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• Stopping looping thread in Java

  - by halfwarp

  I'm using a thread that is continuously reading from a queue. Something like: public void run() { Object obj; while(true) { synchronized(objectsQueue) { if(objectesQueue.isEmpty()) { try { objectesQueue.wait(); } catch (InterruptedException e) { e.printStackTrace(); } obj = objectesQueue.poll(); } } // Do something with the Object obj } } What is the best way to stop this thread? I see two options: 1 - Since Thread.stop() is deprecated, I can implement a stopThisThread() method that uses a n atomic check-condition variable. 2 - Send a Death Event object or something like that to the queue. When the thread fetches a death event it exists. I prefer the 1st way, however, I don't know when to call the stopThisThread() method, as something might be on it's way to the queue and the stop signal can arrive first (not desirable). Any suggestions?

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• IPhone SDK - Vibration triggered by Thread

  - by Steblo

  Hi, I'm currently working on an IPhone App that should make the phone vibrate if a special event occurs. The checks to trigger the alert is done in a thread. Unfortunately the phone won't vibrate if I call AudioServicesPlaySystemSound(kSystemSoundID_Vibrate); from inside the thread. (It works fine if I call this in my "viewDidAppear" method). I even tried to do a callback from inside the thead like this: inside Thread: [self performSelectorOnMainThread:@selector(doAlarm) withObject:nil waitUntilDone:true]; -(void)doAlarm { AudioServicesPlaySystemSound(kSystemSoundID_Vibrate); } which has the same result: No vibration on the phone. How do I make the phone vibrate from inside a thread ?? Thanks in advance

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• Thread pool stack security issue

  - by elmatador

  In a naive implementation of a thread pool, can a piece of code that is being executed read the data left by some previous code on the stack (if it was running on the same thread instance)? Also, are there any other inherent security issues connected to thread pools?

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• passing parameters to a thread

  - by assassin

  I want to pass a function that takes a parameter to the ThreadStart Constructor in C#. But, it seems that this is not possible, as I get a syntax error it I try to do something like this Thread t1 = new Thread(new Thread Start(func1(obj1)); where obj1 is an object of type List<string> (say). If I want a thread to execute this function that takes in an object as a parameter, and I plan to create 2 such threads simultaneously with different parameter values what is the best method to achieve this?

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• Java - Thread - Problem in one of the Sun's tutorial

  - by Yatendra Goel

  I was reading this Sun's tutorial on Thread. I found a block of code there which I think can be replaced by a code of fewer lines. I wonder why Sun's expert programmers followed that long way when the task can be accomplished with a code of fewer lines. I am asking this question so as to know that if I am missing something that the tutorial wants to convey. The block of code is as follows: t.start(); threadMessage("Waiting for MessageLoop thread to finish"); //loop until MessageLoop thread exits while (t.isAlive()) { threadMessage("Still waiting..."); //Wait maximum of 1 second for MessageLoop thread to //finish. t.join(1000); if (((System.currentTimeMillis() - startTime) > patience) && t.isAlive()) { threadMessage("Tired of waiting!"); t.interrupt(); //Shouldn't be long now -- wait indefinitely t.join(); } } threadMessage("Finally!"); I think that the above code can be replaced by the following: t.start(); t.join(patience); // InterruptedException is thrown by the main method so no need to handle it if(t.isAlive()) { // t's thread couldn't finish in the patience time threadMessage("Tired of waiting!"); t.interrupt(); t.join(); } threadMessage("Finally!");

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• C# Basic Multi-Threading Question: Call Method on Thread A from Thread B (Thread B started from Thre

  - by Nick

  What is the best way to accomplish this: The main thread (Thread A) creates two other threads (Thread B and Thread C). Threads B and C do heavy disk I/O and eventually need to pass in resources they created to Thread A to then call a method in an external DLL file which requires the thread that created it to be called correctly so only Thread A can call it. The only other time I ever used threads was in a Windows Forms application, and the invoke methods were just what I needed. This program does not use Windows Forms, and as such there are no Control.Invoke methods to use. I have noticed in my testing that if a variable is created in Thread A, I have no trouble accessing and modifying it from Thread B/C which seems very wrong to me. With Winforms, I was sure it threw errors for trying to access things created on other threads. I know it is unsafe to change things from multiple threads, but I really hoped .NET would forbid it altogether to ensure safe coding. Does .NET do this, and I am just missing the boat, or does it only do it with WinForm apps? Since it does seemingly allow this, do I do something like an OS would do, create a flag and monitor it from Thread A to see if it changes. If it does, then call the method. Doesnt the event handler essentially do this, so could an event be used somehow called on the main thread?

