[Mpi-comments] is MPI_Igather thread-safe?

[Jonas Thies]

Dear MPI forum,

I posted a technical question on StackOverflow and was advised to ask it 
in this mailing list.

The original post is here: 
https://stackoverflow.com/questions/70697604/is-mpi-igather-thread-safe

In a nutshell, I am trying to call independent  MPI_Igathers in an 
OpenMP-parallel for-loop (after testing for MPI_THREAD_MULTIPLE),

and am getting a deadlock apparently caused by mismatched sends and 
receives, even in a very much stripped down example.

Any help on wether my code is not standard-conforming would be greatly 
appreciated. I attached two versions of the code for convenience, one of 
them is also in the StackOverflow post. The _v2 version does not 
deadlock but produces incorrect results when run with multiple MPI 
processes and multiple OpenMP thread per process.

Thanks and best wishes,

Jonas

-- 
*J. Thies*
Assistant Professor

TU Delft
Faculty Electrical Engineering, Mathematics and Computer Science
Institute of Applied Mathematics and High Performance Computing Center
Mekelweg 4
2628 CD Delft

T +31 15 27 XXXX
*J.Thies at tudelft.nl*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mpi-forum.org/pipermail/mpi-comments/attachments/20220115/71bc0e3b/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: igather_threaded_v2.cpp
Type: text/x-c++src
Size: 3078 bytes
Desc: not available
URL: <http://lists.mpi-forum.org/pipermail/mpi-comments/attachments/20220115/71bc0e3b/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: igather_threaded.cpp
Type: text/x-c++src
Size: 1355 bytes
Desc: not available
URL: <http://lists.mpi-forum.org/pipermail/mpi-comments/attachments/20220115/71bc0e3b/attachment-0001.bin>