That is perfectly valid. The MPI processes that make up the group are all part of comm world. I would file a bug with Intel MPI.
-Nathan > On Apr 2, 2019, at 7:11 AM, Stella Paronuzzi <stella.paronu...@gmail.com> > wrote: > > Good afternoon, I am attaching a simple fortran code that: > calls the MPI_INIT > duplicates the global communicator, via MPI_COMM_DUP > creates a group with half of processes of the global communicator, via > MPI_COMM_GROUP > finally from this group creates a new communicator via MPI_COMM_CREATE_GROUP > This last call is done using as a first argument MPI_COMM_WORLD instead of > the duplicated communicator used for creating the group. > With the intel MPI (ifort version 19.0.2.187, but also older) this generates > a seg fault, while using openMPI it doesn't. > > Uncommenting line 18 and commenting line 19 works fine with both. > Now, looking at the documentation, it seems like this code shouldn't work > after all, because the > > "MPI_COMM_DUP creates a new communicator over the same group as comm but with > a new context" > > and so it should't be possible to use the MPI_COMM_WORLD as a first argument > of the create MPI_COMM_CREATE_GROUP. > > What do you think? In the beginning I was thinking about a bug in the intel > MPI, but now I'm simply a bit confused ... > > Thank you in advance for the help > > Stella > > > > > > <mpi_comm_create_group.F90> > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/users
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