Class VirtualExecutorService

  extended by java.util.concurrent.AbstractExecutorService
      extended by org.jboss.netty.util.VirtualExecutorService
All Implemented Interfaces:
Executor, ExecutorService

public class VirtualExecutorService
extends AbstractExecutorService

A delegating ExecutorService with its own termination management.

VirtualExecutorService is used when you want to inject an ExecutorService but you do not want to allow the explicit termination of threads on shutdown request. It is particularly useful when the ExecutorService to inject is shared by different components and the life cycle of the components depend on the termination of the injected ExecutorService.

 ExecutorService globalExecutor = ...;
 ExecutorService virtualExecutor = new VirtualExecutorService(globalExecutor);

 ChannelFactory factory =
         new NioServerSocketChannelFactory(virtualExecutor, virtualExecutor);

 // ChannelFactory.releaseExternalResources() shuts down the executor and
 // interrupts the I/O threads to terminate all I/O tasks and to release all
 // resources acquired by ChannelFactory.

 // Note that globalExecutor is not shut down because VirtualExecutorService
 // implements its own termination management. All threads which were acquired
 // by ChannelFactory via VirtualExecutorService are returned to the pool.
 assert !globalExecutor.isShutdown();

The differences from an ordinary ExecutorService

A shutdown request (shutdown() or shutdownNow()) does not shut down its parent Executor but simply sets its internal flag to reject further execution request.

shutdownNow() interrupts only the thread which is executing the task executed via VirtualExecutorService.

awaitTermination(long, TimeUnit) does not wait for real thread termination but wait until VirtualExecutorService is shut down and its active tasks are finished and the threads are returned to the parent Executor.

$Rev: 2122 $, $Date: 2010-02-02 11:00:04 +0900 (Tue, 02 Feb 2010) $
The Netty Project, Trustin Lee

Constructor Summary
VirtualExecutorService(Executor parent)
          Creates a new instance with the specified parent Executor.
Method Summary
 boolean awaitTermination(long timeout, TimeUnit unit)
 void execute(Runnable command)
 boolean isShutdown()
 boolean isTerminated()
 void shutdown()
 List<Runnable> shutdownNow()
Methods inherited from class java.util.concurrent.AbstractExecutorService
invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor, submit, submit, submit
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public VirtualExecutorService(Executor parent)
Creates a new instance with the specified parent Executor.

Method Detail


public boolean isShutdown()


public boolean isTerminated()


public void shutdown()


public List<Runnable> shutdownNow()


public boolean awaitTermination(long timeout,
                                TimeUnit unit)
                         throws InterruptedException


public void execute(Runnable command)

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