From: dhumphrey@acm.org
Newsgroups: comp.parallel.mpi
Subject: MPI_Send doesn't seem to be sending
Date: Fri, 11 Jun 1999 21:07:29 GMT
Organization: Deja.com - Share what you know. Learn what you don't.
Message-Id: <7jrtqa$q2r$1@nnrp1.deja.com>
Xref: ukc comp.parallel.mpi:5183


While working on a new application, I've run into a problem for which
I've run out of ideas on how to analyze.  In a relatively simple test
scenario of a master and a single slave, the master never sees a
MPI_Send that the slave is sending.  I'm using the Win32 implementation
from dei.uc.pt.

After the master successfully passes several messages to the slave, the
slave tries to send a message containing results to the master with the
following function calls:

MPI_Send(&ncols,1,MPI_INT,0,111,MPI_COMM_WORLD);
MPI_Send(&opts
[3*ncols],7*ncols,MPI_DOUBLE,0,BGI_PUTCOMPS,MPI_COMM_WORLD);

The master never seems to see any of these messages.  When I use
MPI_Iprobe in the master to check for any kind of message from any
slave with:

for ( int n=0; n<10; n++ ) {
  MPI_Iprobe(MPI_ANY_SOURCE,MPI_ANY_TAG,MPI_COMM_WORLD,&flag,&status);
  printf ("MPI_Iprobe returned flag = %d\n",flag);
  Sleep(1000);
}

flag is always zero.  Does anyone out there have any advice?

Thanks in advance.

David Humphrey
Manager, Software Development
Bell Geospace, Inc
www.bellgeo.com


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