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Subject: Re: [OMPI users] MPI_Comm_split and intercommunicator - Problem
From: Rodrigo Silva Oliveira (rsilva_at_[hidden])
Date: 2012-01-27 14:00:34


Hy Jeff, thanks for replying.

Does it mean that you don't have it working properly yet? I read the thread
at the devel list where you addressed the problem and a possible solution,
but I was not able to find a conclusion about the problem.

I'm in trouble without this function. Probably I'll need to redesign all my
implementation to achieve what I need.

On Fri, Jan 27, 2012 at 2:35 PM, Jeff Squyres <jsquyres_at_[hidden]> wrote:

> Unfortunately, I think that this is a known problem with INTERCOMM_MERGE
> and COMM_SPAWN parents and children:
>
> https://svn.open-mpi.org/trac/ompi/ticket/2904
>
>
> On Jan 26, 2012, at 12:11 PM, Rodrigo Oliveira wrote:
>
> > Hi there, I tried to understand the behavior Thatyene said and I think
> is a bug in open mpi implementation.
> >
> > I do not know what exactly is happening because I am not an expert in
> ompi code, but I could see that when one process define its color as
> MPI_UNDEFINED, one of the processes on the inter-communicator blocks in the
> call to the function bellow:
> >
> > /* Step 3: set up the communicator */
> > /* --------------------------------------------------------- */
> > /* Create the communicator finally */
> > rc = ompi_comm_set ( &newcomp, /* new comm */
> > comm, /* old comm */
> > my_size, /* local_size */
> > lranks, /* local_ranks */
> > my_rsize, /* remote_size */
> > rranks, /* remote_ranks */
> > NULL, /* attrs */
> > comm->error_handler,/* error handler */
> > (pass_on_topo)?
> > (mca_base_component_t *)comm->c_topo_component:
> > NULL, /* topo component */
> > NULL, /* local group */
> > NULL /* remote group */
> > );
> >
> > This function is called inside ompi_comm_split, in the file
> ompi/communicator/comm.c
> >
> > Is there a solution for this problem in some revision? I insist in this
> problem because I need to use this function for a similar purpose.
> >
> > Any idea?
> >
> >
> > On Wed, Jan 25, 2012 at 4:50 PM, Thatyene Louise Alves de Souza Ramos <
> thatyene_at_[hidden]> wrote:
> > It seems the split is blocking when must return MPI_COMM_NULL, in the
> case I have one process with a color that does not exist in the other group
> or with the color = MPI_UNDEFINED.
> >
> > On Wed, Jan 25, 2012 at 4:28 PM, Rodrigo Oliveira <
> rsilva.oliveira_at_[hidden]> wrote:
> > Hi Thatyene,
> >
> > I took a look in your code and it seems to be logically correct. Maybe
> there is some problem when you call the split function having one client
> process with color = MPI_UNDEFINED. I understood you are trying to isolate
> one of the client process to do something applicable only to it, am I
> wrong? According to open mpi documentation, this function can be used to do
> that, but it is not working. Anyone have any idea about what can be?
> >
> > Best regards
> >
> > Rodrigo Oliveira
> >
> >
> > _______________________________________________
> > 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
>
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
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>
>
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