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• Race condition for thread startup

  - by Ozzah

  A similar question was asked here, but the answers generally all seem to relate to the lambda notation. I get a similar result without the lambda so I thought I'd ask for some clarification: Say I have something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); One would expect the following output: Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Now I realise that the threads aren't started in any particular order, so let's just assume that the above lines can come out in any order. But that is not what happens. What instead happens: Thread 3 Thread 4 Thread 4 Thread 4 Thread 4 or something similar, which leads me to believe that rather than passing the value if i, it is passing the reference. (Which is weird, since an int is a value type). Doing something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { int j = i; Console.WriteLine("Thread " + j); }))).Start(); does not help either, even though we have made a copy of i. I am assuming the reason is that it hasn't made a copy of i in time. Doing something like this: for (int i = 0; i < 5; i++) { (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); Thread.Sleep(50); } seems to fix the problem, however it is extremely undesirable as we're wasting 50ms on each iteration, not to mention the fact that if the computer is heavily loaded then maybe 50ms may not be enough. Here is a sample with my current, specific problem: Thread t = new Thread(new ThreadStart(delgate() { threadLogic(param1, param2, param3, param4); })); t.Start(); param1 = param2 = param3 = param4 = null; with: void threadLogic(object param1, object param2, object param3, object param4) { // Do some stuff here... } I want threadLogic() to run in its own thread, however the above code gives a null reference exception. I assume this is because the values are set to null before the thread has had a chance to start. Again, putting a Thread.Sleep(100) works, but it is an awful solution from every aspect. What do you guys recommend for this particular type of race condition?

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• Update ListView in the main thread from another thread

  - by Wilson

  I have a separate thread running to get data from the internet. After that, I would like to update the ListView in the main thread by calling adapter.notifyDataSetChanged(). But it does not work. Any workaround for that? Thanks.

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• How to Use RDA to Generate WLS Thread Dumps At Specified Intervals?

  - by Daniel Mortimer

  Introduction There are many ways to generate a thread dump of a WebLogic Managed Server. For example, take a look at: Taking Thread Dumps - [an excellent blog post on the Middleware Magic site]or  Different ways to take thread dumps in WebLogic Server (Document 1098691.1) There is another method - use Remote Diagnostic Agent! The solution described below is not documented, but it is relatively straightforward to execute. One advantage of using RDA to collect the thread dumps is RDA will also collect configuration, log files, network, system, performance information at the same time. Instructions 1. Not familiar with Remote Diagnostic Agent? Take a look at my previous blog "Resolve SRs Faster Using RDA - Find the Right Profile" 2. Choose a profile, which includes the WebLogic Server data collection modules (for example the profile "WebLogicServer"). At RDA setup time you should see the prompt below: ------------------------------------------------------------------------------- S301WLS: Collects Oracle WebLogic Server Information ------------------------------------------------------------------------------- Enter the location of the directory where the domains to analyze are located (For example in UNIX, <BEA Home>/user_projects/domains or <Middleware Home>/user_projects/domains) Hit 'Return' to accept the default (/oracle/11AS/Middleware/user_projects/domains) > For a successful WLS connection, ensure that the domain Admin Server is up and running. Data Collection Type:   1  Collect for a single server (offline mode)   2  Collect for a single server (using WLS connection)   3  Collect for multiple servers (using WLS connection) Enter the item number Hit 'Return' to accept the default (1) > 2 Choose option 2 or 3. Note: Collect for a single server or multiple servers using WLS connection means that RDA will attempt to connect to execute online WLST commands against the targeted server(s). The thread dumps are collected using the WLST function - "threadDumps()". If WLST cannot connect to the managed server, RDA will proceed to collect other data and ignore the request to collect thread dumps. If in the final output you see no Thread Dump menu item, then it's likely that the managed server is in a state which prevents new connections to it. If faced with this scenario, you would have to employ alternative methods for collecting thread dumps. 3. The RDA setup will create a setup.cfg file in the RDA_HOME directory. Open this file in an editor. You will find the following parameters which govern the number of thread dumps and thread dump interval. #N.Number of thread dumps to capture WREQ_THREAD_DUMP=10 #N.Thread dump interval WREQ_THREAD_DUMP_INTERVAL=5000 The example lines above show the default settings. In other words, RDA will collect 10 thread dumps at 5000 millisecond (5 second) intervals. You may want to change this to something like: #N.Number of thread dumps to capture WREQ_THREAD_DUMP=10 #N.Thread dump interval WREQ_THREAD_DUMP_INTERVAL=30000 However, bear in mind, that such change will increase the total amount of time it takes for RDA to complete its run. 4. Once you are happy with the setup.cfg, run RDA. RDA will collect, render, generate and package all files in the output directory. 5. For ease of viewing, open up the RDA Start html file - "xxxx__start.htm". The thread dumps can be found under the WLST Collections for the target managed server(s). See screenshots belowScreenshot 1:RDA Start Page - Main Index Screenshot 2: Managed Server Sub Index Screenshot 3: WLST Collections Screenshot 4: Thread Dump Page - List of dump file links Screenshot 5: Thread Dump Dat File Link Additional Comment: A) You can view the thread dump files within the RDA Start Page framework, but most likely you will want to download the dat files for in-depth analysis via thread dump analysis tools such as: Thread Dump Analyzer -  Samurai - a GUI based tail , thread dump analysis tool If you are new to thread dump analysis - take a look at this recorded Support Advisor Webcast  Oracle WebLogic Server: Diagnosing Performance Issues through Java Thread Dumps[Slidedeck from webcast in PDF format]B) I have logged a couple of enhancement requests for the RDA Development Team to consider: Add timestamp to dump file links, dat filename and at the top of the body of the dat file Package the individual thread dumps in a zip so all dump files can be conveniently downloaded in one go.

