group of objects and references as a single entity called a blob. Approach #1: Make sure all references to objects in the blob are severed and let the GC handle the blob and all the connections. Approach #2: Implement IDisposable on these objects then call dispose on these objects and set references to Nothing and remove handlers. The theory behind the second approach is since the large longer lived objects take longer to cleanup in the GC. So, by cutting the large objects into smaller bite size morsels the garbage collector will processes them faster, thus a performance gain. So I think the basic question is this: Does breaking apart large groups of interconnected objects optimize data for garbage collection or is better to keep them together and rely on the garbage collection algorithms to processes the data for you? I feel this is a case of pre-optimization, but I do not know enough of the GC to know what does help or hinder it.

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• How to run the HelloWorld ODE from the browser?

  - by tikky

  I develop a simple hello world project by using Eclipse IDE. I can run it from the IDE (Web Services - Test with Web Services Explorer). From that it work perfectly, but if I try to access the http://localhost:8080/ode/processes/HelloWorld/ It gives some exceptions. org.apache.axis2.AxisFault: The endpoint reference (EPR) for the Operation not found is /ode/processes/HelloWorld/ and the WSA Action = null at org.apache.axis2.engine.DispatchPhase.checkPostConditions(DispatchPhase.java:86) at org.apache.axis2.engine.Phase.invoke(Phase.java:308) at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:212) at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:132) at org.apache.axis2.transport.http.util.RESTUtil.invokeAxisEngine(RESTUtil.java:125) at org.apache.axis2.transport.http.util.RESTUtil.processURLRequest(RESTUtil.java:119) at org.apache.axis2.transport.http.AxisServlet$RestRequestProcessor.processURLRequest(AxisServlet.java:799) at org.apache.axis2.transport.http.AxisServlet.doGet(AxisServlet.java:242) at org.apache.ode.axis2.hooks.ODEAxisServlet.doGet(ODEAxisServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:729) What may be the issue and how to develop it as, input values through the web browser and get the output from it. Thank you.

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• First could access the repository next cannot

  - by Banani

  Hi! I have configured svnserve (1.6.5,plain, without apache) on Fedora 12. I could ran the following svn subcommands which access the repository after configuration. Such as, commit, update,checkout, list. But, when next time ( after stopping,ctrl-c and then starting svnserve)I tried above commands, could not access the repository. This is happening both from local and remote machine. I ran svn and svnserve as below. 'svn commit svn://127.0.0.1/myrepository/' from local client. 'svnserve -d --foregorund --listen-port=3690 -r /path-to-repository/mypository/' To understand the problem better, I created another repository and found similar behavior . Frist I could access the repository and next I could not. I tried doing strace on svnserve, but don't uderstand much of it. Below is the partial output. accept(3, {sa_family=AF_INET, sin_port=htons(54425), sin_addr=inet_addr("127.0.0 .1")}, [16]) = 4 fcntl64(4, F_GETFD) = 0 fcntl64(4, F_SETFD, FD_CLOEXEC) = 0 waitpid(-1, 0xbfcdf31c, WNOHANG|WSTOPPED) = -1 ECHILD (No child processes) clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, chil d_tidptr=0xb7743758) = 9737 close(4) = 0 accept(3, 0xbfcdf2bc, [128]) = ? ERESTARTSYS (To be restarted) --- SIGCHLD (Child exited) @ 0 (0) --- sigreturn() = ? (mask now []) waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WNOHANG|WSTOPPED) = 9737 waitpid(-1, 0xbfcdf31c, WNOHANG|WSTOPPED) = -1 ECHILD (No child processes) My question: Why user are not able to access the repository anymore? What information the strace output gives about this problem? Any help is much appreciated. Thanks. Banani

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• Shared Memory and Process Sempahores (IPC)

  - by fsdfa

  This is an extract from Advanced Liniux Programming: Semaphores continue to exist even after all processes using them have terminated. The last process to use a semaphore set must explicitly remove it to ensure that the operating system does not run out of semaphores.To do so, invoke semctl with the semaphore identifier, the number of semaphores in the set, IPC_RMID as the third argument, and any union semun value as the fourth argument (which is ignored).The effective user ID of the calling process must match that of the semaphore’s allocator (or the caller must be root). Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately. If a process allocate a shared memory, and many process use it and never set to delete it (with shmctl), if all them terminate, then the shared page continues being available. (We can see this with ipcs). If some process did the shmctl, then when the last process deattached, then the system will deallocate the shared memory. So far so good (I guess, if not, correct me). What I dont understand from that quote I did, is that first it say: "Semaphores continue to exist even after all processes using them have terminated." and then: "Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately."

