Hi,

I'm working on some application and using ThreadPoolExecutor for handling various tasks. ThreadPoolExecutor is getting stuck after some duration. To simulate this in a simpler environment, I've written a simple code where I'm able to simulate the issue.

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class MyThreadPoolExecutor {
    private int poolSize = 10;
    private int maxPoolSize = 50;
    private long keepAliveTime = 10;
    private ThreadPoolExecutor threadPool = null;
    private final ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(
            100000);

    public MyThreadPoolExecutor() {
        threadPool = new ThreadPoolExecutor(poolSize, maxPoolSize,
                keepAliveTime, TimeUnit.SECONDS, queue);
        threadPool.setRejectedExecutionHandler(new RejectedExecutionHandler() {

            @Override
            public void rejectedExecution(Runnable runnable,
                    ThreadPoolExecutor threadPoolExecutor) {
                System.out
                        .println("Execution rejected. Please try restarting the application.");
            }

        });
    }

    public void runTask(Runnable task) {
        threadPool.execute(task);
    }

    public void shutDown() {
        threadPool.shutdownNow();
    }
    public ThreadPoolExecutor getThreadPool() {
        return threadPool;
    }

    public void setThreadPool(ThreadPoolExecutor threadPool) {
        this.threadPool = threadPool;
    }

    public static void main(String[] args) {
        MyThreadPoolExecutor mtpe = new MyThreadPoolExecutor();
        for (int i = 0; i < 1000; i++) {
            final int j = i;
            mtpe.runTask(new Runnable() {

                @Override
                public void run() {
                    System.out.println(j);
                }

            });
        }
    }
}

Try executing this code a few times. It normally print outs the number on console and when all threads end, it exists. But at times, it finished all task and then is not getting terminated. The thread dump is as follows:

MyThreadPoolExecutor [Java Application] 
    MyThreadPoolExecutor at localhost:2619 (Suspended)  
        Daemon System Thread [Attach Listener] (Suspended)  
        Daemon System Thread [Signal Dispatcher] (Suspended)    
        Daemon System Thread [Finalizer] (Suspended)    
            Object.wait(long) line: not available [native method]   
            ReferenceQueue<T>.remove(long) line: not available    
            ReferenceQueue<T>.remove() line: not available    
            Finalizer$FinalizerThread.run() line: not available 
        Daemon System Thread [Reference Handler] (Suspended)    
            Object.wait(long) line: not available [native method]   
            Reference$Lock(Object).wait() line: 485 
            Reference$ReferenceHandler.run() line: not available    
        Thread [pool-1-thread-1] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-2] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-3] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-4] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-6] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-8] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-5] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-10] (Suspended)   
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-9] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [pool-1-thread-7] (Suspended)    
            Unsafe.park(boolean, long) line: not available [native method]  
            LockSupport.park(Object) line: not available    
            AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
            ArrayBlockingQueue<E>.take() line: not available  
            ThreadPoolExecutor.getTask() line: not available    
            ThreadPoolExecutor$Worker.run() line: not available 
            Thread.run() line: not available    
        Thread [DestroyJavaVM] (Suspended)  
    C:\Program Files\Java\jre1.6.0_07\bin\javaw.exe (Jun 17, 2010 10:42:33 AM)  

In my actual application,ThreadPoolExecutor threads go in this state and then it stops responding.

Regards, Ravi Rao