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• Spring transaction : Transaction not active

  - by Videanu Adrian

  i develop a app using struts2, spring 3.1, Jpa2 and Hibernate. From Spring i use transactions and IoC. so, i have an ajax code block that calls for a struts2 action every second (this is happening for every user that is logged into application (simultaneous users are around 20-30 at a time)). this action name is PopupAction public class PopupAction extends VActionBase implements ServletRequestAware { private static final long serialVersionUID = -293004532677112584L; private iIntermedService intermedService; private HttpServletRequest servletRequest; @Override public String execute() { Integer agentId = (Integer) session.get("USER_AGENT_ID"); Intermed iObj; try { iObj = intermedService.getIntermed(agentId,locationsString); } catch (Exception e) { logger.error("Cannot get Intermed!!! "+e.getMessage()); return ERROR; } return SUCCESS; } } and then i have the service class : @Transactional(readOnly=true) public class IntermedServiceImpl extends GenericIService<Intermed, Integer> implements iIntermedService { @Override public Intermed getIntermed (int agentId,String queueIds) throws Exception { Intermed intermedObj = null; //TODO - find a better implementation for this queueIds parameter!!!! try{ String sql = "SELECT i FROM bla bla bla.....)"; Query q = this.em.createQuery(sql); List<Intermed> iList = q.getResultList(); if (iList.size() == 1){ intermedObj = (Intermed) iList.get(0); //get latest object from DB em.refresh(intermedObj); } }catch(Exception e){ e.printStackTrace(); logger.error(e.getCause()+e.getMessage()); throw e; } return intermedObj; } } here is the spring configuration : <bean id="emfI" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="inboundDS" /> <property name="persistenceUnitName" value="I2PU"/> <!-- GlassFish load-time weaving setup --> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.glassfish.GlassFishLoadTimeWeaver"/> </property> </bean> <tx:annotation-driven transaction-manager="txManagerI" /> <tx:advice id="txManagerInboundAdvice" transaction-manager="txManagerI"> <tx:attributes> <tx:method name="*" rollback-for="java.lang.Exception"/> </tx:attributes> </tx:advice> I have names for transactionManager because i have 3 datasources and 3 transaction managers. the problem is that my glassfish logs are full of messages like these: -- removed in order to be able to add more recent logs -- So the cause is : Caused by: java.lang.IllegalStateException: Transaction not active. But i have no idea what can cause this. Any help ? thanks Updates So i have added to @Transactional annotation the transaction manager name that he has to use, but this still does not solved my problem. I have captured a log from the time that the transaction is created until i got that exception: 2012-02-08T15:08:55.954+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractBeanFactory.java:245) - Returning cached instance of singleton bean 'txManagerVA' 2012-02-08T15:08:55.962+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:365) - Creating new transaction with name [xxx.vs.common.services.inbound.IntermedServiceImpl.getIntermed]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly; '',-java.lang.Exception 2012-02-08T15:08:55.967+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (JpaTransactionManager.java:368) - Opened new EntityManager [org.hibernate.ejb.EntityManagerImpl@edf83f9] for JPA transaction 2012-02-08T15:08:55.976+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (JpaTransactionManager.java:400) - Exposing JPA transaction as JDBC transaction [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@725b979b] 2012-02-08T15:08:55.977+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:193) - Bound value [org.springframework.jdbc.datasource.ConnectionHolder@4fb57177] for key [com.sun.gjc.spi.jdbc40.DataSource40@75fa4851] to thread [thread-pool-1-80(80)] 2012-02-08T15:08:55.978+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:193) - Bound value [org.springframework.orm.jpa.EntityManagerHolder@112c6483] for key [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean@47d4f12f] to thread [thread-pool-1-80(80)] 2012-02-08T15:08:55.979+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:272) - Initializing transaction synchronization 2012-02-08T15:08:55.980+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionAspectSupport.java:362) - Getting transaction for [xxx.vs.common.services.inbound.IntermedServiceImpl.getIntermed] 2012-02-08T15:08:55.983+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (ExtendedEntityManagerCreator.java:423) - Starting resource local transaction on application-managed EntityManager [org.hibernate.ejb.EntityManagerImpl@46d002f4] 2012-02-08T15:08:55.984+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:193) - Bound value [org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerSynchronization@797add43] for key [org.hibernate.ejb.EntityManagerImpl@46d002f4] to thread [thread-pool-1-80(80)] 2012-02-08T15:08:55.986+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (ExtendedEntityManagerCreator.java:400) - Joined local transaction 