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From: Brian Barrett (bbarrett_at_[hidden])
Date: 2007-07-28 13:22:36

On Jul 28, 2007, at 6:27 AM, Jeff Squyres wrote:

> On Jul 27, 2007, at 8:27 PM, Lisandro Dalcin wrote:
>> MPI_WIN_GET_GROUP returns a duplicate of the group of the
>> communicator
>> used to create the window. associated with win. The group is returned
>> in group.
>> Well, it seems OMPI (v1.2 svn) is not returning a duplicate,
>> comparing
>> the handles with == C operator gives true. Can you confirm this?
>> Should the word 'duplicate' be interpreted as 'a new reference to' ?
> I would tend to agree with this wording; I think we're doing the
> wrong thing.
> Brian -- what do you think?

In my opinion, we conform to the standard. We reference count the
group, it's incremented on call to MPI_WIN_GROUP, and you can safely
call MPI_GROUP_FREE on the group returned from MPI_WIN_GROUP. Groups
are essentially immutable, so there's no way I can think of that we
violate the MPI standard.

Others are, of course, free to disagree with me.


   Brian W. Barrett
   Networking Team, CCS-1
   Los Alamos National Laboratory