private synchronized Runnable getTask(int threadid) throws InterruptedException {
		while(workQueue.size() == 0) {
			if(isClosed) return null;
			System.out.println("߳"+threadid+"ȴ...");
			wait();				//û,͵ȴ
		}
		System.out.println("߳"+threadid+"ʼִ...");
		return (Runnable) workQueue.removeFirst(); //ضеһԪ,Ӷɾ
	}