2012-02-08T15:08:55.991+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionAspectSupport.java:391) - Completing transaction for [xxx.vs.common.services.inbound.IntermedServiceImpl.getIntermed] 2012-02-08T15:08:55.992+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:922) - Triggering beforeCommit synchronization 2012-02-08T15:08:55.994+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:935) - Triggering beforeCompletion synchronization 2012-02-08T15:08:56.001+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:243) - Removed value [org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerSynchronization@797add43] for key [org.hibernate.ejb.EntityManagerImpl@46d002f4] from thread [thread-pool-1-80(80)] 2012-02-08T15:08:56.002+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:752) - Initiating transaction commit 2012-02-08T15:08:56.003+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (JpaTransactionManager.java:507) - Committing JPA transaction on EntityManager [org.hibernate.ejb.EntityManagerImpl@edf83f9] 2012-02-08T15:08:56.008+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:948) - Triggering afterCommit synchronization 2012-02-08T15:08:56.010+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (AbstractPlatformTransactionManager.java:964) - Triggering afterCompletion synchronization 2012-02-08T15:08:56.011+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:331) - Clearing transaction synchronization 2012-02-08T15:08:56.012+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:243) - Removed value [org.springframework.orm.jpa.EntityManagerHolder@112c6483] for key [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean@47d4f12f] from thread [thread-pool-1-80(80)] 2012-02-08T15:08:56.021+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (TransactionSynchronizationManager.java:243) - Removed value [org.springframework.jdbc.datasource.ConnectionHolder@4fb57177] for key [com.sun.gjc.spi.jdbc40.DataSource40@75fa4851] from thread [thread-pool-1-80(80)] 2012-02-08T15:08:56.021+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (JpaTransactionManager.java:593) - Closing JPA EntityManager [org.hibernate.ejb.EntityManagerImpl@edf83f9] after transaction 2012-02-08T15:08:56.022+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|DEBUG [thread-pool-1-80(80)] (EntityManagerFactoryUtils.java:343) - Closing JPA EntityManager 2012-02-08T15:08:56.023+0200|INFO||_ThreadID=184;_ThreadName=Thread-5;|ERROR [thread-pool-1-80(80)] (PopupAction.java:39) - Cannot get Intermed!!! Transaction not active; nested exception is java.lang.IllegalStateException: Transaction not active 2012-02-08T15:08:56.024+0200|SEVERE||_ThreadID=184;_ThreadName=Thread-5;|org.springframework.dao.InvalidDataAccessApiUsageException: Transaction not active; nested exception is java.lang.IllegalStateException: Transaction not active at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:298) at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:106) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerSynchronization.convertException(ExtendedEntityManagerCreator.java:501) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerSynchronization.afterCommit(ExtendedEntityManagerCreator.java:481) at org.springframework.transaction.support.TransactionSynchronizationUtils.invokeAfterCommit(TransactionSynchronizationUtils.java:133) at org.springframework.transaction.support.TransactionSynchronizationUtils.triggerAfterCommit(TransactionSynchronizationUtils.java:121) at org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerAfterCommit(AbstractPlatformTransactionManager.java:950) at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:796) at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:723) at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:393) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:120) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) at $Proxy325.getIntermed(Unknown Source) at xxx.vs.common.actions.PopupAction.execute(PopupAction.java:37) at sun.reflect.GeneratedMethodAccessor1581.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255) at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at xxx.vs.common.utils.AuthenticationInterceptor.intercept(AuthenticationInterceptor.java:78) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at com.googlecode.sslplugin.interceptors.SSLInterceptor.intercept(SSLInterceptor.java:128) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54) at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:510) at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91) at org.apache.catalina 2012-02-08T15:08:56.024+0200|SEVERE||_ThreadID=184;_ThreadName=Thread-5;|.core.StandardHostValve.invoke(StandardHostValve.java:162) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59) at com.sun.grizzly.ContextTask.run(ContextTask.java:71) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513) at java.lang.Thread.run(Thread.java:679) Caused by: java.lang.IllegalStateException: Transaction not active at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:69) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerSynchronization.afterCommit(ExtendedEntityManagerCreator.java:478) ... 93 more so again..... any ideea ?

