[Mpi3-ft] Transactional Messages

[Greg Bronevetsky]

>I've read the Transactional Messages proposal and I am a ittle confused
>here.  Is there a reason why we believe that message faults themselves
>should be handled by the application layer instead of the MPI library?
>Using the latter model allows one to reduce the error conditions
>perculated up to the user to revolve around loss of the actual
>connection to a process (or the actual process itself).

Actually, one aspect of the proposal is that I made sure not to 
define message faults at a low level. They may be any low-level 
problems that the implementation cannot efficiently deal with on its 
own and that are best represented to the application as message 
drops. One example of this may be process failures. Although we will 
probably want to define a special notification mechanism to expose 
those failures to the application, we will also need a way to expose 
the failures of any communication that involves the process. Another 
example may be simplified MPI implementations that do not have 
facilities for resending messages because the probability of an error 
is rather low and performance is too important. In fact, applications 
that can tolerate message drops may explicitly choose those MPI 
implementations for the performance gains.

Greg Bronevetsky
Post-Doctoral Researcher
1028 Building 451
Lawrence Livermore National Lab
(925) 424-5756
bronevetsky1 at llnl.gov