Hi,

I tried implementing the Example 3.17 from the MPI 3.0 specification document using as follows:

#include <assert.h>

#include <mpi.h>

#include <stdio.h>

int main(int argc, char *argv[]) {

  int myrank, size;

  MPI_Status status;

  MPI_Init(&argc, &argv );

  MPI_Comm_rank(MPI_COMM_WORLD, &myrank);

  MPI_Comm_size(MPI_COMM_WORLD, &size);

  assert(size == 3);

  if (myrank == 0) {

    /* code for process zero */

    int i = 1;

    MPI_Send(&i, 1, MPI_INTEGER, 2, 99, MPI_COMM_WORLD);

  }

  if (myrank == 1) {

    /* code for process one */

    double d = 3.14;

    MPI_Send(&d, 1, MPI_REAL, 2, 99, MPI_COMM_WORLD);

  }

  if (myrank == 2) {

    /* code for process two */

    for (int i = 0; i < 2; i++) {

      MPI_Probe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);

      printf("Probe matched %lld bytes from source %d.\n",

             status.count, status.MPI_SOURCE);

      if (status.MPI_SOURCE == 0) {

int i;

MPI_Recv(&i, 1, MPI_INTEGER, 0, 99, MPI_COMM_WORLD, &status);

printf("Received integer '%d' from %d.\n", i, status.MPI_SOURCE);

      } else {

double d;

MPI_Recv(&d, 1, MPI_REAL, 1, 99, MPI_COMM_WORLD, &status);

printf("Received real '%f' from %d.\n", d, status.MPI_SOURCE);

      }

    }

  }

  MPI_Finalize();

  return 0;

}

This example compiles without any warning with the MPICH-3.0.4 library. However, running:

$ mpiexec -n 3 ./example

leads to the following output:

Probe matched 4 bytes from source 1.

Received real '0.000000' from 1.

Probe matched 4 bytes from source 0.

Received integer '1' from 0.

Could someone please let me know what is the problem with my program? I failed to see a problem there. Thank you.

Best,

--Jiri Simsa