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• Disadvantages of MySQL Row Locking

  - by Nyxynyx

  I am using row locking (transactions) in MySQL for creating a job queue. Engine used is InnoDB. SQL Query START TRANSACTION; SELECT * FROM mytable WHERE status IS NULL ORDER BY timestamp DESC LIMIT 1 FOR UPDATE; UPDATE mytable SET status = 1; COMMIT; According to this webpage, The problem with SELECT FOR UPDATE is that it usually creates a single synchronization point for all of the worker processes, and you see a lot of processes waiting for the locks to be released with COMMIT. Question: Does this mean that when the first query is executed, which takes some time to finish the transaction before, when the second similar query occurs before the first transaction is committed, it will have to wait for it to finish before the query is executed? If this is true, then I do not understand why the row locking of a single row (which I assume) will affect the next transaction query that would not require reading that locked row? Additionally, can this problem be solved (and still achieve the effect row locking does for a job queue) by doing a UPDATE instead of the transaction? UPDATE mytable SET status = 1 WHERE status IS NULL ORDER BY timestamp DESC LIMIT 1

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• Solaris MySQL Unable to start successfully

  - by Iscariot

  Environment: Solaris 10 This mysql server has been up and running for 6 months now. Today all of a sudden it crashed. When typing 'mysql' as user it gives the error MYSQL" Error 2002 (HY000): Can't Connect to Local MySQL server though socket '/tmp/mysql.sock' when typing mysql as root it says mysql: not found. The server try to open mysql, it stays open for 9-10 seconds and restarts the process. Below are the application logs. Application-database-mysql_mysql-csk.log [ May 30 22:37:52 Enabled. ] [ May 30 22:37:58 Rereading configuration. ] [ May 30 22:37:59 Executing start method ("/opt/coolstack/lib/svc/method/svc-cskmysql start") ] /opt/coolstack/mysql/bin/mysqld_safe --user=mysql --datadir=/dbpool1/data --pid-file=/dbpool1/data/database.soliaonline.com.pid [ May 30 22:37:59 Method "start" exited with status 0 ] [ May 30 22:38:13 Stopping because all processes in service exited. ] [ May 30 22:38:13 Executing stop method ("/opt/coolstack/lib/svc/method/svc-cskmysql stop") ] [ May 30 22:38:13 Method "stop" exited with status 0 ] [ May 30 22:38:13 Executing start method ("/opt/coolstack/lib/svc/method/svc-cskmysql start") ] /opt/coolstack/mysql/bin/mysqld_safe --user=mysql --datadir=/dbpool1/data --pid-file=/dbpool1/data/database.soliaonline.com.pid [ May 30 22:38:13 Method "start" exited with status 0 ] [ May 30 22:38:25 Stopping because all processes in service exited. ] [ May 30 22:38:25 Executing stop method ("/opt/coolstack/lib/svc/method/svc-cskmysql stop") ] [ May 30 22:38:25 Method "stop" exited with status 0 ] I am hoping someone might have run into this before and might know how to fix it.

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• Python Multiprocessing Question

  - by Avan

  My program has 2 parts divided into the core and downloader. The core handles all the app logic while the downloader just downloads urls. Right now, I am trying to use the python multiprocessing module to accomplish the task of the core as a process and the downloader as a process. The first problem I noticed was that if I spawn the downloader process from the core process so that the downloader is the child process and the core is the parent, the core process(parent) is blocked until the child is finished. I do not want this behaivor though. I would like to have a core process and a downloader process that are both able to execute their code and communicate between each other. example ... def main(): jobQueue = Queue() jobQueue.put("http://google.com) d = Downloader(jobQueue) p = Process(target=d.start()) p.start() if __name__ == '__main__': freeze_support() main() where Downloader's start() just takes the url out of the queue and downloads it. In order to have the 2 processes unblocked, would I need to create 2 processes from the parent process and then share something between them?

