Executor interface in java.util.concurrent package lets you submit Runnable tasks. Executor then handles the execution of the task. This interface provides a way of decoupling task submission from the mechanics of how each task will be run, including details of thread use, scheduling, etc.

Contract of Executor interface has a single method: execute(Runnable command)

This Executor implementation uses a Lock to pause/resume the execution.

public class PausableExecutor extends ThreadPoolExecutor {

    private boolean isPaused = false;
    private Lock pauseLock = new ReentrantLock();
    private Condition unpaused = pauseLock.newCondition();

    public PausableExecutor() {
        super(5, 5, 1, TimeUnit.MINUTES, new LinkedBlockingQueue<>());
    }

    @Override
    protected void beforeExecute(Thread t, Runnable r) {
        super.beforeExecute(t, r);
        pauseLock.lock();
        try {
            while (isPaused) {
                unpaused.await();
            }
        } catch (InterruptedException e) {
            t.interrupt();
        } finally {
            pauseLock.unlock();
        }
    }

    public void pause() {
        pauseLock.lock();
        try {
            isPaused = true;
        } finally {
            pauseLock.unlock();
        }
    }

    public void resume() {
        pauseLock.lock();
        try {
            isPaused = false;
            unpaused.signal();
        } finally {
            pauseLock.unlock();
        }
    }
}

 

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