Question

What is the best way to handle RejectedExecutionException while using a ThreadPoolExecutor in Java?

I want to ensure that the task submitted should not be overlooked and should surely get executed. As of now there are no hard real time requirements to get the task done.

One of the things I thought could be done was waiting in a loop till I know that there is space in the runnable queue, and then go on and add it to the queue.

Would be glad if people can share their experiences.

Adding the possible solution I though of:

while(executor.getQueue().remainingCapacity <= 0){
// keep looping
Thread.sleep(100);
};
//if the loop exits ,indicates that we have space in the queue hence 
//go ahead and add to the queue 
executor.execute(new ThreadInstance(params));

Answer 1

I would change the behaviour of your queue. e.g.

public class MyBlockingQueue<E> extends ArrayBlockingQueue<E> {
    private final long timeoutMS;

    public MyBlockingQueue(int capacity, long timeoutMS) {
        super(capacity);
        this.timeoutMS = timeoutMS;
    }

    @Override
    public boolean offer(E e) {
        try {
            return super.offer(e, timeoutMS, TimeUnit.MILLISECONDS);
        } catch (InterruptedException e1) {
            Thread.currentThread().interrupt();
            return false;
        }
    }
}

This will wait for the queue to drain before giving up.