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/*
* Copyright (C) by Argonne National Laboratory
* See COPYRIGHT in top-level directory
*/
#include "mpi.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "mpitest.h"
int main(int argc, char *argv[])
{
int size, rank, i, *excl;
MPI_Group world_group, even_group;
MPI_Comm even_comm;
MTest_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (size % 2) {
fprintf(stderr, "this program requires a multiple of 2 number of processes\n");
MPI_Abort(MPI_COMM_WORLD, 1);
}
excl = malloc((size / 2) * sizeof(int));
assert(excl);
/* exclude the odd ranks */
for (i = 0; i < size / 2; i++)
excl[i] = (2 * i) + 1;
/* Create some groups */
MPI_Comm_group(MPI_COMM_WORLD, &world_group);
MPI_Group_excl(world_group, size / 2, excl, &even_group);
MPI_Group_free(&world_group);
if (rank % 2 == 0) {
/* Even processes create a group for themselves */
MPI_Comm_create_group(MPI_COMM_WORLD, even_group, 0, &even_comm);
MPI_Barrier(even_comm);
MPI_Comm_free(&even_comm);
}
MPI_Group_free(&even_group);
MPI_Barrier(MPI_COMM_WORLD);
free(excl);
MTest_Finalize(0);
return 0;
}
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