class GCDExecutorService extends AbstractExecutorService {

    public void shutdown() {
        SecurityManager sm = System.getSecurityManager();
	if ( sm != null ) {
            sm.checkPermission(shutdownPerm);
        }
        try {
            shutdownLock.lock();
            state = State.SHUTDOWN;
            terminateIfDone(queue.operationCount().intValue() == 0);
        } finally {
            shutdownLock.unlock();
        }
    }

    public  GCDExecutorService();

}