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Subject: Re: [OMPI users] Simple MPI_Comm_spawn program hangs
From: Edgar Gabriel (gabriel_at_[hidden])
Date: 2007-12-01 17:56:59


MPI_Comm_spawn has to build an intercommunicator with the child process
that it spawns. Thus, you can not spawn a non-MPI job such as
/bin/hostname, since the parent process waits for some messages from the
child process(es) in order to set up the intercommunicator.

Thanks
Edgar

Prakash Velayutham wrote:
> Hello,
>
> Open MPI 1.2.4
>
> I am trying to run a simple C program.
>
> ######################################################################################
>
> #include <string.h>
> #include <stdlib.h>
> #include <stdio.h>
> #include "mpi.h"
>
> void
> main(int argc, char **argv)
> {
>
> int tag = 0;
> int my_rank;
> int num_proc;
> char message_0[] = "hello slave, i'm your master";
> char message_1[50];
> char master_data[] = "slaves to work";
> int array_of_errcodes[10];
> int num;
> MPI_Status status;
> MPI_Comm inter_comm;
> MPI_Info info;
> int arr[1];
> int rc1;
>
> MPI_Init(&argc, &argv);
> MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
> MPI_Comm_size(MPI_COMM_WORLD, &num_proc);
>
> printf("MASTER : spawning a slave ... \n");
> rc1 = MPI_Comm_spawn("/bin/hostname", MPI_ARGV_NULL, 1,
> MPI_INFO_NULL, 0, MPI_COMM_WORLD, &inter_comm, arr);
>
> MPI_Finalize();
> exit(0);
> }
>
> ######################################################################################
>
>
> This program hangs as below:
>
> prakash_at_bmi-xeon1-01:~/thesis/CS/Samples> ./master1
> MASTER : spawning a slave ...
> bmi-xeon1-01
>
> Any ideas why?
>
> Thanks,
> Prakash
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users

-- 
Edgar Gabriel
Assistant Professor
Parallel Software Technologies Lab      http://pstl.cs.uh.edu
Department of Computer Science          University of Houston
Philip G. Hoffman Hall, Room 524        Houston, TX-77204, USA
Tel: +1 (713) 743-3857                  Fax: +1 (713) 743-3335