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Subject: Re: [OMPI users] Simple MPI_Comm_spawn program hangs
From: Edgar Gabriel (gabriel_at_[hidden])
Date: 2007-12-02 20:36:55


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 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
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
> _______________________________________________
> 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