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Subject: Re: [OMPI users] Problem with MPI_Barrier (Inter-communicator)
From: Thatyene Louise Alves de Souza Ramos (thatyene_at_[hidden])
Date: 2012-04-04 16:09:19


Hi Edgar, thank you for the response.

Unfortunately, I've tried with and without this option. In both the result
was the same... =(

On Wed, Apr 4, 2012 at 5:04 PM, Edgar Gabriel <gabriel_at_[hidden]> wrote:

> did you try to start the program with the --mca coll ^inter switch that
> I mentioned? Collective dup for intercommunicators should work, its
> probably again the bcast over a communicator of size 1 that is causing
> the hang, and you could avoid it with the flag that I mentioned above.
>
> Also, if you could attach your test code, that would help in hunting
> things down.
>
> Thanks
> Edgar
>
> On 4/4/2012 2:18 PM, Thatyene Louise Alves de Souza Ramos wrote:
> > Hi there.
> >
> > I've made some tests related to the problem reported by Rodrigo. And I
> > think, I'd rather be wrong, that /collective calls like Create and Dup
> > do not work with Inter communicators. I've try this in the client group:/
> >
> > *MPI::Intercomm tmp_inter_comm;*
> > *
> > *
> > *tmp_inter_comm = server_comm.Create (server_comm.Get_group().Excl(1,
> > &rank));*
> > *
> > *
> > *if(server_comm.Get_rank() != rank)*
> > *server_comm = tmp_inter_comm.Dup();*
> > *else*
> > *server_comm = MPI::COMM_NULL;*
> > *
> > *
> > The server_comm is the original inter communicator with the server group.
> >
> > I've noticed that the program hangs in the Dup call. It seems that the
> > tmp_inter_comm created without one process still has this process,
> > because the other processes are waiting for it call the Dup too.
> >
> > What do you think?
> >
> > On Wed, Mar 28, 2012 at 6:03 PM, Edgar Gabriel <gabriel_at_[hidden]
> > <mailto:gabriel_at_[hidden]>> wrote:
> >
> > it just uses a different algorithm which avoids the bcast on a
> > communicator of 1 (which is causing the problem here).
> >
> > Thanks
> > Edgar
> >
> > On 3/28/2012 12:08 PM, Rodrigo Oliveira wrote:
> > > Hi Edgar,
> > >
> > > I tested the execution of my code using the option -mca coll
> ^inter as
> > > you suggested and the program worked fine, even when I use 1 server
> > > instance.
> > >
> > > What is the modification caused by this parameter? I did not find
> an
> > > explanation about the utilization of the module coll inter.
> > >
> > > Thanks a lot for your attention and for the solution.
> > >
> > > Best regards,
> > >
> > > Rodrigo Oliveira
> > >
> > > On Tue, Mar 27, 2012 at 1:10 PM, Rodrigo Oliveira
> > > <rsilva.oliveira_at_[hidden] <mailto:rsilva.oliveira_at_[hidden]>
> > <mailto:rsilva.oliveira_at_[hidden]
> > <mailto:rsilva.oliveira_at_[hidden]>>> wrote:
> > >
> > >
> > > Hi Edgar.
> > >
> > > Thanks for the response. I just did not understand why the
> Barrier
> > > works before I remove one of the client processes.
> > >
> > > I tryed it with 1 server and 3 clients and it worked properly.
> > After
> > > I removed 1 of the clients, it stops working. So, the removal
> is
> > > affecting the functionality of Barrier, I guess.
> > >
> > > Anyone has an idea?
> > >
> > >
> > > On Mon, Mar 26, 2012 at 12:34 PM, Edgar Gabriel
> > <gabriel_at_[hidden] <mailto:gabriel_at_[hidden]>
> > > <mailto:gabriel_at_[hidden] <mailto:gabriel_at_[hidden]>>> wrote:
> > >
> > > I do not recall on what the agreement was on how to treat
> > the size=1
> > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > users mailing list
> > > users_at_[hidden] <mailto:users_at_[hidden]>
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
> > _______________________________________________
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> > users_at_[hidden] <mailto: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
> Associate 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
>
>
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