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• Web image loaded by thread in android

  - by Bostjan

  I have an extended BaseAdapter in a ListActivity: private static class RequestAdapter extends BaseAdapter { and some handlers and runnables defined in it // Need handler for callbacks to the UI thread final Handler mHandler = new Handler(); // Create runnable for posting final Runnable mUpdateResults = new Runnable() { public void run() { loadAvatar(); } }; protected static void loadAvatar() { // TODO Auto-generated method stub //ava.setImageBitmap(getImageBitmap("URL"+pic)); buddyIcon.setImageBitmap(avatar); } In the getView function of the Adapter, I'm getting the view like this: if (convertView == null) { convertView = mInflater.inflate(R.layout.messageitem, null); // Creates a ViewHolder and store references to the two children views // we want to bind data to. holder = new ViewHolder(); holder.username = (TextView) convertView.findViewById(R.id.username); holder.date = (TextView) convertView.findViewById(R.id.dateValue); holder.time = (TextView) convertView.findViewById(R.id.timeValue); holder.notType = (TextView) convertView.findViewById(R.id.notType); holder.newMsg = (ImageView) convertView.findViewById(R.id.newMsg); holder.realUsername = (TextView) convertView.findViewById(R.id.realUsername); holder.replied = (ImageView) convertView.findViewById(R.id.replied); holder.msgID = (TextView) convertView.findViewById(R.id.msgID_fr); holder.avatar = (ImageView) convertView.findViewById(R.id.buddyIcon); holder.msgPreview = (TextView) convertView.findViewById(R.id.msgPreview); convertView.setTag(holder); } else { // Get the ViewHolder back to get fast access to the TextView // and the ImageView. holder = (ViewHolder) convertView.getTag(); } and the image is getting loaded this way: Thread sepThread = new Thread() { public void run() { String ava; ava = request[8].replace(".", "_micro."); Log.e("ava thread",ava+", username: "+request[0]); avatar = getImageBitmap(URL+ava); buddyIcon = holder.avatar; mHandler.post(mUpdateResults); //holder.avatar.setImageBitmap(getImageBitmap(URL+ava)); } }; sepThread.start(); Now, the problem I'm having is that if there are more items that need to display the same picture, not all of those pictures get displayed. When you scroll up and down the list maybe you end up filling all of them. When I tried the commented out line (holder.avatar.setImageBitmap...) the app sometimes force closes with "only the thread that created the view can request...". But only sometimes. Any idea how I can fix this? Either option.

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• Linker Issues with boost::thread under linux using Eclipse and CMake

  - by OcularProgrammer

  I'm in the process of attempting to port some code across from PC to Ubuntu, and am having some issues due to limited experience developing under linux. We use CMake to generate all our build stuff. Under windows I'm making VS2010 projects, and under Linux I'm making Eclipse projects. I've managed to get my OpenCV stuff ported across successfully, but am having major headaches trying to port my threaded boost apps. Just so we're clear, the steps I have followed so-far on a clean Ubuntu 12 installation. (I've done 2 clean re-installs to try and fix potential library cock-ups, now I'm just giving up and asking): Install Eclipse and Eclipse CDT using my package manager Install CMake and CMake Gui using my package manager Install libboost-all-dev using my package manager So-far that's all I've done. I can create the eclipse project using CMake with no errors, so CMake is successfully finding my boost install. When I try and build through eclipse is when I get issues; The app I'm attempting to build uses boost::asio for some UDP I/O and boost::thread to create worker threads for the asio I/O services. I can successfully compile each module, but when I come to link I get spammed with errors such as: /usr/bin/c++ CMakeFiles/RE05DevelopmentDemo.dir/main.cpp.o CMakeFiles/RE05DevelopmentDemo.dir/RE05FusionListener/RE05FusionListener.cpp.o CMakeFiles/RE05DevelopmentDemo.dir/NewEye/NewEye.cpp.o -o RE05DevelopmentDemo -rdynamic -Wl,-Bstatic -lboost_system-mt -lboost_date_time-mt -lboost_regex-mt -lboost_thread-mt -Wl,-Bdynamic /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) [clone .constprop.98]': make[2]: Leaving directory `/home/david/Code/Build/Support/RE05DevDemo' (.text+0xc8): undefined reference to `pthread_key_create' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::interruption_enabled()': (.text+0x540): undefined reference to `pthread_getspecific' make[1]: Leaving directory `/home/david/Code/Build/Support/RE05DevDemo' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::disable_interruption::disable_interruption()': (.text+0x570): undefined reference to `pthread_getspecific' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::disable_interruption::disable_interruption()': (.text+0x59f): undefined reference to `pthread_getspecific' Some Gotchas that I have collected from other StackOverflow posts and have already checked: The boost libs are all present at /usr/lib I am not getting any compile errors for inability to find the boost headers, so they must be getting found. I am trying to link statically, but I believe eclipse should be passing the correct arguments to make that happen since my CMakeLists.txt includes SET(Boost_USE_STATIC_LIBS ON) I'm officially out of ideas here, I have tried doing local builds of boost and a bunch of other stuff with no more success. I even re-installed Ubuntu to ensure I haven't completely fracked the libs directories and links with multiple weird versions or anything else. Any help would be muchly appreciated.

