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Subject: [OMPI users] Open MPI job not joining up under TotalView.
From: Peter Thompson (peter.thompson_at_[hidden])
Date: 2011-07-12 15:12:01

I wonder if someone might have possible ideas to explore as to why this
program might not be working correctly under TotalView. Essentially a
user is running a very simple hello world like program that does this:

#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

int main(int argc, char **argv)
  MPI_Init( &argc, &argv );
  int rank, size;
  MPI_Comm_rank( MPI_COMM_WORLD, &rank );
  MPI_Comm_size( MPI_COMM_WORLD, &size );
  printf("rank = %d, size = %d\n", rank, size );
  exit( EXIT_SUCCESS );

When run under

mpirun -np 8 ./foo

It spits out 8 lines with ranks 0 through 7 and a size or 8. But when
run under TotalView, he sees 8 lines, all of rank 0, and size of 1. So
it looks like the processes never combine up when on his system under
TV. To make this a bit more interesting, when I run the same program
here, I do NOT see this separate behavior. The processes all join up
and everything looks okay. My machine, as his, is a Mac running the
10.6.8 Darwin. To try and keep this replicable, I just used the native
OpenMPI on Darwin. TotalView is started up with

totalview foo

and then Parallel is chosen from the Startup Parameters window, and Open
MPI and 8 processes are chosen. Any thoughts about why I might see one
8 process job, and he sees 8 single process jobs? Are there any hidden
debug flags I can use?