Dick, if I'm right, then 23.r is not similar. 23.r OK p183, lines 5-8. This advice to implementors on reference counts for groups should include MPI_COMM_GROUP as a routine that increments the reference count. I've put yours as 29.a in http://www.hlrs.de/mpi/mpi21/doc/MPI-2.1draft-2008-02-23-review.txt 23.r I made an OK, but for your 29.a I would recommend to go to MPI-2.2. Best regards Rolf On Mon, 7 Apr 2008 10:54:00 -0400 Richard Treumann <treumann_at_[hidden]> wrote:

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

Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden] High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530 University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832 Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)