autoterminating service

[Andrew Gaydenko]

Hi!

I need some kind of executor service which is like java logger is:

- doesn't need explicit shutting down
- executes tasks queue and treminates when all other user's threads are terminated.

The thing is I don't understand how to hook this condition - "all other user's threads are terminated". A daemonizing threads in a pool also doesn't help - threads are interrupted immediately on above condition.

Any tricks?

[Carey Evans]

The actions registered by Runtime.addShutdownHook() will be run when System.exit() is called, when there are no no-daemon threads left, or when Control-C or similar is pressed. Is this what you want?

[Nitesh Kant]

Andrew:
A daemonizing threads in a pool also doesn't help

Can you explain as to why doesnt it help?
If all the worker threads in a pool are daemons then the pool will automatically shutdown when the user threads die i.e. your threadpool will not hold a JVM shutdown.

Toggling thread.setDaemon(true); to true and false will unhold and hold JVM termination:

import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
 
public class TPTestForJR {
 
    public static void main(String[] args) {
        ThreadPoolExecutor executor = 
                new ThreadPoolExecutor(1, 2, 20, TimeUnit.MINUTES, 
                                                        new LinkedBlockingQueue<Runnable>(),
                                                        new MyThreadFactory());
        for (int i=0; i < 10; i++) {
            executor.submit(new Runnable() {
                public void run() {
                    System.out.println("TPTestForJR.run");
                }
            });
        }
    }
 
    private static class MyThreadFactory implements ThreadFactory {
        public Thread newThread(Runnable r) {
            Thread thread = new Thread(r);
            thread.setDaemon(true);
            return thread;
        }
    }
}
   

[ July 07, 2008: Message edited by: Nitesh Kant ]

[Andrew Gaydenko]

It seems like I have resolved the issue. Please, excuse me for cross-foruming (I have created new topic here after some answerless period at SDN) - I have decribed the situation here:

http://forum.java.sun.com/thread.jspa?messageID=10327012

The main conclusion I have got is to not to use java logger for debugging a termination of concurrent app