正常关闭包含连接的Java任务

Question

I have a number of Runnable tasks governed by an executor service.

These tasks are essentially JMS queue pollers and contain their own connections.

For example:

ExecutorService executor = Executors.newFixedThreadPool(...);
executor.submit(new MyListener());

My listener:

public class MyListener implements Runnable {
    @Override
    public void run() {
        // Create my JMS connection here
    }
}

How do I gracefully close the JMS connection in each task and then proceed to shutdown each thread?

I'm having problems shutting down the executor service with shutdown() .

I need to force an interrupt with shutdownNow() , however, how can I be sure that my JMS connection has been closed without me explicitly calling .close() ?

Is there an interface I'm missing that allows shutdown hooks to be executed when I attempt to stop the task?

Answer 1

The easiest would be to use an atomic boolean shared by the class that signals shutdown and the runnable. This tells them to stop. Another option is finding the threads yourself and interrupt them. You would need to catch the interrupted exception and close the connection. You can set the thread names when the runnable launch for easy id.

Answer 2

Here's my solution to gracefully shutdown threads holding a connection, utilising the suggestion of an atomic boolean:

MyRunnable implements Runnable {

    private volatile boolean isActive = true;

    public void run() {
       while(isActive && !Thread.currentThread().isInterrupted()) {
           ...
       }
    }

    public void stop() {
        isActive = false;
    }
}

Main thread:

private void myShutdownHook() {
    myRunnableInstance.stop();

    // Can safely shutdown executor now...
}