Do we need to shutdown ExecutorService fixedThreadPool

Question

I have created threadpool using ExecutorService, in my application to call vendor websrvice, using below code.

  ExecutorService executor = Executors.newFixedThreadPool(getThreadPoolSize());
    for (int i = 0; i < list.size(); i++) {
                    Request ecpReq = list.get(i);           
                    thRespLst.add(executor.submit(new Task(ecpReq)));
                }

Wanted to know do we need to take care of shutting down threadpool or something, basically I don't want hanging threads in production environment.

Answer 1

• newFixedThreadPool

public static ExecutorService newFixedThreadPool(int nThreads)

Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue. At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available. If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks. The threads in the pool will exist until it is explicitly shutdown.

Javadocs.

Here a good explanation.

Answer 2

FinalizableDelegatedExecutorService and ThreadPoolExecutor override finalize() to do the shutdown.

/**
* Invokes {@code shutdown} when this executor is no longer
* referenced and it has no threads.
*/
protected void finalize() {
    shutdown();
}

Acutally, I see no reason to explicitly shutdown the ExecutorService.