進程不退出

ExecutorService handlePool = Executors.newFixedThreadPool(sinkThreadNum);
        for (int i = 0; i < sinkThreadNum; ++i) {
            Thread thread = new SinkTask(i);
            thread.setDaemon(true);
            handlePool.submit(thread);
        }

        latch.await();
        Thread.sleep(1000*60);
        handlePool.shutdown(); //進程不會退出
        //handlePool.shutdownNow(); // 強制關閉資源，進程退出




public void run() {
            MetricValue metricValue = null;
            BlockingQueue<MetricValue> queue = queues.getQueue(index);
            while (true) {
                try {
                    metricValue = queue.poll();
                    if (metricValue == null) {
                        System.out.println("queue 已經空了, index=" + this.index);
                        metricValue = queue.take(); // 線程被阻塞在這裏，使進程不會退出。 handlePool.shutdown()並不能清理資源。
                                             //  shutdownNow()會給線程發中斷信號
                    }
                    doWork(metricValue);
                } catch (Exception e) {
                    return;
                }
            }
        }