Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] MPI_Comm_Spawn intercommunication
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-01-22 07:08:45


Try using MPI_COMM_REMOTE_SIZE to get the size of the remote group in an intercommunicator. MPI_COMM_SIZE returns the size of the local group.

On Jan 7, 2011, at 6:22 PM, Pierre Chanial wrote:

> Hello,
>
> When I run this code:
>
> program testcase
>
> use mpi
> implicit none
>
> integer :: rank, lsize, rsize, code
> integer :: intercomm
>
> call MPI_INIT(code)
>
> call MPI_COMM_GET_PARENT(intercomm, code)
> if (intercomm == MPI_COMM_NULL) then
> call MPI_COMM_SPAWN ("./testcase", MPI_ARGV_NULL, 1, MPI_INFO_NULL, &
> 0, MPI_COMM_WORLD, intercomm, MPI_ERRCODES_IGNORE, code)
> call MPI_COMM_RANK(MPI_COMM_WORLD, rank, code)
> call MPI_COMM_SIZE(MPI_COMM_WORLD, lsize, code)
> call MPI_COMM_SIZE(intercomm, rsize, code)
> if (rank == 0) then
> print *, 'from parent: local size is ', lsize
> print *, 'from parent: remote size is ', rsize
> end if
> else
> call MPI_COMM_SIZE(MPI_COMM_WORLD, lsize, code)
> call MPI_COMM_SIZE(intercomm, rsize, code)
> print *, 'from child: local size is ', lsize
> print *, 'from child: remote size is ', rsize
> end if
>
> call MPI_FINALIZE (code)
>
> end program testcase
>
> I get the following results with openmpi 1.4.1 and two processes:
> from parent: local size is 2
> from parent: remote size is 2
> from child: local size is 1
> from child: remote size is 1
>
> I would have expected:
> from parent: local size is 2
> from parent: remote size is 1
> from child: local size is 1
> from child: remote size is 2
>
> Could anyone tell me what's going on ? It's not a fortran issue, I can also replicate it using mpi4py.
> Probably related to the universe size: I haven't found a way to hand it to mpirun.
>
> Cheers,
> Pierre
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users

-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/