On Jul 27, 2019, at 10:43 PM, Gilles Gouaillardet via users
<users@lists.open-mpi.org> wrote:
>
> MPI_Isend() does not automatically frees the buffer after it sends the
> message.
> (it simply cannot do it since the buffer might be pointing to a global
> variable or to the stack).
Gilles is correct: MPI_Isend does not free the buffer. I was wondering if you
had somehow used that same buffer -- or some subset of that buffer -- in other
non-blocking MPI API calls, and freeing it triggered Bad Things because MPI was
still using (some of) that buffer because of other pending MPI requests.
> Can you please extract a reproducer from your program ?
Yes, please do this.
> Out of curiosity, what if you insert an (useless) MPI_Wait() like this ?
>
> MPI_Test(req, &flag, &status);
> if (flag){
> MPI_Wait(req, MPI_STATUS_IGNORE);
> free(buffer);
> }
That should be a no-op, because "req" should have been turned into
MPI_REQUEST_NULL if flag==true.
--
Jeff Squyres
jsquy...@cisco.com
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