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

Tue Jan 19 13:52:53 CST 2010

Hi,
 Rajeev, correct me if I got it wrong...
 On the client side when creating the intercommunicator you should specify the client_B intercommunicator with the client_A intracommunicator (MPI_Intercomm_create( comm_agg, 0,  pool_comm[1], 1, 12345  , &comm_aux ); ).
 Similarly on the server B side you should specify the client_B intercommunicator with the local communicator in B (MPI_Intercomm_create( comm_world, 0, comm_inter, 0, 12345 , &comm_aux ); 
).
 Let us know if it works.

Regards,
Jayesh
----- Original Message -----
From: "Francisco Javier García Blas" <fjblas at arcos.inf.uc3m.es>
To: jayesh at mcs.anl.gov
Cc: mpich-discuss at mcs.anl.gov
Sent: Tuesday, January 19, 2010 10:20:46 AM GMT -06:00 US/Canada Central
Subject: Re: [mpich-discuss] New communicator from connect/accept primitives

Hi Jayesh, 

I haven't problem with MPI_Intercomm_merge. I tried to merge using different directions successfully. I checked also the size of the new intracommunicator after merging and it is correct too (size 2). 

Additionally, yesterday I tried with MPI_Comm_spawn + MPI_Intercomm_create examples at testcase without problems. In these cases all the processes on the same group have same intercommunicators. However, in my case, I am doing something wrong when three processes call MPI_Intercomm_create over two remote groups. (AB intra, C inter). Arguments mistake maybe? 

As suggested Dave, I tried my example with the lasted stable version of MPICH2, with similar results. 

Thanks for all 

Regards 

El 19/01/2010, a las 16:22, jayesh at mcs.anl.gov escribió: 

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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-------------------------------------------------- 
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 
fjblas at inf.uc3m.es 
Phone:(+34) 916249118 
FAX: (+34) 916249129 
-------------------------------------------------- 