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From: George Bosilca (bosilca_at_[hidden])
Date: 2007-09-21 10:40:21


Tim,

Valgrind will not help ... It can help with double free or things
like this, but not with over-running memory that belong to your
application. However, in Open MPI we have something that might help
you. The option --enable-mem-debug add a unused space at the end of
each memory allocation and make sure we don't write anything there. I
think this is the simplest way to pinpoint this problem.

   Thanks,
     george.

On Sep 21, 2007, at 10:07 AM, Tim Prins wrote:

> Aurelien and Brian.
>
> Thanks for the suggestions. I reran the runs with --without-memory-
> manager and
> got (on 2 of 5000 runs):
> *** glibc detected *** corrupted double-linked list: 0xf704dff8 ***
> on one and
> *** glibc detected *** malloc(): memory corruption: 0xeda00c70 ***
> on the other.
>
> So it looks like somewhere we are over-running our allocated space.
> So now I
> am attempting to redo the run with valgrind.
>
> Tim
>
> On Thursday 20 September 2007 09:59:14 pm Brian Barrett wrote:
>> On Sep 20, 2007, at 7:02 AM, Tim Prins wrote:
>>> In our nightly runs with the trunk I have started seeing cases
>>> where we
>>> appear to be segfaulting within/below malloc. Below is a typical
>>> output.
>>>
>>> Note that this appears to only happen on the trunk, when we use
>>> openib,
>>> and are in 32 bit mode. It seems to happen randomly at a very low
>>> frequency (59 out of about 60,000 32 bit openib runs).
>>>
>>> This could be a problem with our machine, and has showed up since I
>>> started testing 32bit ofed 10 days ago.
>>>
>>> Anyways, just curious if anyone had any ideas.
>>
>> As someone else said, this usually points to a duplicate free or the
>> like in malloc. You might want to try compiling with --without-
>> memory-manager, as the ptmalloc2 in glibc frequently is more verbose
>> about where errors occurred than is the one in Open MPI.
>>
>> Brian
>> _______________________________________________
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>
>
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