How does a JVM running multiple threads handle ctrl-c, w/ and w/o shutdown hooks?

Question

Could not find this answer online. When Ctrl+C is hit:

• When we don't have any shutdown hook, what happens to the running threads - do they each get hit with an InterruptedException?
• When we have shutdown hook(s), I know that the shutdown hooks get run in new threads in arbitrary order. But what happens to the existing running threads? Do they still each get hit with an InterruptedException?

Thanks!

Answer 1

The classic book "Java Concurrency in Practice" has a chapter (7.4) on the JVM shutdown, you should read that, but here are some relevant quotes:

If any application threads (daemon or nondaemon) are still running at shutdown time, they continue to run concurrently with the shutdown process.

The JVM makes no attempt to stop or interrupt any application threads that are still running at shutdown time; they are abruptly terminated when the JVM eventually halts.

So the threads are not interrupted, but you can interrupt them explicitly from the shutdown hook, if you wish.

Answer 2

IMO, Daemon threads will continue to run during shutdown process and JVM will kill all running threads later when its time to exit the application. I don't think, running threads will get InterruptedException as JVM doesn't make any extra effort to stop running threads.

http://www.tutorialspoint.com/java/lang/runtime_addshutdownhook.htm