libgcj/289

[Bryce McKinlay]

The following reply was made to PR libgcj/289; it has been noted by GNATS.

From: Bryce McKinlay <bryce@albatross.co.nz>
To: Tom Tromey <tromey@cygnus.com>
Cc: java-gnats@sourceware.cygnus.com
Subject: Re: libgcj/289
Date: Mon, 11 Sep 2000 20:05:45 +1200

 Tom Tromey wrote:
 
 >  I experimented with the JDK.  With the JDK interpreter, if the main
 >  thread throws an uncaught exception and then exits (because that was
 >  the last thread) then the runtime with exit with status 1.
 >
 >  But consider the appended program.  This program attempts to determine
 >  what happens if the main thread throws an exception but is not the
 >  last thread to stop.  In this situation, what should happen?  I don't
 >  know, because the JDK hangs.  (Maybe there is a bug in my test, feel
 >  free to enlighten me.)
 
 Interesting. It seems that in the JDK, a join() on a thread that throws an
 unchecked exception never returns. This behaviour seems reasonable, I guess,
 as a thread that throws an exception could potentially leave objects in an
 unstable state. This is consistent across several different JDK versions (and
 combinations of green/native threads), so perhaps we should look at
 duplicating it.
 
 >  I don't think we should do anything special here.  I agree it is less
 >  than perfect, but it isn't clear what the right thing is, and
 >  compatibility with the JDK seems hard.
 
 If any thread throws unchecked, the JDK will exit with status 1 once the last
 thread dies, unless another thread specifically calls System.exit() with a
 different exit status. It should just be a matter of setting an error flag
 somewhere and checking it in the exit routine.
 
 >  public class q implements Runnable
 >  {
 >    public static Thread t_bad, t_good;
 >
 >
 >    public boolean bad_flag;
 >
 >    public void run () throws InterruptedException
 
 There is a compiler bug here - this declaration should be illegal because
 run() in Runnable does not throw InterruptedException. I can't duplicate this
 for any class/interface other than Runnable, however. Strange.
 
 regards
 
   [ bryce ]