[Mpi-forum] MPI_Comm_split_type question

[Guillaume Mercier]

Hi Jeff,

On 15/12/2016 18:48, Jeff Hammond wrote:
> The number of output communicators from MPI_Comm_split(_type) is always
> one.

Yes, obviously.

> Different ranks may get different outputs, but one cannot transfer
> a communicator object from one rank to another.

That's my issue actually.

> If you want to do how many total output communicators there are, you can
> perform an MPI_Allgather on the color arguments and see how many unique
> values there are.

I'm not sure about that: tae the case of MPI_Comm_split_type with
MPI_COMM_TYPE_SHARED. According to tha standards :"this type splits
the communicator into subcommunicators each of which can create  a 
shared memory region".
So, there is only one color, but several subcommunicators.
Or am I understanding this the wrong way?

Regards
Guillaume