[mpich-discuss] mpi_comm_spawn problem

[Umit]

Hello All,


I am running a mpi program with 4 processes and I am spawning 4 more
processes and adding them in a new intracommunicator with
mpi_intercomm_merge and having a intracommunicator with 8 processes. I am
successful until this point.

And then I want to call with these 8 processes 4 new processes and add them
in a new communicator and get 12 processes in my intracommunicator. But I
couldn’t spawn the new processes with these 8 processes.

Spawned processes and other processes are calling mpi_comm_spawn
separately. At first 4 processes are calling mpi_comm_spawn and then first
spawned processes are calling mpi_comm_spawn and I am getting two
intracommunicatiors each with 8 processes.

How can I make mpi_comm_spawn to call the new processes with new crated
intracommunicator? Is this possible?


Here is my code and the output of my program:


*Code:*

#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <stdint.h>



#define NUM_SPAWNS 4

    MPI_Comm comm;

    MPI_Comm parentcomm, intercomm;

    int np = NUM_SPAWNS;

    int errcodes[4];

    char argv[1];

    int rank;

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

{

    MPI_Init( &argc, &argv );

    MPI_Comm_get_parent( &parentcomm );

    int i = atoi(argv[1]);

    if (parentcomm == MPI_COMM_NULL)

    {

       argv[0] = "1";

        MPI_Comm_spawn( "/home/umit/Desktop/merge/./a.out", argv, np,
MPI_INFO_NULL, 0, MPI_COMM_WORLD, &intercomm, errcodes );

                MPI_Intercomm_merge( intercomm, 0, &comm );

                MPI_Comm_rank (comm, &rank);

                printf("I am not spawned my rank is %d \n", rank);

    }

    else

    {

                MPI_Intercomm_merge( parentcomm, 1, &comm );

                MPI_Comm_rank (comm, &rank);

                printf("I am spawned at %d. call my rank is %d \n", i,
rank);



                if (i==2) goto jump; ///Here secondly spawned processes
jump.

    }

    argv[0] = "2";

    MPI_Comm_spawn( "/home/umit/Desktop/merge/./a.out", argv, np,
MPI_INFO_NULL, 0, MPI_COMM_WORLD, &intercomm, errcodes );

    MPI_Intercomm_merge( intercomm, 0, &comm );

    MPI_Comm_rank (comm, &rank);

    jump:

    MPI_Finalize();

    return 0;

}



*Output is:
*

umit at ubuntu:~/Desktop/merge$ mpirun -np 4 ./a.out 0

I am spawned at 1. call my rank is 7

I am not spawned my rank is 3

I am spawned at 1. call my rank is 5

I am not spawned my rank is 1

I am spawned at 1. call my rank is 4

I am not spawned my rank is 2

I am spawned at 1. call my rank is 6

I am not spawned my rank is 0

I am spawned at 2. call my rank is 4

I am spawned at 2. call my rank is 6

I am spawned at 2. call my rank is 7

I am spawned at 2. call my rank is 5

I am spawned at 2. call my rank is 5

I am spawned at 2. call my rank is 4

I am spawned at 2. call my rank is 6

I am spawned at 2. call my rank is 7




Best Regards,
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