Blocking queue and multi-threaded consumer, how to know when to stop

Question

I have a single thread producer which creates some task objects which are then added into an ArrayBlockingQueue (which is of fixed size).

I also start a

Answer 1

I'd send the workers a special work packet to signal that they should shut down:

public class ConsumerWorker implements Runnable{

private static final Produced DONE = new Produced();

private BlockingQueue inputQueue;

public ConsumerWorker(BlockingQueue inputQueue) {
    this.inputQueue = inputQueue;
}

@Override
public void run() {
    for (;;) {
        try {
            Produced item = inputQueue.take();
            if (item == DONE) {
                inputQueue.add(item); // keep in the queue so all workers stop
                break;
            }
            // process `item`
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

}

To stop the workers, simply add ConsumerWorker.DONE to the queue.