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• Distributed Cache with Serialized File as DataStore in Oracle Coherence

  - by user226295

  Weired but I am investigating the Oracle Coherence as a substitue for distribute cache. My primarr problem is that we dont have distribituted cache as such as of now in our app. Thats my major concern. And thats what I want to implement. So, lets say if I take up a machine and start a new (3rd) reading process, it will be able to connect to the cache and listen to the cache and will have a full set of cache triplicated (as of now its duplicated) Now thats waste from a common person stanpoint too. The size of the cache is 2 GB and without going distibuted its limiting us. Thats bring me to Coheremce. But now, we dont have database as persistent store too. we have the archival processes as our persistent store. (90 days worth of data) Ok now multiply that with soem where around 2 GB * 90 (thats the bare minimum we want to keep). Preliminary/Intermediate analysis of Coherence as a solution. And a (supposedly) brilliant thought crossed my mind. Why not have this as persistant storage with my distributed cache. Does Oracle Coherence support that. I will get rid of archiving infrastructure too (i hate daemon archiving processes). For some starnge reasons, I dont wanna go to the DB to replace those flat files. What say?, can Coherence be my savior? Any other stable alternate too. (Coherence is imposed on me by big guys, FYI)

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• implementing a Intelligent File Transfer Software in java over TCP/IP

  - by whyjava

  Hello I am working on a proposal where we have to implement a software which can move files between one source to destination.The overall goal of this project is to create intelligent file transfer.This software will have three components :- 1) Broker : Broker is the module that communicates with other brokers, monitors files, moves files, retrieves configurations from the Configuration Manager, supplies process information for the monitor, archives files, writes all process data to log files and escalates issues if necessary 2) Configuration Manager :Configuration Manager is a web-based application used to configure and deploy the configuration to all brokers. 3) Monitor : Monitor is a web-based application used to monitor each Broker in the environment. This project has to be built up in java and protocol for file transfer in tcp/ip. Client does not want to use FTP. File Transfer seems very easy, until there are several processes who are waiting to pick the file up automatically. Several problems arise: How can we guarantee the file is received at the destination? If a file isn’t received the first time, we should try it again (even after a restart or power breakdown) ? How does the receiver knows the file that is received is complete? How can we transfer multiple files synchronously? How can we protect the bandwidth, so file transfer isn’t blocking other processes? How does one interoperate between multiple OS platforms? What about authentication? How can we monitor het workflow? Auditing / logging Archiving Can you please provide answer to some of these? Thanks

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• Does anyone still believe in the Capability Maturity Model for Software?

  - by Ed Guiness

  Ten years ago when I first encountered the CMM for software I was, I suppose like many, struck by how accurately it seemed to describe the chaotic "level one" state of software development in many businesses, particularly with its reference to reliance on heroes. It also seemed to provide realistic guidance for an organisation to progress up the levels improving their processes. But while it seemed to provide a good model and realistic guidance for improvement, I never really witnessed an adherence to CMM having a significant positive impact on any organisation I have worked for, or with. I know of one large software consultancy that claims CMM level 5 - the highest level - when I can see first hand that their processes are as chaotic, and the quality of their software products as varied, as other, non-CMM businesses. So I'm wondering, has anyone seen a real, tangible benefit from adherence to process improvement according to CMM? And if you have seen improvement, do you think that the improvement was specifically attributable to CMM, or would an alternative approach (such as six-sigma) have been equally or more beneficial? Does anyone still believe? As an aside, for those who haven't yet seen it, check out this funny-because-its-true parody

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• Is there a better way to keep track of session variable creation/access throughout different pages?

  - by Brandon

  Here's what I am working on. At my website I have multiple processes with each one containing multiple steps. Now in one of the processes, there is an error checking routine executed before proceeding to the next step of that process. A session var is set indicating the error status and it will either redirect back to the referrer or display the next page's contents. Now this kind of functionality, I believe, is common throughout web development. The issue that is occurring is that session vars are left around and are not being cleaned up properly. At times this introduces undesired behavior. My website is growing and I find that I am requiring more and more session vars to keep track of different system and error states. So I was thinking about creating a kind of "session variable keeper" to keep track of session var usage. The idea is fairly simple. It will have the notion of a context (e.g. registration process) and allow access to a predefined set of session vars within that context. In addition, the var and context will be paired with an action to proceed to some form of event handling. So if you haven't noticed I'm new to web development. Any thoughts or comments on the idea that I am proposing would be greatly appreciated. The back-end is written in PHP/MySQL.

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