How to kill a thread nice in java?

Question

A common question but I haven't found any acceptable answer.

I recently run in to the problem how to kill a thread in a nice way. I try to make a generic message handler that accepts runnables. The problem is that I can't exit the current runnable in a good way and fast enough.

The code in the runnables are unknown i.e. jni, pure java, 3:rd part lib etc. Below is a simple example with sleep that "steels" the interrupt so the thread never exits (fast enough): I wan't to be able to interrupt the thread at any time, only between each task are not acceptable. My first idea was to use thread.stop but that's deprecated.

Producer:

int i = 0;
MessageHandler handler = new MessageHandler();
handler.start();

handler.post(new Runnable() {
    @Override
    public void run() {
        System.out.println("task -" + i++ + " " + Thread.currentThread().getName());
        for (int r=0;r<1000000000;r++) {
            System.out.println("task -" + i++ + " " + Thread.currentThread().getName());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
});

try {
    Thread.sleep(500);
} catch (InterruptedException q) {
    q.printStackTrace();
}
handler.interrupt();

Consumer (MessageHandler):

package test;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

public class MessageHandler extends Thread implements Runnable {

    private BlockingQueue<Runnable> msgQue = new LinkedBlockingQueue<Runnable>();
    private final static String TAG = "MessageHandler";

    public void run() {
        try {
            System.out.println(TAG + " Initialized "  + currentThread().getName());
            while(true) {
                Runnable task = msgQue.take();
                task.run();
                if (isInterrupted()) {
                    break;
                }
            }
        } catch (InterruptedException e) {
            System.out.println(TAG + " InterruptedException "  + currentThread().getName());
        } finally {
            System.out.println(TAG + " Exit "  + currentThread().getName());
            msgQue.clear();
            msgQue = null;
        }
    }

    public void post(Runnable task) {
        System.out.println(TAG + " post " + currentThread().getName());
        msgQue.add(task);
    }
}

I feel like a superman wihout any super power...

Hey, Oracle give my power back!

Answer 1

Check out this faq on why they deprecated Thread.stop() and what to use instead. The gist of it is to use Thread.interrupt().