[Mpi-21] 2.1 cleanup or MPI 2.2?

[Richard Treumann]

In the description of MPI_COMM_FREE we presently give the following advise
to implementors.

A reference-count mechanism may be used: the reference count is
incremented by each call to \func{MPI\_COMM\_DUP}, and decremented by
each call to \func{MPI\_COMM\_FREE}.  The object is ultimately
deallocated when the count reaches zero.

I do not think it can ever be valid to implement MPI_COMM_DUP by simply
returning a new handle for an existing communicator object while bumping
its reference count because the output communicator must have a different
context than the original.  Assuming I have not missed something, it seems
this advise is nonsense.

Is removing this the kind of change that should go on the MPI 2.2 list?  I
will be surprised if anyone offers a rationale for keeping the advise but I
am also not quite comfortable that it fits within the "clean up" rules for
MPI 2.1 at this late stage.

Thoughts?

                 Dick

Dick Treumann  -  MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846         Fax (845) 433-8363





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