使用executor.shutdown（）

Question

Look at the following piece of code:

     public void pinger()
     {
        ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1);
        executor.scheduleAtFixedRate(runnable, start, rate, TimeUnit.SECONDS);
        executor.shutdown();
     }

Is there any use of writing the shutdown command in this case? Different clients would create their own runnable objects and invoke this function.

Answer 1

When you shutdown an executor, no new task will be accepted. Since you create a new one inside the pinger method every task has its own executor. A shutdown as you write will only free resource once the corrent task is terminated.

Answer 2

Some notes:

1. You should not create Executor for each client request.
2. Create Executor out side of client request and submit tasks to Executor
3. When you decide that you should not accept new tasks to Executor , then shutdown the executor. The right way of shutting down Executor is explained in below post:

How to forcefully shutdown java ExecutorService