At the present, the MPI-IO chapter says very little about what happens
when mixed collective operations are interleaved for the same file handle.
Here's a proposal to make the semantics well-defined. Since this can apply
to both file manipulation functions as well as data access functions, it
should probably be addressed in a new section on collective operations.
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PROPOSED TEXT:
Interleaving Collective Operations
Collective file operations are subject to the same semantics as collective
communication operations. Correct programs must issue collective file
operations so that deadlock will not occur. For a complete discussion of
interleaved collective operations, please refer to the semantics set forth
in the MPI Reference book(1), section 4.13.
Note that non-collective operations may be interleaved with collective
functions.
Multiple collective calls on different open file handles for the same file
is ?????? [note: this would work for our implementation]
Advice To Users:
[this assumes the technique in the above paragraph is not erroneous]
Consider opening the same file multiple times if you
find that you have need for multiple interleaved collective
operations to the same file.
End Advice To Users.
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(1) Marc Snir, Steve W. Otto, Steven Huss-Lederman, David W. Walker,
Jack Dongarra. MPI: The Complete Reference. MIT Press, 1996.