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Re: tsan tests randomly failing
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Paolo Carlini <paolo dot carlini at oracle dot com>
- Cc: "'gcc at gcc dot gnu dot org'" <gcc at gcc dot gnu dot org>, Dodji Seketeli <dodji at redhat dot com>
- Date: Wed, 22 Jan 2014 19:12:54 +0100
- Subject: Re: tsan tests randomly failing
- Authentication-results: sourceware.org; auth=none
- References: <52E00863 dot 2060905 at oracle dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Wed, Jan 22, 2014 at 07:05:23PM +0100, Paolo Carlini wrote:
> a couple of tsan tests:
>
> c-c++-common/tsan/simple_race.c
> g++.dg/tsan/default_options.C
>
> relatively often fail for me at various optimization levels (eg, in
> my last run the former at -O2: no WARNING: ThreadSanitizer... thus
> the test failed).
>
> Is this a known issue? The machine I'm talking about is otherwise
> very stable (i980x, glibc2.18, nothing special)
Yes, this is known, unfortunately the implementation of libtsan is
in itself racy, thus it sometimes doesn't report a problem when it should.
See
https://groups.google.com/forum/#!topic/thread-sanitizer/KIok3F_b1oI
We have yet to decide what to do with the tests, either kill them
altogether, add some nanosleeps to increase probability of succeeding,
run the test internally several times until the problem is reported, etc.
Jakub