[mpich-discuss] mpi_comm_spawn problem

[Umit]

Hello All,

Thank you Rajeev for your e-mail.

My question is how to call mpi_spawn with a specific communicator. I dont
know how to call it with comm? and I am not sure if it is possible.

If you mean changeing the parameter "&intercomm" with "&comm" in
mpi_comm_spawn. It doesnt help. This parameter is not the name of calling
communicator. It is the intercommunicator between original group and the
newly spawned group.I have to change the name of original group.

I even tried it and it did not help. Please tell me if I am doing something
wrong. Here is *the new code and output:*

#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#define NUM_SPAWNS 4
    MPI_Comm comm, comm1;
    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 (i==2){
    MPI_Intercomm_merge( parentcomm, 1, &comm1 );
     goto jump; ///Here secondly spawned processes jump.
    }

    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 );
    }
    else
    {
    MPI_Intercomm_merge( parentcomm, 1, &comm );
    }
    argv[0] = "2";
    MPI_Comm_spawn( "/home/umit/Desktop/merge/./a.out", argv, np,
MPI_INFO_NULL, 0, MPI_COMM_WORLD, &comm, errcodes );
    MPI_Intercomm_merge( comm, 0, &comm1 );

    jump:
    MPI_Comm_rank (comm1, &rank);
    printf("I created at %d. call my rank is %d \n", i, rank);

    MPI_Finalize();
    return 0;
}

*output:
*umit at ubuntu:~/Desktop/merge$ mpirun -np 4 ./a.out 0
I created at 2. call my rank is 4
I created at 0. call my rank is 0
I created at 2. call my rank is 6
I created at 0. call my rank is 2
I created at 2. call my rank is 5
I created at 2. call my rank is 7
I created at 0. call my rank is 3
I created at 0. call my rank is 1
I created at 1. call my rank is 3
I created at 2. call my rank is 4
I created at 1. call my rank is 1
I created at 1. call my rank is 0
I created at 2. call my rank is 7
I created at 2. call my rank is 6
I created at 1. call my rank is 2
I created at 2. call my rank is 5
*
*Best Regards,






On 22 February 2012 19:22, Rajeev Thakur <thakur at mcs.anl.gov> wrote:

> You need to call the second spawn with comm instead of intercomm.
>
> On Feb 22, 2012, at 12:05 PM, Umit wrote:
>
> > 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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