How to monitor status of all threads created by executor service

Question

Is there a way to check the status of all threads created by executor service. Let's say I have 20 threads. How would I check the status of all of them?

Answer 1

If you really want to monitor status of all threads in thread pool,you can try create your ThreadFactory like the below code:

public class SelfThreadFactory implements ThreadFactory {
    private Map<Long, Thread> stateMap = new ConcurrentHashMap<>();

    @Override
    public Thread newThread(Runnable r) {
        Thread thread = new Thread(r);
        stateMap.put(thread.getId(), thread);
        return thread;
    }

    public Map<Long, Thread> getStateMap() {
        return stateMap;
    }
}

Use getStateMap() method you can get all thread created by this ThreadFactory,then you can get state of thread.

Answer 2

You may extend ThreadPoolExecutor and use its methods beforeExecute(Thread t, Runnable r) and afterExecute(Runnable r, Throwable t) to monitor the status of the tasks/threads.

You can find an example implementation in this article