Question

i have this scenario:

class MyClass {
   Producer p;
   Consumer c;
    public static void main(String[] args){
        BlockingQueue q = new LinkedBlockingQueue();
        p = new Producer(q);
        c = new Consumer(q);
        Thread t = new Thread(p);
        t.start();
        new Thread(c).start();
        while (true) {
            if (!p.getContinuer()) {
                c.setContinuer(false);
                System.out.println("here:"+p.getContinuer().toString());
                break;
            }
        }
        System.out.println("finish all");
     }
}

class Producer implements Runnable {
private final BlockingQueue queue;
private AtomicBoolean continuer = new AtomicBoolean(true);
   public Boolean getContinuer() {
      return continuer.get();
   }
    @Override
    public void run() {
      while(true){
        //open socket
        //read data from socket
        queue.put(data);
        if(end){
            System.out.println("Shutting down Producer");
            continuer.getAndSet(false);
        }
      }
    }
}

class Consumer implements Runnable {
    private final BlockingQueue queue;
    private static AtomicBoolean continuer = new AtomicBoolean(true);

    public void setContinuer(Boolean continuerr) {
        continuer = new AtomicBoolean(continuerr);
    }

    public Boolean getContinuer() {
        return continuer.get();
    }

    @Override
    public void run() {
          while (getContinuer()) {
             //Do some work
             consume(queue.take());
          }
          System.out.println("shut down Consumer");
    }
}

this is what i’m getting:

Shutting down Producer

here:false

finish all

that means that the consumer still working, and the variable “continuer” isin’t updated.

i saw also this and this posts, i tried it, but nothing changed.

what’s my problem ?

EDIT: i changed my code, and apparently the consumer is blocked (waiting if no elements are present on this queue. ) when trying to read data from the BlockingQueue (see consume(queue.take()); in the consumer class).

Answer 1

Well,

public void setContinuer(Boolean continuerr) {
    continuer = new AtomicBoolean(continuerr);
}

Looks wrong. Why don’t you

public void setContinuer(boolean continuerr) {
    continuer.set(continuerr);
}

---

Furthermore, if the end variable is not volatile, it may be cached in threads.

---

We will need to see more code. (Or at least compiling code.) Because this code works as expected:

import java.util.concurrent.*;

public class MyClass {
    static Producer p;
    static Consumer c;

    public static void main(String[] args) {
        BlockingQueue q = new LinkedBlockingQueue();
        p = new Producer();
        c = new Consumer();
        Thread t = new Thread(p);
        t.start();
        new Thread(c).start();
        while (true) {
            if (!p.getContinuer()) {
                c.setContinuer(false);
                break;
            }
        }
        System.out.println("finish all");
    }
}

class Producer implements Runnable {
    private boolean end = true;
    private BlockingQueue queue;
    private AtomicBoolean continuer = new AtomicBoolean(true);

    public boolean getContinuer() {
        return continuer.get();
    }

    @Override
    public void run() {
        while (true) {
            // open socket
            // read data from socket
            if (end) {
                System.out.println("Shutting down Producer");
                continuer.getAndSet(false);
                break;
            }
        }
    }
}

class Consumer implements Runnable {
    private BlockingQueue queue;
    private static AtomicBoolean continuer = new AtomicBoolean(true);

    public void setContinuer(Boolean continuerr) {
        continuer = new AtomicBoolean(continuerr);
    }

    public Boolean getContinuer() {
        return continuer.get();
    }

    @Override
    public void run() {
        while (getContinuer()) {
            // Do some work
        }
        System.out.println("shut down Consumer");
    }
}

It prints

Shutting down Producer
finish all
shut down Consumer

---

Regarding your edit:

i changed my code, and apparently the consumer is blocked (waiting) when trying to read data from the BlockingQueue (see consume(queue.take()); in the consumer class).

You should, after your c.setContinuer(false); do consumerThread.interrupt(). The consumer thread that’s blocked in the read method, will throw an InterruptedException, (which you may ignore), and then exit the loop and terminate gracefully.