线程池（4）Executors.newScheduledThreadPool-只执行1次

ScheduledExecutorService es = Executors.newScheduledThreadPool(5);
        log.info("开始时间");
        try {
            for (int i = 0; i < 20; i++) {
                Runnable syncRunnable = new Runnable() {
                    @Override
                    public void run() {
                        log.info(Thread.currentThread().getName());
                    }
                };
                es.schedule(syncRunnable, 3000, TimeUnit.MILLISECONDS);
            }
        } finally {
            es.shutdown();
        }

            10:41:39.589 开始时间
            10:41:42.595 pool-1-thread-1
            10:41:42.595 pool-1-thread-2
            10:41:42.595 pool-1-thread-3
            10:41:42.595 pool-1-thread-4
            10:41:42.596 pool-1-thread-2
            10:41:42.596 pool-1-thread-5
            10:41:42.596 pool-1-thread-1
            10:41:42.596 pool-1-thread-3
            10:41:42.597 pool-1-thread-4
            10:41:42.597 pool-1-thread-2
            10:41:42.597 pool-1-thread-5
            10:41:42.597 pool-1-thread-1
            10:41:42.598 pool-1-thread-3
            10:41:42.598 pool-1-thread-4
            10:41:42.598 pool-1-thread-2
            10:41:42.599 pool-1-thread-5
            10:41:42.599 pool-1-thread-1
            10:41:42.600 pool-1-thread-3
            10:41:42.600 pool-1-thread-4
            10:41:42.600 pool-1-thread-2

public ScheduledThreadPoolExecutor(int corePoolSize) {
        super(corePoolSize, Integer.MAX_VALUE, 0, NANOSECONDS,
              new DelayedWorkQueue());
    }