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  • Unlocking a mutex from a different thread (C++)

    - by dan
    I'm using the C++ boost::thread library, which in my case means I'm using pthreads. Officially, a mutex must be unlocked from the same thread which locks it, and I want the effect of being able to lock in one thread and then unlock in another. There are many ways to accomplish this. One possibility would be to write a new mutex class which allows this behavior. For example: class inter_thread_mutex{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } I should point out that the above code doesn't guarantee FIFO access, since if one thread calls lock() while another calls unlock(), this first thread may acquire the lock ahead of other threads which are waiting. (Come to think of it, the boost::thread documentation doesn't appear to make any explicit scheduling guarantees for either mutexes or condition variables). But let's just ignore that (and any other bugs) for now. My question is, if I decide to go this route, would I be able to use such a mutex as a model for the boost Lockable concept. For example, would anything go wrong if I use a boost::unique_lock< inter_thread_mutex for RAII-style access, and then pass this lock to boost::condition_variable_any.wait(), etc. On one hand I don't see why not. On the other hand, "I don't see why not" is usually a very bad way of determining whether something will work. The reason I ask is that if it turns out that I have to write wrapper classes for RAII locks and condition variables and whatever else, then I'd rather just find some other way to achieve the same effect.

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  • OCCI createEnvironment Blocks My Thread

    - by sahs
    Hello, I'm writing a multi-threaded application, where there is a main thread which distributes tasks to the worker threads. According to the task, a worker thread creates a connection, by using a global occi environment. When a worker thread completes its task, it closes the connection (I'm sure, there is no exception thrown while termination). My problem is that after a while(sometimes 5 mins, sometimes 5 hours) the threads cannot get connection from the environment, and they get blocked there. What can be the problem?

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  • Start a thread in a different process in Java

    - by kolm
    Hi there, is it possible to start a new thread in a different process in Java? I mean, I'm running a specific process and main thread, issuing ProcessBuilder for creating a new process. Before start() method is invoked, one must provide the command to be run in another process. Is it possible to start a new thread in newly created process? Thank you in advance for the reply. Best regards.

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  • Issue accessing class variable from thread.

    - by James
    Hello, The code below is meant to take an arraylist of product objects as an input, spun thread for each product(and add the product to the arraylist 'products'), check product image(product.imageURL) availability, remove the products without images(remove the product from the arraylist 'products'), and return an arraylist of products with image available. package com.catgen.thread; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import com.catgen.Product; import com.catgen.Utils; public class ProductFilterThread extends Thread{ private Product product; private List<Product> products = new ArrayList<Product>(); public ProductFilterThread(){ } public ProductFilterThread(Product product){ this.product = product; } public synchronized void addProduct(Product product){ System.out.println("Before add: "+getProducts().size()); getProducts().add(product); System.out.println("After add: "+getProducts().size()); } public synchronized void removeProduct(Product product){ System.out.println("Before rem: "+getProducts().size()); getProducts().remove(product); System.out.println("After rem: "+getProducts().size()); } public synchronized List<Product> getProducts(){ return this.products; } public synchronized void setProducts(List<Product> products){ this.products = products; } public void run(){ boolean imageExists = Utils.fileExists(this.product.ImageURL); if(!imageExists){ System.out.println(this.product.ImageURL); removeProduct(this.product); } } public List<Product> getProductsWithImageOnly(List<Product> products){ ProductFilterThread pft = null; try{ List<ProductFilterThread> threads = new ArrayList<ProductFilterThread>(); for(Product product: products){ pft = new ProductFilterThread(product); addProduct(product); pft.start(); threads.add(pft); } Iterator<ProductFilterThread> threadsIter = threads.iterator(); while(threadsIter.hasNext()){ ProductFilterThread thread = threadsIter.next(); thread.join(); } }catch(Exception e){ e.printStackTrace(); } System.out.println("Total returned products = "+getProducts().size()); return getProducts(); } } Calling statement: displayProducts = new ProductFilterThread().getProductsWithImageOnly(displayProducts); Here, when addProduct(product) is called from within getProductsWithImageOnly(), getProducts() returns the list of products, but that's not the case(no products are returned) when the method removeProduct() is called by a thread, because of which the products without images are never removed. As a result, all the products are returned by the module whether or not the contained products have images. What can be the problem here? Thanks in advance. James.

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  • Boost BGL thread safety

    - by Budzoli
    Hi! I'd like multiple threads to use the dijkstra_shortest_paths and astar_search functions of the BGL, and then read the property maps of the result vertices and edges. I'm wondering wether I should use mutexes to ensure thread-safety. So here are my questions: 1., Are the dijkstra_shortest_paths and astar_search functions of the Boost.Graph thread safe? 2., If I only try to read the property maps of the graph from multiple threads, do I need to worry about thread safety?

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  • how to send some data to the Thread module on python and google-map-engine

    - by zjm1126
    from google.appengine.ext import db class Log(db.Model): content = db.StringProperty(multiline=True) class MyThread(threading.Thread): def run(self,request): #logs_query = Log.all().order('-date') #logs = logs_query.fetch(3) log=Log() log.content=request.POST.get('content',None) log.put() def Log(request): thr = MyThread() thr.start(request) return HttpResponse('') error is : Exception in thread Thread-1: Traceback (most recent call last): File "D:\Python25\lib\threading.py", line 486, in __bootstrap_inner self.run() File "D:\zjm_code\helloworld\views.py", line 33, in run log.content=request.POST.get('content',None) NameError: global name 'request' is not defined

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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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  • 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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