source: CIVL/examples/mpi/simple/basic-deadlock-comm_dup.c

/* -*- Mode: C; -*- */
/* Creator: Bronis R. de Supinski (bronis@llnl.gov) Fri Mar  17 2000 */
/* no-error.c -- do some MPI calls without any errors */

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

#define buf_size 128

int
main (int argc, char **argv)
{
  int nprocs = -1;
  int rank = -1;
  char processor_name[128];
  int namelen = 128;
  int buf0[buf_size];
  int buf1[buf_size];
  MPI_Status status;
  MPI_Comm comm;

  /* init */
  MPI_Init (&argc, &argv);
  MPI_Comm_size (MPI_COMM_WORLD, &nprocs);
  MPI_Comm_rank (MPI_COMM_WORLD, &rank);
  MPI_Get_processor_name (processor_name, &namelen);
  //  printf ("(%d) is alive on %s\n", rank, processor_name);
  fflush (stdout);

  MPI_Barrier (MPI_COMM_WORLD);

  if (nprocs < 2) {
    printf ("not enough tasks\n");
  }
  else {
    MPI_Comm_dup (MPI_COMM_WORLD, &comm);
    
    if (rank == 0) {
      //  memset (buf0, 0, buf_size);

      MPI_Recv (buf1, buf_size, MPI_INT, 1, 0, comm, &status);
      
      MPI_Send (buf0, buf_size, MPI_INT, 1, 0, comm);
    }
    else if (rank == 1) {
      //  memset (buf1, 1, buf_size);

      MPI_Recv (buf0, buf_size, MPI_INT, 0, 0, comm, &status);

      MPI_Send (buf1, buf_size, MPI_INT, 0, 0, comm);
    }

    MPI_Comm_free (&comm);
  }

  MPI_Barrier (MPI_COMM_WORLD);

  MPI_Finalize ();
  printf ("(%d) Finished normally\n", rank);
}

/* EOF */