Shafagh,

I missed the dependence on the number of processors. Apparently there is some thread support.

Doug
On Oct 4, 2008, at 5:29 PM, Shafagh Jafer wrote:

Doug Reeder,
Daniel is saying that the problem only occurs in openmpi when running more than 16 processes. So could that still be cause becasue openmpi does not support threads??!!

--- On Fri, 10/3/08, Doug Reeder <dlr@rain.org> wrote:
From: Doug Reeder <dlr@rain.org>
Subject: Re: [OMPI users] segfault issue - possible bug in openmpi
To: "Open MPI Users" <users@open-mpi.org>
Date: Friday, October 3, 2008, 2:40 PM

Daniel,

Are you using threads. I don't think the opempi-1.2.x work with threads.

Doug Reeder
On Oct 3, 2008, at 2:30 PM, Daniel Hansen wrote:

Oh, by the way, here is the segfault:

[m4b-1-8:11481] *** Process received signal ***
[m4b-1-8:11481] Signal: Segmentation fault (11)
[m4b-1-8:11481] Signal code: Address not mapped (1)
[m4b-1-8:11481] Failing at address: 0x2b91c69eed
[m4b-1-8:11483] [ 0] /lib64/libpthread.so.0 [0x33e8c0de70]
[m4b-1-8:11483] [ 1] /fslhome/dhansen7/openmpi/lib/libmpi.so.0 [0x2aaaaabea7c0]
[m4b-1-8:11483] [ 2] /fslhome/dhansen7/openmpi/lib/libmpi.so.0 [0x2aaaaabea675]
[m4b-1-8:11483] [ 3] /fslhome/dhansen7/openmpi/lib/libmpi.so.0(mca_pml_ob1_send+0x2da) [0x2aaaaabeaf55]
[m4b-1-8:11483] [ 4] /fslhome/dhansen7/openmpi/lib/libmpi.so.0(MPI_Send+0x28e) [0x2aaaaab52c5a]
[m4b-1-8:11483] [ 5] /fslhome/dhansen7/compute/for_DanielHansen/replica_mpi_marylou2/Openmpi_md_twham(twham_init+0x708) [0x42a8a8]
[m4b-1-8:11483] [ 6] /fslhome/dhansen7/compute/for_DanielHansen/replica_mpi_marylou2/Openmpi_md_twham(repexch+0x73c) [0x425d5c]
[m4b-1-8:11483] [ 7] /fslhome/dhansen7/compute/for_DanielHansen/replica_mpi_marylou2/Openmpi_md_twham(main+0x855) [0x4133a5]
[m4b-1-8:11483] [ 8] /lib64/libc.so.6(__libc_start_main+0xf4) [0x33e841d8a4]
[m4b-1-8:11483] [ 9] /fslhome/dhansen7/compute/for_DanielHansen/replica_mpi_marylou2/Openmpi_md_twham [0x4040b9]
[m4b-1-8:11483] *** End of error message ***



On Fri, Oct 3, 2008 at 3:20 PM, Daniel Hansen <dhansen@byu.net> wrote:
I have been testing some code against openmpi lately that always causes it to crash during certain mpi function calls.  The code does not seem to be the problem, as it runs just fine against mpich.  I have tested it against openmpi 1.2.5, 1.2.6, and 1.2.7 and they all exhibit the same problem.  Also, the problem only occurs in openmpi when running more than 16 processes.  I have posted this stack trace to the list before, but I am submitting it now as a potential bug report.  I need some help debugging it and finding out exactly what is going on in openmpi when the segfault occurs.  Are there any suggestions on how best to do this?  Is there an easy way to attach gdb to one of the processes or something??  I have already compiled openmpi with debugging, memory profiling, etc.  How can I best take advantage of these features?

Thanks,
Daniel Hansen
Systems Administrator
BYU Fulton Supercomputing Lab

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