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• android shut-down errors / thread problems

  - by iQue

  Im starting to deal with some stuff in my game that I thought were "minor problems" and one of these are that I get an error every time I shut down my game that looks like this: 09-05 21:40:58.320: E/AndroidRuntime(30401): FATAL EXCEPTION: Thread-4898 09-05 21:40:58.320: E/AndroidRuntime(30401): java.lang.NullPointerException 09-05 21:40:58.320: E/AndroidRuntime(30401): at nielsen.happy.shooter.MainGamePanel.render(MainGamePanel.java:94) 09-05 21:40:58.320: E/AndroidRuntime(30401): at nielsen.happy.shooter.MainThread.run(MainThread.java:101) on these lines is my GameViews rendering-method and the line in my Thread that calls my GameViews rendering-method. Im guessing Something in my surfaceDestroyed(SurfaceHolder holder) is wrong, or maybe Im not ending the tread in the right place. My surfaceDestroyed-method: public void surfaceDestroyed(SurfaceHolder holder) { Log.d(TAG, "Surface is being destroyed"); boolean retry = true; ((MainThread)thread).setRunning(false); while (retry) { try { ((MainThread)thread).join(); retry = false; } catch (InterruptedException e) { } } Log.d(TAG, "Thread was shut down cleanly"); } Also, In my activity for this View my onPaus, onDestoy and onStop are empty, do I maybe need to add something there? The crash occurs when I press my home-button on the phone, or any other button that makes the game stop. But as I understand it the onPaus is called when you press the Home-button.. This is really new territory for me so Im sorry if im missing something obvious or something really big. adding my surfaceCreated method asweel since that is where I start this thread: public void surfaceCreated(SurfaceHolder holder) { controls = new GameControls(this); setOnTouchListener(controls); timer1.schedule(new Task(this), 0, delay1); thread.setRunning(true); thread.start(); } and aslong as this is running, my game is rendering and updating.

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• Java Stop Server Thread

  - by ikurtz

  the following code is server code in my app: private int serverPort; private Thread serverThread = null; public void networkListen(int port){ serverPort = port; if (serverThread == null){ Runnable serverRunnable = new ServerRunnable(); serverThread = new Thread(serverRunnable); serverThread.start(); } else { } } public class ServerRunnable implements Runnable { public void run(){ try { //networkConnected = false; //netMessage = "Listening for Connection"; //networkMessage = new NetworkMessage(networkConnected, netMessage); //setChanged(); //notifyObservers(networkMessage); ServerSocket serverSocket = new ServerSocket(serverPort, backlog); commSocket = serverSocket.accept(); serverSocket.close(); serverSocket = null; //networkConnected = true; //netMessage = "Connected: " + commSocket.getInetAddress().getHostAddress() + ":" + //commSocket.getPort(); //networkMessage = new NetworkMessage(networkConnected, netMessage); //setChanged(); //notifyObservers(networkMessage); } catch (IOException e){ //networkConnected = false; //netMessage = "ServerRunnable Network Unavailable"; //System.out.println(e.getMessage()); //networkMessage = new NetworkMessage(networkConnected, netMessage); //setChanged(); //notifyObservers(networkMessage); } } } The code sort of works i.e. if im attempting a straight connection both ends communicate and update. The issue is while im listening for a connection if i want to quit listening then the server thread continues running and causes problems. i know i should not use .stop() on a thread so i was wondering what the solution would look like with this in mind? EDIT: commented out unneeded code.

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• Thread-local storage segfaults on NetBSD only?

  - by bortzmeyer

  Trying to run a C++ program, I get segmentation faults which appear to be specific to NetBSD. Bert Hubert wrote the simple test program (at the end of this message) and, indeed, it crashes only on NetBSD. % uname -a NetBSD golgoth 5.0.1 NetBSD 5.0.1 (GENERIC) #0: Thu Oct 1 15:46:16 CEST 2009 +stephane@golgoth:/usr/obj/sys/arch/i386/compile/GENERIC i386 % g++ --version g++ (GCC) 4.1.3 20080704 prerelease (NetBSD nb2 20081120) Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. % gdb thread-local-storage-powerdns GNU gdb 6.5 Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386--netbsdelf"... (gdb) run Starting program: /home/stephane/Programmation/C++/essais/thread-local-storage-powerdns Program received signal SIGSEGV, Segmentation fault. 0x0804881b in main () at thread-local-storage-powerdns.cc:20 20 t_a = new Bogo('a'); (gdb) On other Unix, it works fine. Is there a known issue in NetBSD with C++ thread-local storage? #include <stdio.h> class Bogo { public: explicit Bogo(char a) { d_a = a; } char d_a; }; __thread Bogo* t_a; int main() { t_a = new Bogo('a'); Bogo* b = t_a; printf("%c\n", b->d_a); }

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• Return Double from Boost thread

  - by Benedikt Wutzi

  Hi I have an Boost thread which should return a double. The function looks like this: void analyser::findup(const double startwl, const double max, double &myret){ this->data.begin(); for(int i = (int)data.size() ; i >= 0;i--){ if(this->data[i].lambda > startwl){ if(this->data[i].db >= (max-30)) { myret = this->data[i+1].lambda; std::cout <<"in thread " << myret << std::endl; return; } } } } this function is called by another function: void analyser::start_find_up(const double startwl, const double max){ double tmp = -42.0; boost::thread up(&analyser::findup,*this, startwl,max,tmp); std::cout << "before join " << tmp << std::endl; up.join(); std::cout << "after join " << tmp << std::endl; } Anyway I've tried and googled almost anything but i can't get it to return a value. The output looks like this right now. before join -42 in thread 843.487 after join -42 Thanks for any help.

