[Mpi3-ft] MPI_Comm_validate_all

[Darius Buntinas]

MPI_Comm_validate_all, according to the proposal at [1], must "either complete successfully everywhere or return some error everywhere."  Is this possible to guarantee?  What about process failures during the call?  Consider the last message sent in the protocol.  If the process sending that message dies just before sending it, the receiver will not know whether to return success or failure.

I think that the best we can do is say that the outcount and list of collectively-detected dead processes will be the same at all processes where the call completed successfully.

Or is there a trick I'm missing?

Thanks,
-d

[1] https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/ft/run_through_stabilization#CollectiveValidationOperations