Re: [OMPI users] Simple MPI_Comm_spawn program hangs

Prakash Velayutham Thu, 6 Dec 2007 00:09:23 -0500

Hi Edgar,

I changed the spawned program from /bin/hostname to a very simple MPIprogram as below. But now, the slave hangs right at MPI_Init line.What could the issue be?


slave.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "mpi.h"
#include <sys/types.h>     /* standard system types       */
#include <netinet/in.h>    /* Internet address structures */
#include <sys/socket.h>    /* socket interface functions  */
#include <netdb.h>         /* host to IP resolution       */

int gdb_var;
void
main(int argc, char **argv)
{
        int             tag = 0;
        int             my_rank;
        int             num_proc;
        MPI_Status      status;
        MPI_Comm        inter_comm;

        gdb_var = 0;
  char hostname[64];

   FILE *f;

        while (0 == gdb_var) sleep(5);
  gethostname(hostname, 64);

        MPI_Init(&argc, &argv);
        MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
        MPI_Comm_size(MPI_COMM_WORLD, &num_proc);

        MPI_Comm_get_parent(&inter_comm);

        MPI_Finalize();
        exit(0);
}

Thanks,
Prakash


On Dec 2, 2007, at 8:36 PM, Edgar Gabriel wrote:

MPI_Comm_spawn is tested nightly by the test our suites, so it should
definitely work...

Thanks
Edgar

Prakash Velayutham wrote:

Thanks Edgar. I did not know that. Really?

Anyways, you are sure, an MPI job will work as a spawned process
instead of "hostname"?

Thanks,
Prakash


On Dec 1, 2007, at 5:56 PM, Edgar Gabriel wrote:

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 yourmaster";

       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@bmi-xeon1-01:~/thesis/CS/Samples> ./master1
MASTER : spawning a slave ...
bmi-xeon1-01

Any ideas  why?

Thanks,
Prakash
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--
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
_______________________________________________
users mailing list
us...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/users


_______________________________________________
users mailing list
us...@open-mpi.org
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
_______________________________________________
users mailing list
us...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/users

Re: [OMPI users] Simple MPI_Comm_spawn program hangs

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