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• Thread-safety of read-only memory access

  - by Edmund

  I've implemented the Barnes-Hut gravity algorithm in C as follows: Build a tree of clustered stars. For each star, traverse the tree and apply the gravitational forces from each applicable node. Update the star velocities and positions. Stage 2 is the most expensive stage, and so is implemented in parallel by dividing the set of stars. E.g. with 1000 stars and 2 threads, I have one thread processing the first 500 stars and the second thread processing the second 500. In practice this works: it speeds the computation by about 30% with two threads on a two-core machine, compared to the non-threaded version. Additionally, it yields the same numerical results as the original non-threaded version. My concern is that the two threads are accessing the same resource (namely, the tree) simultaneously. I have not added any synchronisation to the thread workers, so it's likely they will attempt to read from the same location at some point. Although access to the tree is strictly read-only I am not 100% sure it's safe. It has worked when I've tested it but I know this is no guarantee of correctness! Questions Do I need to make a private copy of the tree for each thread? Even if it is safe, are there performance problems of accessing the same memory from multiple threads?

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• Passing variables from a thread to another form using C#

  - by kirstom14

  Hi, I am trying to pass 2 variables from a thread, in the MainForm, to another form, but when doing so an error occurs. private void TrackingThread( ) { float targetX = 0; float targetY = 0; while ( true ) { camera1Acquired.WaitOne( ); camera2Acquired.WaitOne( ); lock ( this ) { // stop the thread if it was signaled if ( ( x1 == -1 ) && ( y1 == -1 ) && ( x2 == -1 ) && ( y2 == -1 ) ) { break; } // get middle point targetX = ( x1 + x2 ) / 2; targetY = ( y1 + y2 ) / 2; } if (directionForm != null) { directionForm.RunMotors(targetX, targetY); } } } In the form, directionForm, I am simply displaying the variables targetX and targetY. The code for the directionForm.RunMotors() is the following: public void RunMotors(float x, float y) { label1.Text = "X-ordinate " + x.ToString(); label2.Text = "Y-ordinate " + y.ToString(); } The error happen when I am trying to display the two variables: "InvalidOperationException was unhandled Cross-threading operation not valid: Control label1 accessed from a thread other than . the thread it was created on" What shall I do??? Thanks in advance

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• Need a Java based interruptible timer thread

  - by LambeauLeap

  I have a Main Program which is running a script on the target device(smart phone) and in a while loop waiting for stdout messages. However in this particular case, some of the heartbeat messages on the stdout could be spaced almost 45secs to a 1minute apart. something like: stream = device.runProgram(RESTORE_LOGS, new String[] {}); stream.flush(); String line = stream.readLine(); while (line.compareTo("") != 0) { reporter.commentOnJob(jobId, line); line = stream.readLine(); } So, I want to be a able to start a new interruptible thread after reading line from stdout with a required a sleep window. Upon being able to read a new line, I want to be able to interrupt/stop(having trouble killing the process), handle the newline of stdout text and restart a process. And it the event I am not able to read a line within the timer window(say 45secs) I want to a way to get out of my while loop either. I already tried the thread.run, thread.interrupt approach. But having trouble killing and starting a new thread. Is this the best way out or am I missing something obvious?

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• .NET List Thread-Safe Implementation Suggestion needed

  - by Bamboo

  .Net List class isn't thread safe. I hope to achieve the minimal lock needed and yet still fulfilling the requirement such that as for reading, phantom record is allowed, and for writing, they must be thread-safe so there won't be any lost updates. So I have something like public static List<string> list = new List<string>(); In Methods that have **List.Add**/**List.Remove** , I always lock to assure thread safety lock (lockHelper) { list.Add(obj); or list.Remove(obj); } In Methods that requires **List Reading** I don't care about phantom record so I go ahead to read without any locking. In this case. Return a bool by checking whether a string had been added. if (list.Count() != 0) { return list.Contains("some string") } All I did was locking write accesses, and allow read accesses to go through without any locking. Is my thread safety idea valid? I understand there is List size expansion. Will it be ok? My guess is that when a List is expanding, it may uses a temp. list. This is ok becasue the temp list size will always have a boundary, and .Net class is well implemented, ie. there shouldn't be any indexOutOfBound or circular reference problems when reading was caught in updates.

