Greetings Jacob; sorry for the slow reply.
This is pretty subtle, but I think that your test is incorrect (I
remember arguing about this a long time ago and eventually having
another OMPI developer prove me wrong! :-) ).
1. You're setting MPI_ERRORS_RETURN, which, if you're using the C++
bindings, means you won't be able to see if an error occurs because
they don't return the int error codes.
2. The MPI_ERROR field in the status is specifically *not* set for
MPI_TEST and MPI_WAIT. It *is* set for the multi-test/wait functions
(e.g., MPI_TESTANY, MPI_WAITALL). MPI-2.1 p52:44-48 says:
"Error codes belonging to the error class MPI_ERR_IN_STATUS should be
returned only by the MPI completion functions that take arrays of
MPI_STATUS. For the functions MPI_TEST, MPI_TESTANY, MPI_WAIT, and
MPI_WAITANY, which return a single MPI_STATUS value, the normal MPI
error return process should be used (not the MPI_ERROR field in the
MPI_STATUS argument)."
So I think you need to use MPI::ERRORS_THROW_EXCEPTIONS to catch the
error in this case, or look at the return value from the C binding for
MPI_WAIT.
On May 10, 2009, at 5:51 AM, Katz, Jacob wrote:
Hi,
While trying error-related functionality of OMPI, I came across a
situation where when I use MPI_ERRORS_RETURN error handler, the
errors do not come out correctly from WAIT calls.
The program below correctly terminates with a fatal “message
truncated” error, but when the line setting the error handler to
MPI_ERRORS_RETURN is uncommented, it silently completes. I expected
the print out that checks the status after WAIT call to be executed,
but it wasn’t.
The issue didn’t happen when using blocking recv.
A bug or my incorrect usage?
Thanks!
// mpic++ -o test test.cpp
// mpirun -np2 ./test
#include "mpi.h"
#include <iostream>
using namespace std;
int main (int argc, char *argv[])
{
int rank;
char buf[100] = "hmmmm";
MPI::Status stat;
MPI::Init(argc, argv);
rank = MPI::COMM_WORLD.Get_rank();
// MPI::COMM_WORLD.Set_errhandler(MPI::ERRORS_RETURN);
if (rank == 0)
{
MPI::Request r = MPI::COMM_WORLD.Irecv(buf, 1, MPI_CHAR,
MPI::ANY_SOURCE, MPI::ANY_TAG);
r.Wait(stat);
if (stat.Get_error() != MPI::SUCCESS)
{
cout << "0: Error during recv" << endl;
}
}
else
{
MPI::COMM_WORLD.Send(buf, 2, MPI_CHAR, 0, 0);
}
MPI::Finalize();
return (0);
}
--------------------------------
Jacob M. Katz | jacob.k...@intel.com | Work: +972-4-865-5726 | iNet:
(8)-465-5726
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