Rob Falgout <[email protected]> added the comment:

Is somebody actually having a problem with communicator conflicts right now?

I thought the reason for this thread was to reduce the number of communicators 
because of limits in MPI implementations.  Somebody has to reduce the 
Comm_create() and Comm_dup() calls.  We responded with one way to reduce the 
create() calls in BoomerAMG, but now you are asking us to put them back in by 
calling dup()?  I'm confused about what we are trying to achieve here now.

The reason I suggested that the user be responsible for calling dup() is 
twofold: 1) I don't think it is common for users to run hypre in parallel with 
other user code where both are using the same communicator (I'm not sure how 
this could even work without deadlocking since hypre calls are collective); 2) 
Making libraries lower down on the call stack be responsible for calling dup() 
seems less scalable than the other way around and more likely to increase the 
number of communicators used.

Anyway, I'm still confused about what we are trying to achieve so maybe 
somebody can try to summarize again?

-Rob

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hypre Issue Tracker <[email protected]>
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