How to find out why application didn't finish the execution?

Question

I have an application which has last statement System.out.println("Done");, it is written but after that the program is still running. How can I check why is it running?

Is it ok to use System.exit(0)?

The app is using only one (main) thread. Everything after Done is:

 System.out.println("Done.");

    } catch (ClassNotFoundException | SQLException e) {
        e.printStackTrace();
    }
}

}

Could it be database connection?

Probably there is still a non-daemon thread running. Try to list all right after printing "Done": http://stackoverflow.com/questions/1323408/get-a-list-of-all-threads-currently-running-in-java — PeterMmm, Oct 23 '14 at 09:35
If your application is running in one JVM, then you can use System.exit(0) to stop the JVM. Otherwise your application is running on multiple JVM instance, then you have to stop all JVM instances. — Dhanushka Gayashan, Oct 23 '14 at 09:36
I know that and I also dont know what could prevent it from exiting .. I use only one thread .. last statement is written out .. so what. — Ondrej Tokar, Oct 23 '14 at 09:45
Read http://www.sscce.org/ and include a complete example program that allows us to reproduce your problem. — , Oct 23 '14 at 09:48

score 1 · Accepted Answer · answered Oct 23 '14 at 10:00

Generate a thread-dump when you think the program has finished and look at the output to see where execution currently is. You may find it is not where you expect.

On Unix you should be able to do this using the kill -QUIT command (where pid is your process id). I believe on Windows you can use Ctrl + Break to do the same.

score 0 · Answer 2 · answered Dec 08 '15 at 17:00

We've just had a similar issue (albeit with a Ruby test system).

It turns out we'd run subprocesses which had become detached from the parent process, were hung waiting for something, but still held the stdout open, preventing our stream-monitoring loop from terminating, and holding the process alive.

I located the issue by running 'lsof' on the process that had apparently hung, seeing it had PIPEs still open, and tracking those down with more lsof.

How to find out why application didn't finish the execution?

2 Answers2