[Mpi3-hybridpm] Threading homeworking / next telecon

[Jeff Hammond]

I finally wrote up another ticket that was my attempt at a more
holistic proposal for thread-safety.  It's a bit raw, so please try to
extract the essence of it before poking at specific flaws.

https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/373

Jeff

On Mon, Mar 25, 2013 at 11:18 AM, Jeff Hammond <jhammond at alcf.anl.gov> wrote:
> In case people aren't on the call or didn't hear me clearly,
> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/371 is related to
> the two-faced issue of threads.
>
> Best,
>
> Jeff
>
> On Thu, Mar 14, 2013 at 4:45 PM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
>> 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.
>>
>> Rajeev
>>
>> 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
>>> MPI_THREAD_MULTIPLE, but MPI_THREAD_MULTIPLE's support is slow in
>>> 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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>>> Mpi3-hybridpm at lists.mpi-forum.org
>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-hybridpm
>>
>>
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>
>
>
> --
> Jeff Hammond
> Argonne Leadership Computing Facility
> University of Chicago Computation Institute
> jhammond at alcf.anl.gov / (630) 252-5381
> http://www.linkedin.com/in/jeffhammond
> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond



-- 
Jeff Hammond
Argonne Leadership Computing Facility
University of Chicago Computation Institute
jhammond at alcf.anl.gov / (630) 252-5381
http://www.linkedin.com/in/jeffhammond
https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond