Gilles,
Ok, very nice!
When I excute
do rank=1,3
call MPI_Comm_spawn('hello_world','
',5,MPI_INFO_NULL,rank,MPI_COMM_WORLD,my_intercomm,MPI_ERRCODES_IGNORE,status)
enddo
I do get 15 instances of the 'hello_world' app running: 5 for each parent
rank 1, 2 and 3.
Thanks a lot, Gilles.
Best regargs,
Alex
2014-12-12 1:32 GMT-02:00 Gilles Gouaillardet <gilles.gouaillar...@iferc.org
>:
>
> Alex,
>
> just ask MPI_Comm_spawn to start (up to) 5 tasks via the maxprocs
> parameter :
>
> int MPI_Comm_spawn(char *command, char *argv[], int maxprocs,
> MPI_Info info,
> int root, MPI_Comm comm, MPI_Comm *intercomm,
> int array_of_errcodes[])
>
> INPUT PARAMETERS
> maxprocs
> - maximum number of processes to start (integer, significant
> only at root)
>
> Cheers,
>
> Gilles
>
>
> On 2014/12/12 12:23, Alex A. Schmidt wrote:
>
> Hello Gilles,
>
> Thanks for your reply. The "env -i PATH=..." stuff seems to work!!!
>
> call system("sh -c 'env -i PATH=/usr/lib64/openmpi/bin:/bin mpirun -n 2
> hello_world' ")
>
> did produce the expected result with a simple openmi "hello_world" code I
> wrote.
>
> I might be harder though with the real third party app I have in mind. And
> I realize
> getting passed over a job scheduler with this approach might not work at
> all...
>
> I have looked at the MPI_Comm_spawn call but I failed to understand how it
> could help here. For instance, can I use it to launch an mpi app with the
> option "-n 5" ?
>
> Alex
>
> 2014-12-12 0:36 GMT-02:00 Gilles Gouaillardet <gilles.gouaillar...@iferc.org
>
> :
>
> Alex,
>
> can you try something like
> call system(sh -c 'env -i /.../mpirun -np 2 /.../app_name')
>
> -i start with an empty environment
> that being said, you might need to set a few environment variables
> manually :
> env -i PATH=/bin ...
>
> and that being also said, this "trick" could be just a bad idea :
> you might be using a scheduler, and if you empty the environment, the
> scheduler
> will not be aware of the "inside" run.
>
> on top of that, invoking system might fail depending on the interconnect
> you use.
>
> Bottom line, i believe Ralph's reply is still valid, even if five years
> have passed :
> changing your workflow, or using MPI_Comm_spawn is a much better approach.
>
> Cheers,
>
> Gilles
>
> On 2014/12/12 11:22, Alex A. Schmidt wrote:
>
> Dear OpenMPI users,
>
> Regarding to this previous
> post<http://www.open-mpi.org/community/lists/users/2009/06/9560.php>
> <http://www.open-mpi.org/community/lists/users/2009/06/9560.php>
> <http://www.open-mpi.org/community/lists/users/2009/06/9560.php>
> <http://www.open-mpi.org/community/lists/users/2009/06/9560.php> from 2009,
> I wonder if the reply
> from Ralph Castain is still valid. My need is similar but quite simpler:
> to make a system call from an openmpi fortran application to run a
> third party openmpi application. I don't need to exchange mpi messages
> with the application. I just need to read the resulting output file
> generated
> by it. I have tried to do the following system call from my fortran openmpi
> code:
>
> call system("sh -c 'mpirun -n 2 app_name")
>
> but I get
>
> **********************************************************
>
> Open MPI does not support recursive calls of mpirun
>
> **********************************************************
>
> Is there a way to make this work?
>
> Best regards,
>
> Alex
>
>
>
>
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