Newsgroups: comp.parallel.mpi
From: lederman@b125.super.org (Steve Huss-Lederman)
Subject: Re: Waiting only on last requestor between two procs
Organization: Supercomputing Research Center, Bowie MD, USA
Date: Thu, 26 Oct 1995 02:27:47 GMT
Message-ID: <LEDERMAN.95Oct25222747@b125.super.org>

The question was asked if it is ok to free a request if you know you
will never need it.  Section 3.7.3 of the MPI 1.1 document clearly
states that this is ok.  You use MPI_REQUEST_FREE to do this.  The
Rationale given is exactly such a situation where you know for other
reasons that the request has been satisfied.  The advice to users
warns that you cannot then check such a request and an error code may
not be sent back to the user since the request is gone.  It also says
to never do it on a receive (only send) since you cannot tell if a
recieve has occured.  However, it seems to me that you have an example
where the logic tells you that the first 3 receives have completed.  I
think the advice to users may have been too restrictive about
receives.

Steve

