Event Driven Future - Thread Pool

Question

We use callable<V> and Future<V> to receive the result of a terminated thread from a thread pool. We should call get() to receive the returned result. My problem is: it is not event driven. Is there any framework to get result like SIGCHLD for child processes in C? I want something like this:(the thread pool will call this function when each thread in the pool finished the job)

public void fetchResult(Thread t, Runnable r, Future<Integer> result) {
    Integer x = result.get();
    /* handle x */
    /* also we have Thread and Runnable object that has terminated */
}

Can you please express it more? It is still not clear what you exactly want — Jatin, Oct 23 '11 at 18:01
What part of "event-driven" is important to you? I'm assuming that it is not the lack of busy-waiting, since Future.get() doesn't busy-wait. — Avi, Oct 23 '11 at 20:07
@Avi: It doesn't busy-wait but it locks. I don't want to lock. I want main thread do some job. when a thread from pool terminates the pool calls a function and in that function when I call `Future.get()` it returns immediately. — Majid Azimi, Oct 24 '11 at 18:19

score 1 · Accepted Answer · answered Oct 28 '11 at 18:58

1

you might want to check out the ThreadPoolExecutor.afterExecute() method. it's called after each task completes. you could create a custom subclass of ThreadPoolExecutor which has the event based callback behavior you desire.

answered Oct 28 '11 at 18:58

jtahlborn

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Johan Sjöberg · Answer 2 · 2011-10-23T18:10:08.230

You could easily create an event driven template. The following pseudo-code illustrates one approach.

abstract class EventTemplate<T> implements Runnable {
    private BlockingQueue<T> queue; 

    public void submit(Callable<T> callable) {
        queue.add(callable);
    }

    public abstract void handleEvent(T t);

    public void run() {
        for(;;) handleEvent(queue.take());
    }

    public void start() {
         new Thread(this).start();
    }
}

Classes can the extend the template

class FooEventHandler extends EventTemplate<Foo> {
    public void handleEvent(Foo foo) {
        // do something 
    }
}

Which can be instantiated

new FooEventHandler().start();

where does the Callable actually get executed? – jtahlborn Oct 28 '11 at 19:01 — jtahlborn, Oct 28 '11 at 19:01

Event Driven Future - Thread Pool

2 Answers2