[mpich-discuss] Setting for max number of nonblocking messages?

[Halim Amer]

From your description, I don't see any reason why MPICH would hang if
the user code is correct.
Can you send us a small test code that reproduces this problem?

Halim
www.mcs.anl.gov/~aamer

On 11/3/17 10:27 AM, Adam Sylvester wrote:
> I have an application which runs 16 ranks, where there is a step in the
> processing where each rank does an MPI_Irecv() and MPI_Isend() with
> every other rank, then calls MPI_Waitall().  The code could likely be
> refactored to use an MPI_Alltoallv() instead, but that's not my point
> here as this portion of the code isn't a bottleneck.
> 
> I've previously been using Open MPI which has run this block of code
> thousands of times without issues.  I just switched over to MPICH 3.2
> (obviously recompiling my application) and it hangs in this block (there
> is MPI communication involving at least as much data movement earlier in
> the chain using a series of MPI_Ialltoallv() calls which completes
> without issue).  I need to reduce the number of ranks down to 2 for it
> to make it through the MPI_recv() / MPI_Isend() / MPI_Waitall() section.
> 
> I'm wondering if there's a setting for the max number of nonblocking
> messages that defaults to a low value for MPICH.  Or any other thoughts
> on what I could be running into?
> 
> Thanks.
> -Adam
> 
> 
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