There are a couple things you can try.  The Sun JVM is pretty
good about not crashing without letting you know what's going
on.  It might be your app is ending normally due to a logic error
you did not anticipate.  I'd try the following:

1. Run the JVM in -verbose mode, see if it spits out anything
  unexpected or interesting.
2. Run the app in a java debugger and trace the method calls on
  the various threads to see where the app is going.  How you
  do this varies greatly from one debugger to another.  jdb
  will work, see the "trace methods [threadid]" command.
3. Add a shutdown hook to your code to see if it gets called.
  If not, the JVM likely exited abnormally.  See
  java.lang.Runtime.addShutdownHook() for details.
4. if the shutdown hook is NOT getting called, run your app
  inside the Sun workshop debugger, dbg.  It does a better job
  of informing you of unexpected signals.  Just be aware here,
  the JVM will normally throw signals around during normal
  operation, so this may not be as helpful as you might expect.
5. Use the profiler to try and see what the app is doing.

I'm sure folks with have other ideas.

--Joe

Maybe run it under a small watchdog process that forks and execs the
Java program, then uses wait() or waitpid() or waitid() or whatever
to keep an eye on it?

Thomas Maslen
maslen@pobox.com