Question

I have a Runnable implementing class which will be run from a Executors.newFixedThreadPool
Inside the Runnable, I have an infinite-loop running which listens on an UDP Port for incoming data.

I want to gracefully end the Runnable in order to close said UDP Ports.

How can I achieve this?
When extending Thread directly, I have access to interrupt() and isInterupted() etc. on which I can base my infinite loop.

In the Runnable implementing class however, I want to to do something like

@Override
public void run() {
    while (active) {

    }
}

and have

private boolean active = true;

How can I set active = false when the ThreadPool is terminated?

Answer 1

You can access the interrupt flag of the current thread using the static method Thread.interrupted(), e.g. instead of your active flag use:

public void run() {
    try {
        // open your ports
        while (!Thread.interrupted()) {
            // do stuff
        }
    } finally {
        // close your ports in finally-block
        // so they get closed even on exceptions
    }
}

And when you want to shutdown your ExecutorService, call shutdownNow() on it. This will interrupt() any running worker threads and have your Runnable break out of its loop.