harmony-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Alexey Varlamov" <alexey.v.varla...@gmail.com>
Subject Re: [launcher] Uncaught exceptions not printed on J9 VME
Date Mon, 15 Oct 2007 04:50:53 GMT
2007/10/14, Gregory Shimansky <gshimansky@apache.org>:
> Oliver Deakin wrote:
> > Hi all,
> >
> > A little while back there was a thread called "[drlvm] Should the
> > launcher print uncaught exceptions?" [1] where we discussed the fact
> > that running a test case like [2] did not print a stack trace with the
> > Harmony launcher. As part of this discussion, HARMONY-1819 was raised
> > and the line "(*jvm)->DetachCurrentThread(jvm)" was added to the
> > launcher main.c in repo revision r464443.
> >
> > HARMONY-3713 was later raised pointing out that calling
> > DetachCurrentThread() to detach the main thread was contrary to the spec
> > [3], and the line was removed from main.c. However, I have just noticed
> > that if you run [2] on the current J9 VME (and, in fact, on the RI with
> > a simple launcher) you do not get any stack trace printed, and I imagine
> > this has been the case since the commit of HARMONY-3713.
> >
> > The RI has a bug [4], contrary to the spec [3], which requires
> > DetachCurrentThread() to be called by the invoking launcher if you wish
> > to see the stack trace of an uncaught exception. It appears that J9 has
> > matched this bug, probably so no unexpected trace is printed in
> > launchers programmed against the RI.
> >
> > So currently running Harmony classlib with the J9 VME will not result in
> > any stack trace being printed for uncaught exceptions, which makes
> > debugging issues where that occurs more troublesome. Id like to propose
> > that the DetachCurrentThread() line be readded to main.c (i.e. the
> > opposite of the patch for HARMONY-3713), perhaps with a comment to show
> > that this is to match the behaviour of the RI rather than the spec.
> >
> > Any objections?
>
> I wonder if simply adding
>
> if ((*env)->ExceptionCheck(env))
>     (*env)->ExceptionDescribe(env);
>
> is enough to print out stack trace in the main thread without violating
> the spec.
>

The bug of RI [4] (fixed in 1.5) being referred by Oliver is a bit
wider than just printing out the stack trace. Synopsis reads:
"(thread) setUncaughtExceptionHandler() doesn't work on main thread ".
I believe this is really strong argument to use DetachCurrentThread
and be compatible with RI rather than spec (which should be fixed and
will be someday ;)
Moreover, I suggest to add a regression test for this issue (like the
one in [4]) so the decision would stay locked in.

[4] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4992454
--
Alexey

>
> --
> Gregory
>
>

Mime
View raw message