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

[Rajeev Thakur]

Why don't you call your client as A, servers as B and C, and follow the algorithm below exactly:

> * 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.

Rajeev

> -----Original Message-----
> From: mpich-discuss-bounces at mcs.anl.gov 
> [mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of 
> Francisco Javier García Blas
> Sent: Monday, January 18, 2010 10:26 AM
> To: mpich-discuss at mcs.anl.gov
> 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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