[mpich-discuss] New communicator from connect/accept primitives

[jayesh at mcs.anl.gov]

Hi,
 I haven't looked at your code yet. You can look at the testcase, testconnect.c (https://svn.mcs.anl.gov/repos/mpi/mpich2/trunk/test/mpi/manual/testconnect.c), in the MPICH2 test suite for a simple example on how to use connect/accept and intercomm_merge to create an intracommunicator.

-Jayesh

----- Original Message -----
From: "Francisco Javier García Blas" <fjblas at arcos.inf.uc3m.es>
To: mpich-discuss at mcs.anl.gov
Sent: Monday, January 18, 2010 10:26:08 AM GMT -06:00 US/Canada Central
Subject: Re: [mpich-discuss] New communicator from connect/accept primitives

Hello again,

In first place, thanks for response of Rajeev and Jayesh. Following 
Rajeev 's instruccion,  I implemented an basic example using 
connect/accept and intercomm_create/merge primitives. I am doing 
something wrong because when MPI_Intercomm_create is invoked, all the 
processes become blocked. I don't find the error, maybe it could be a 
bad numeration in local and remote communicator but I tried all the 
combinations.

I am using mpich2 1.0.5.

I attach the source code and a makefile.

Best regards

Rajeev Thakur escribió:
> You will need to use intercomm_merge but you have to merge them one 
> pair at a time. Example below from an old mail.
>  
> Rajeev
>  
>  
> If you have 3 intercommunicators AB_inter, AC_inter, and AD_inter, you 
> can merge them all into a single
> intercommunicator as follows:
>  
> * begin by doing an MPI_Intercomm_merge on AB_inter, resulting in an
> intracommunicator AB_intra.
>  
> * then create an intercommunicator between AB on one side and C on the 
> other
> by using MPI_Intercomm_create. Pass AB_intra as the local_comm on A and B,
> MPI_COMM_WORLD as the intracomm on C, and AC_inter as the peer_comm. This
> results in the intercommunicator AB_C_inter.
>  
> * then call MPI_Intercomm_merge on it to create the intracommunicator
> ABC_intra.
>  
> * then call MPI_Intercomm_create to create an intercommunicator 
> between ABC
> and D just as you did with AB and C above.
>  
> * Again do an intercomm_merge. This will give you an intracommunicator
> containing A, B, C, D.
>  
> * If you want an intercommunicator with A in one group and B,C,D in the
> other, as you would get with a single spawn of 3 processes, you have 
> to call
> MPI_Comm_split to split this single communicator into two
> intracommunicators, one containing A and the other containing B,C,D. Then
> call MPI_Intercomm_create to create the intercommunicator.
>
>     ------------------------------------------------------------------------
>     *From:* mpich-discuss-bounces at mcs.anl.gov
>     [mailto:mpich-discuss-bounces at mcs.anl.gov] *On Behalf Of
>     *Francisco Javier García Blas
>     *Sent:* Friday, January 15, 2010 11:09 AM
>     *To:* mpich-discuss at mcs.anl.gov
>     *Subject:* [mpich-discuss] New communicator from connect/accept
>     primitives
>
>     Hello all,
>
>     I wondering the possibility of get a new inter-comunicator from N
>     communicators, which are results from different calls of
>     mpi_comm_connect or mpi_comm_accept.
>
>     My initial solution was first,  to get the group of each
>     inter-communicator with mpi_comm_group, second, to join all the
>     groups into one bigger and finally, to create a new communicator
>     from the group with the mpi_comm_create primitive. 
>
>     Currently I am handling a pool of inter - communicators in order
>     to keep the functionality. However this idea is not suitable for
>     collective and MPI_ANY_SOURCE sends/recvs.
>
>     Exist another way to join all the inter-communicator into one?    
>
>     Any suggestion?
>
>     Best regards.
>
>
>
>
>     --------------------------------------------------
>     Francisco Javier García Blas
>     Computer Architecture, Communications and Systems Area.
>     Computer Science Department. UNIVERSIDAD CARLOS III DE MADRID
>     Avda. de la Universidad, 30
>     28911 Leganés (Madrid), SPAIN
>     e-mail: fjblas at arcos.inf.uc3m.es <mailto:fjblas at arcos.inf.uc3m.es>
>                   fjblas at inf.uc3m.es <mailto:fjblas at inf.uc3m.es>
>     Phone:(+34) 916249118
>     FAX: (+34) 916249129
>     --------------------------------------------------
>
> ------------------------------------------------------------------------
>
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