[Mpi3-hybridpm] Fwd: Threading homeworking / next telecon

Pavan Balaji balaji at mcs.anl.gov
Sun Mar 24 20:40:54 CDT 2013

Let's use this:

International dial-in number: 1-719-234-7800
Domestic dial-in number: 1-888-850-4523
Participant Passcode: 314159

I'll add this information to the wiki.

 -- Pavan

On 03/24/2013 08:32 PM US Central Time, Rajeev Thakur wrote:
> A reminder that this telecon is scheduled for tomorrow at noon Eastern. What is the telecon number?
> Rajeev
> Begin forwarded message:
>> From: Rajeev Thakur <thakur at mcs.anl.gov>
>> Date: March 14, 2013 4:45:50 PM CDT
>> To: mpi3-hybridpm at lists.mpi-forum.org
>> Subject: Re: [Mpi3-hybridpm] Threading homeworking / next telecon
>> 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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Pavan Balaji

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