Java shutdown hook not running

Question

I have a product service in Java. In our code I am creating shut down hook, but when I stop service it is not calling shut down hook consistently. Out of 5 stop calls it has called shutdown hook only once.

Runnable shutdownHandler = new Runnable() {

    @Override
    public void run() {

        s_log.info("Shutting down thread..");
    }

};

Runtime.getRuntime().addShutdownHook(
        new Thread(shutdownHandler, "shutdownthread"));

Can anybody please tell me what could be the reason behind this not getting called consistently?

How is the process being shutdown? Depending on how it is killed, it might not get a chance to run the shutdown hook. You should never assume it will be run as the process could be killed in such a way it can't be run. — Peter Lawrey, Mar 09 '16 at 20:31
Its a standard java process registered in windows. I am stopping service from service console of windows — user1108687, Mar 09 '16 at 20:34
What service runner are you using? Java doesn't have a built-in runner. — Andreas, Mar 09 '16 at 20:42
Do you have a proof that the hook doesn't run in those cases? Logging a message *is not a proof* since some logging frameworks ([e.g. Log4j2](http://stackoverflow.com/questions/17400136/how-to-log-within-shutdown-hooks-with-log4j2)) have their own shutdown hooks and thus may be already shut down when you attempt to use the logging method. — Jiri Tousek, Mar 09 '16 at 20:43
Java doesn't have a standard way to be installed as a windows service. Are you using a tool or framework to do this? — Peter Lawrey, Mar 09 '16 at 20:44
We are using tomcat server to run our java application and that is registered as a windows service. — user1108687, Mar 09 '16 at 20:47
Possible duplicate of [Java Shutdown hook not run](http://stackoverflow.com/questions/12404712/java-shutdown-hook-not-run) — shoover, Mar 09 '16 at 22:19

score 1 · Answer 1 · answered Dec 22 '19 at 14:51

Check the following code:

Runnable shutdownHandler = new Runnable() {
    @Override
    public void run() {
        System.out.println("Shutting down thread..");
    }
};

Runtime.getRuntime().addShutdownHook(
        new Thread(shutdownHandler, "shutdownthread"));

and if it gives you expected output, you need to check the documentation of your logging framework.

score 0 · Answer 2 · edited Dec 18 '21 at 08:37

I am also finding that my framework (Jooby) and Java shutdown hooks work fine on my Mac on IntelliJ which sends a kill SIGINT (-2) however on Ubuntu Server 20.04 LTS they don't run.

As my Java app is a webapp I came up with a simple workaround:

Setup a controller to listen to some url that isn't easily guessable e.g.
```
/exit/fuuzfhuaBFDUWYEGLI823y82941u9y47t3u45
```
Have the controller simply do the following:
```
System.exit(0)
```

Do a curl or wget from a script to the URL and the shutdown hooks all fire as JVM comes down.

I suspect for some reason on Linux there is a bug and no matter what interrupt that I use besides SIGKILL they all effectively behave like SIGKILL and the JVM comes down hard/abruptly.

Java shutdown hook not running

2 Answers2