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• Syncronization Exception

  - by Kurru

  Hi I have two threads, one thread processes a queue and the other thread adds stuff into the queue. I want to put the queue processing thread to sleep when its finished processing the queue I want to have the 2nd thread tell it to wake up when it has added an item to the queue However these functions call System.Threading.SynchronizationLockException: Object synchronization method was called from an unsynchronized block of code on the Monitor.PulseAll(waiting); call, because I havent syncronized the function with the waiting object. [which I dont want to do, i want to be able to process while adding items to the queue]. How can I achieve this? Queue<object> items = new Queue<object>(); object waiting = new object(); 1st Thread public void ProcessQueue() { while (true) { if (items.Count == 0) Monitor.Wait(waiting); object real = null; lock(items) { object item = items.Dequeue(); real = item; } if(real == null) continue; .. bla bla bla } } 2nd Thread involves public void AddItem(object o) { ... bla bla bla lock(items) { items.Enqueue(o); } Monitor.PulseAll(waiting); }

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• .NET SerialPort DataReceived event thread interference with main thread

  - by Kiran

  I am writing a serial communication program using the SerialPort class in C# to interact with a strip machine connected via a RS232 cable. When i send the command to the machine it responds with some bytes depending on the command. Like when i send a "\D" command, i am expecting to download the machine program data of 180 bytes as a continous string. As per the machine's manual, it suggests as a best practice to send an unreognized characters like comma (,) character to make sure the machine is initialized before sending the first command in the cycle. My serial communication code is as follows: public class SerialHelper { SerialPort commPort = null; string currentReceived = string.Empty; string receivedStr = string.Empty; private bool CommInitialized() { try { commPort = new SerialPort(); commPort.PortName = "COM1"; if (!commPort.IsOpen) commPort.Open(); commPort.BaudRate = 9600; commPort.Parity = System.IO.Ports.Parity.None; commPort.StopBits = StopBits.One; commPort.DataBits = 8; commPort.RtsEnable = true; commPort.DtrEnable = true; commPort.DataReceived += new SerialDataReceivedEventHandler(commPort_DataReceived); return true; } catch (Exception ex) { return false; } } void commPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { SerialPort currentPort = (SerialPort)sender; currentReceived = currentPort.ReadExisting(); receivedStr += currentReceived; } internal int CommIO(string outString, int outLen, ref string inBuffer, int inLen) { receivedStr = string.Empty; inBuffer = string.Empty; if (CommInitialized()) { commPort.Write(outString); } System.Threading.Thread.Sleep(1500); int i = 0; while ((receivedStr.Length < inLen) && i < 10) { System.Threading.Thread.Sleep(500); i += 1; } if (!string.IsNullOrEmpty(receivedStr)) { inBuffer = receivedStr; } commPort.Close(); return inBuffer.Length; } } I am calling this code from a windows form as follows: len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) If(inBuffer == "!?*O") { len = SerialHelperObj.CommIO("\D",2,ref inBuffer, 180) } A valid return value from the serial port looks like this: \D00000010000000000010 550 3250 0000256000 and so on ... I am getting some thing like this: \D00000010D,, 000 550 D,, and so on... I feel that my comm calls are getting interferred with the one when i send commands. But i am trying to make sure the result of the comma command then initiating the actual command. but the received thread is inserting the bytes from the previous communication cycle. Can any one please shed some light into this...? I lost quite some hair just trying to get this work. I am not sure where i am doing wrong

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• .NET Thread Pool - Unresponsive WinForms UI

  - by Goober

  Scenario I have a Windows Forms Application. Inside the main form there is a loop that iterates around 3000 times, Creating a new instance of a class on a new thread to perform some calculations. Bearing in mind that this setup uses a Thread Pool, the UI does stay responsive when there are only around 100 iterations of this loop (100 Assets to process). But as soon as this number begins to increase heavily, the UI locks up into eggtimer mode and the thus the log that is writing out to the listbox on the form becomes unreadable. Question Am I right in thinking that the best way around this is to use a Background Worker? And is the UI locking up because even though I'm using lots of different threads (for speed), the UI itself is not on its own separate thread? Suggested Implementations greatly appreciated.

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• C# Win Forms Thread Pool - Unresponsive UI

  - by Goober

  Scenario I have a Windows Form Application. Inside the main form there is a loop that iterates around 3000 times, Creating a new instance of a class on a new thread to perform some calculations. Baring in mind that this setup uses a Thread Pool, the UI does stay responsive when there are only around 100 iterations of this loop (100 Assets to process). But as soon as this number begins to increase heavily, the UI locks up into eggtimer mode and the thus the log that is writing out to the listbox on the form becomes unreadable. Question Am I right in thinking that the best way around this is to use a Background Worker? And is the UI locking up because even though I'm using lots of different threads (for speed), the UI itself is not on its own separate thread? Suggested Implementations greatly appreciated.

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• python urllib2 thread safety

  - by jldupont

  Is urllib2 thread safe? I find that using urllib2.urlopen sometimes results in the thread issuing the call to stop functioning. Yes I have used the timeout option to no avail. Is there a thread safe HTTP GET functionality I could use? NOTE: I am not interested in using Twisted to solve this problem. I have used Twisted in the past and I love it but this time I need a simpler solution. NOTE2: I also tried httplib with the same result (blocking).

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