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Subject: Re: [OMPI users] Segmentation faults
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-03-17 10:58:02


Sorry for the delay in replying.

You might want to run your code through a debugger, particularly a memory-checking debugger. Your stack trace shows that it's segv'ing in main(), so it might not be that difficult to find.

On Mar 8, 2011, at 12:48 AM, arep isa wrote:

> Hi,
> I need to use Open MPI to distribute 2d-array in the PGM file among 10
> working computers. Then I need to manipulate each value of the array
> to get a negative image (255-i) and then print the output back. I'm
> thinking of using mpi_scatterv and mpi_gatherv to distribute the data.
> After i compile the program, it got segmentation faults. I dont know
> what is the problem whether my code wrong or compiler. I integrate the
> code to read/write pgm from pgm_RW_1.c and the MPI code in exmpi_2.c.
>
> --I install OPEN MPI version 1.4.1-2 via Synaptic Package Manager on
> UBUNTU 10.04.
>
> --I compile with :
> mpicc -o exmpi_2 exmpi_2.c
> --I run for testing (segmentation faults):
> mpirun -np 10 ./exmpi_2 2.pgm out.pgm
> --Then I run with hostfile:
> mpirun -np 10 --hostfile .mpi_hostfile ./exmpi_2 2.pgm out.pgm
>
>
> Here is the error:
> ____________________________________________________________________________
> arep_at_ubuntu:~/Desktop/fyp$ mpirun -np 10 ./exmpi_2 2.pgm out.pgm
> [ubuntu:02948] *** Process received signal ***
> [ubuntu:02948] Signal: Segmentation fault (11)
> [ubuntu:02948] Signal code: Address not mapped (1)
> [ubuntu:02948] Failing at address: (nil)
> [ubuntu:02948] [ 0] [0x792410]
> [ubuntu:02948] [ 1] ./exmpi_2(main+0x1f6) [0x8048d2a]
> [ubuntu:02948] [ 2]
> /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6) [0x126bd6]
> [ubuntu:02948] [ 3] ./exmpi_2() [0x8048aa1]
> [ubuntu:02948] *** End of error message ***
> --------------------------------------------------------------------------
> mpirun noticed that process rank 0 with PID 2948 on node ubuntu exited
> on signal 11 (Segmentation fault).
> --------------------------------------------------------------------------
>
> ____________________________________________________________________________
> Here is the input 2.pgm image :
> http://orion.math.iastate.edu/burkardt/data/pgm/balloons.pgm
>
> TQ for your help.
> <pgmmpi.tar.gz>_______________________________________________
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-- 
Jeff Squyres
jsquyres_at_[hidden]
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