I create the following executor in a singleton:
final private ExecutorService executor = Executors.newSingleThreadExecutor(new ThreadFactory() { final ThreadFactory delegate = Executors.defaultThreadFactory(); public Thread newThread(Runnable paramAnonymousRunnable) { Thread localThread = this.delegate.newThread(paramAnonymousRunnable); localThread.setName("MyTask-" + localThread.getName()); localThread.setDaemon(XXX.this.daemonThread); return localThread; } }); And during the execution of the program, there a lot call to this method of the singleton. The calls are done in different threads and maybe at the sametime.
private void send(final String paramString) { try { this.executor.execute(new Runnable() { public void run() { //DO some interesting stuff } }); } catch (Exception localException) { this.handler.handle(localException); } }
And at some point the following stacks start to appear:
java.util.concurrent.RejectedExecutionException at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1774) at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:768) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:656) at java.util.concurrent.Executors$DelegatedExecutorService.execute(Executors.java:589) at XXXXX.send(XXXX.java:269) Why the jvm will throw such exception?
The singleThreadExecutor is backed by a LinkedBlockingQueue().
And the thread pool wasn't shutdown.
for information, the jvm is oracle jdk 1.6. The singleton is created with spring. copy from java.util.concurrent.Executors:
public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) { return new FinalizableDelegatedExecutorService (new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), threadFactory)); } 4 Answers
There are two reasons why execute would throw a RejectedExecutionException
- The queue is full and you cannot add any more threads
- The ThreadPool has been shutdown
Since you are using a LinkedBlockingQueue the only way I can see this occurring is because you shutdown the pool.
You might have submitted tasks after calling executor.shutdown(). Normally to stop executor they do
executor.shutdown(); executor.awaitTermination(10, TimeUnit.MINUTES); Maybe you should use a thread pool instead of using a single executor.
executor = new java.util.concurrent.ThreadPoolExecutor(30, 30, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new ThreadFactory() { final AtomicInteger threadNumber = new AtomicInteger( 1 ); @Override public Thread newThread(Runnable r) { return new Thread(r, "Thread No : " + threadNumber.getAndIncrement()); } }); Threads are not available to execute the given task. No linked block queue to que task.
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