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From: Yvan Fournier (yvan.fournier_at_[hidden])
Date: 2007-09-24 17:27:41


Hello,

I seem to have encountered a new bug in Open MPI 1.2.3 using indexed
datatypes with MPI_Recv (which seems to be of the "off by one" sort).
I have (different from the bug I submitted in 2006 and which was
corrected since).

This bug leads to a segfault, and I have only encountered it one
one data set (on a relatively large set for a 2-processor run).
I have reproduced the segfault on 2 different linux Systems
(Debian Sarge on dual-processor Intel Xeon, Kubuntu 7.04
on single-processor Centrino system).

A means to reproduce it on 2 ranks can be found at :
http://yvan.fournier.free.fr/OpenMPI/ompi_datatype_bug_2.tar.gz

(the program is very simple, but the displacements array required to
reproduce it is too large for the mailing list).

The program does not print any output, but does not segfault when
functioning properly, or when USE_INDEXED_DATATYPE is unset (lines
57-58). It works with LAM 7.1.1 and MPICH2, but fails under Open MPI.
This is a (much) simplified extract from a part of Code_Saturne's
FVM library (http://rd.edf.com/code_saturne/), which otherwise works
fine on most data using Open MPI.

Best regards,

        Yvan Fournier