jpos3 ISOServer shutdown thread deadlock

[swyow]

org.jpos.iso.ISOServer

public void shutdown () {
    shutdown = true;
    executor.submit(() -> {
        Thread.currentThread().setName("ISOServer-shutdown");
        shutdownServer();
        if (!cfg.getBoolean("keep-channels")) {
            shutdownChannels();
        }
    });
}
private void shutdownServer () {
    try {
        if (serverSocket != null) {
            serverSocket.close ();
            fireEvent(new ISOServerShutdownEvent(this));
        }
        executor.awaitTermination(LONG_RELAX, TimeUnit.SECONDS);
    } catch (IOException | InterruptedException e) {
        fireEvent(new ISOServerShutdownEvent(this));
        Logger.log (new LogEvent (this, "shutdown", e));
    }
}

Executor.awaitTermination(LONG_RELAX, TimeUnit.SECONDS) in shutdownServer() will not succeed until a timeout occurs.

It is trying to wait for its own thread to finish. The executor submits a task, and the task waits for the executor to complete all tasks, resulting in a deadlock. Only after the LONG_RELAX timeout may the code continue to shut down channels.

And LONG_RELAX is 5000 seconds, which is too long before the channels can be shut down.
The suggestion fix is to remove awaitTermination, or to break the shutdown server and shutdown channel into two threads, with only the first completing before the second is called.

Please advise.

[ar]

Need to test it but at first sight you have a very valid point. The awaitTermination needs to go up inside the shutdown method.

[swyow]

It has been tried in our lab, and because we need to dynamically start/stop QServer, it prevented us from upgrading to jpos3, hopefully to get a patch soon, thanks.

[ar]

Issue has been confirmed and fixed in a17bafd. Feel free to reopen @swyow if the fix doesn't work for you.

[swyow]

tested and working, thanks @ar