[mpich-discuss] MPI_Intercomm_create() for merging two spawned groups

[Carsten Clauss]

Dear Wesley,

Thank you very much for your quick response and the tips you gave me -- 
that really helped a lot!

With kind regards,
Carsten

PS Please feel free to add the code to the test suite.

On 09/26/2014 06:29 PM, Wesley Bland wrote:
> I believe that your code is correct. I’ve gone through it to simplify
> things a bit (attached) and see the same errors as you. That’s probably
> a bug in MPICH that needs to be fixed unless someone else comes along
> and says that for MPI_INTERCOMM_CREATE to work, all processes must be in
> the same peer_comm, which doesn’t seem to be what the standard says to
> me. I’ll create a ticket and add you as a CC so you can keep track of
> things.
>
> In the meantime, you can avoid this problem by using one of the other
> ways of setting up communication between two group of processes. You can
> use the connect/accept functions as per this ticket:
> http://trac.mpich.org/projects/mpich/ticket/495 or you can change the
> way you spawn processes to have all processes in MPI_COMM_WORLD be
> involved in spawning the new processes. I don’t know if that will
> actually work for your application, but it’s a stopgap measure while we
> fix this bug.
>
> Thanks,
> Wesley
>
>
>> On Sep 26, 2014, at 10:50 AM, Carsten Clauss <c.clauss at fz-juelich.de> wrote:
>>
>> Dear all,
>>
>> I have a code where two processes (forming the original MPI_COMM_WORLD) each spawn one additional child process (using MPI_COMM_SELF as spawning group).
>>
>> Now I want to create an intra-comm that covers all of these four processes.
>>
>> For doing so, I initially merge the two inter-comms resulting from the spawn calls into two new intra-comms (by using MPI_Intercomm_merge()).
>>
>> Then I create via MPI_intercomm_create() a new inter-comm that connects these two by using the original world communicator as peer-com.
>>
>> Finally, I merge the resulting inter-comm into the desired intra-comm.
>>
>> When using Open MPI, my code (it's derived from the MPICH test spaiccreate2.c, see attachment) works fine on my local machine.
>> However, when running it with MPICH-3.1.2, I get the following error message:
>>
>> PMPI_Intercomm_create(601).....: MPI_Intercomm_create(comm=0x84000006, local_leader=1, MPI_COMM_WORLD, remote_leader=1, tag=123, newintercomm=0x7fff8323ee3c) failed
>> MPIR_Intercomm_create_impl(258):
>> MPID_GPID_ToLpidArray(461).....: Internal MPI error: Unknown gpid (1809769587)0
>> Fatal error in PMPI_Intercomm_create: Internal MPI error!, error stack:
>> PMPI_Intercomm_create(601).....: MPI_Intercomm_create(comm=0x84000004, local_leader=1, MPI_COMM_WORLD, remote_leader=0, tag=123, newintercomm=0x7fff6e0b4c7c) failed
>> MPIR_Intercomm_create_impl(258):
>> MPID_GPID_ToLpidArray(461).....: Internal MPI error: Unknown gpid (1607388239)0
>>
>> Here are my questions:
>> 1) Is the above mentioned approach the right way to reach my goal?
>> 2) Is the semantics of the attached code MPI compliant?
>> 3) What is the reason for the error message when using MPICH?
>>
>> Thanks in advance and with kind regards,
>> Carsten
>>
>> --
>> Carsten Clauss
>>www.par-tec.com <http://www.par-tec.com>
>> _____________________________________
>> ParTec Cluster Competence Center GmbH
>>
>> Possartstrasse 20
>> D-81679 Muenchen
>>
>> Geschäftsführer RA. Dipl.-Ing. Bernhard Frohwitter Eingetragen beim
>> Amtsgericht München HRB 151545 Steuer-Nr. 08/32305, Ust-ID DE235527064
>> <spaiccreate3.c>_______________________________________________
>> discuss mailing list     discuss at mpich.org
>> To manage subscription options or unsubscribe:
>>https://lists.mpich.org/mailman/listinfo/discuss
>
> _______________________________________________
> discuss mailing list     discuss at mpich.org
> To manage subscription options or unsubscribe:
> https://lists.mpich.org/mailman/listinfo/discuss

-- 
Carsten Clauss
www.par-tec.com
_____________________________________
ParTec Cluster Competence Center GmbH

Possartstrasse 20
D-81679 Muenchen

Geschäftsführer RA. Dipl.-Ing. Bernhard Frohwitter Eingetragen beim
Amtsgericht München HRB 151545 Steuer-Nr. 08/32305, Ust-ID DE235527064
_______________________________________________
discuss mailing list     discuss at mpich.org
To manage subscription options or unsubscribe:
https://lists.mpich.org/mailman/listinfo/discuss