MPI_Comm_spawn

//Roland Schulz roland at utk dot edu
#include <stdio.h>
#include <mpi.h>
#include <unistd.h>

int main(int argc, char** argv)
{
    MPI_Init(&argc, &argv);
    MPI_Comm parent;
    MPI_Comm_get_parent(&parent);
    if (parent==MPI_COMM_NULL) /*this is the parent*/
    {
        MPI_Comm children;
        MPI_Comm_spawn(argv[0], MPI_ARGV_NULL, 2, MPI_INFO_NULL, 0, MPI_COMM_WORLD,
               &children, MPI_ERRCODES_IGNORE);
        printf("Parent done spawning\n");
        MPI_Comm_disconnect(&children);
        MPI_Finalize();
        printf("Parent finalized\n");
        //sleep(2);
    }
    else
    {
        MPI_Comm_disconnect(&parent);
        int rank,size;
        MPI_Comm_size(MPI_COMM_WORLD, &size);
        MPI_Comm_rank(MPI_COMM_WORLD, &rank);
        printf("Hi from %d of %d\n", rank, size);
        sleep(1);
        MPI_Finalize();
        printf("Child finalized\n");
    }
    return 0;
}