[Mpi3-hybridpm] Threading homeworking / next telecon

Rajeev Thakur thakur at mcs.anl.gov
Thu Mar 14 16:45:50 CDT 2013

The analysis of thread safety needs of MPI routines that Bill mentioned on Wed is available here: http://wiki.mpich.org/mpich/index.php/Thread_Safety . It is referenced in this paper, www.mcs.anl.gov/~thakur/papers/threads-parco.pdf.


On Mar 14, 2013, at 3:00 PM, Barrett, Brian W wrote:

> Hi all -
> As a reminder, there's a hybrid telecon on Monday, March 25th at 12:00pm
> EDT.  During the telcon, we'll be following up from the meeting about
> threading (notes below).  Before the meeting, we're supposed to think
> about a couple of different issues regarding threads and the MPI spec,
> including:
>  * which MPI functions have functionality / usability deficiencies if an
> MPI does not support MPI_THREAD_MULTIPLE
>  * which MPI functions have use cases which present threading issues in
> the presence of threads?
> Some notes from this week's working group meeting:
>  * Jeff H. brought up the fact that library initialization is impossible
> to do in a thread safe manner.  Query_thread, for example, may not be
> called from the non-main thread in MPI_THREAD_FUNNELED (or by two threads
> simultaneously in MPI_THREAD_SERIALIZED).
>  * The tools working group has some use cases where the Intialized / Init
> race condition is problematic
>  * Fab would like us to revive the generalized request discussion; it's a
> feature that lacks a significant amount of usability without
> expanding.
>  * Bill brought up the concern that the forum has the tendency to be
> two-faced about threads.  We talk about "just use a thread" when trying to
> solve a particular problem, then are reluctant to require threads as part
> of the model; we should figure out how to deal with that.
> Brian
> --
>  Brian W. Barrett
>  Scalable System Software Group
>  Sandia National Laboratories
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