Question

I have a Java threadpool created via Executors.newFixedThreadPool() that I want to use daemon threads.

The reason is that this is a GUI app and I don’t want these threads to cause the program to stay running after the Window is closed.

I implemented a custom ThreadFactory that sets Thread.setDaemon(true) on the threads it creates.

The class is this:

import java.util.concurrent.ThreadFactory;

public class DaemonThreadFactory implements ThreadFactory{

    public Thread newThread(Runnable runnable){
        Thread thread = new Thread();
        thread.setDaemon(true);
        return thread;
    }

}

For some reason when I use DaemonThreadFactory with Executors.newFixedThreadPool() none of my queued tasks are executed. If I change it back to regular ThreadFactory it works.

What am I doing wrong?

Answer 1

You’re not passing the Runnable to the thread, so there’s no code to execute:

@Override
public Thread newThread(Runnable runnable)
{
    Thread thread = new Thread(runnable);
    thread.setDaemon(true);
    return thread;
}