[Mpi-forum] [EXTERNAL] Wording in MPI standard

Pavan Balaji balaji at mcs.anl.gov
Tue Nov 27 08:23:46 CST 2012

On 11/27/2012 04:48 AM US Central Time, Jeff Hammond wrote:
> Is it explicitly defined anywhere that "foo has been started" means
> "MPI_I*foo has been called by the appropriate MPI rank" or "sufficient
> matching has occurred such that foo can proceed without additional
> explicit remote activity"?  Perhaps this text would be more clear if
> it were more pedantic in this respect, assuming either of my
> equivalences are correct.

I think this needs to be clarified -- I always tell people that it needs
to be matched (even though the standard says it should have "started" --
what does that mean, if matching has started, but not completed, is it
considered "started").

> As for language, while "should" isn't legally enforceable in the same
> way that "must" or "shall" are, the MPI standard is not a legally
> binding document and I don't think any MPI implementer wants to be
> known as the jerk that exploits this loophole to create a formally
> standard-compliant implementation that screws over users by violating
> the principle of least surprise in important use cases such as Scott's
> example.

I have to agree with Scott here -- "must" or "is required to be" is a
clearer way to describe it.

 -- Pavan

Pavan Balaji

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