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/*
* Copyright (C) by Argonne National Laboratory
* See COPYRIGHT in top-level directory
*/
#include <stdio.h>
#include "mpi.h"
int main(int argc, char *argv[])
{
char str[10];
int err = 0, errcodes[256], rank, rank1, nprocs;
MPI_Comm intercomm1, intercomm2, intracomm;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
MPI_Comm_rank(MPI_COMM_WORLD, &rank1);
if (nprocs != 2) {
printf("Run this program with 2 processes\n");
MPI_Abort(MPI_COMM_WORLD, 1);
}
if (rank1 == 0) {
printf("Parents spawning 2 children...\n");
fflush(stdout);
}
err = MPI_Comm_spawn("spawn_merge_child1", MPI_ARGV_NULL, 2,
MPI_INFO_NULL, 1, MPI_COMM_WORLD, &intercomm1, errcodes);
if (err)
printf("Error in MPI_Comm_spawn\n");
if (rank1 == 0) {
printf("Parents and children merging to form new intracommunicator...\n");
fflush(stdout);
}
MPI_Intercomm_merge(intercomm1, 0, &intracomm);
if (rank1 == 0) {
printf("Merged parents spawning 2 more children and communicating with them...\n");
fflush(stdout);
}
err = MPI_Comm_spawn("spawn_merge_child2", MPI_ARGV_NULL, 2,
MPI_INFO_NULL, 2, intracomm, &intercomm2, errcodes);
if (err)
printf("Error in MPI_Comm_spawn\n");
MPI_Comm_rank(intercomm2, &rank);
if (rank == 2) {
err = MPI_Recv(str, 3, MPI_CHAR, 1, 0, intercomm2, MPI_STATUS_IGNORE);
printf("Parent received from child: %s\n", str);
fflush(stdout);
err = MPI_Send("bye", 4, MPI_CHAR, 1, 0, intercomm2);
}
MPI_Finalize();
return 0;
}
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