Why do we even dup the incoming communicator? Why not just assign it
directly to COMM_WORLD and CommWorld?
Is it just the "right" thing to do? Or is there really some reason for it?
Derek
On Thu, Apr 4, 2013 at 3:28 PM, Derek Gaston <fried...@gmail.com> wrote:
> Well... it has to do with the craziness of me swapping and unswapping MPI
> communicators to get libMesh to work on sub-communicators ;-)
>
> When I swap on one processor it sets both COMM_WORLD and CommWorld to the
> sub-communicator. When I swap back it sets them both to what COMM_WORLD
> was before the swap... so on any processor that swapped and swapped back
> COMM_WORLD would match CommWorld.
>
> If any processor didn't do any sub-solve then it won't swap at all... and
> so it has a mismatched COMM_WORLD and CommWorld.... so now the CommWorlds
> on processors that swapped won't match the CommWorlds on processors that
> don't swap..... and the next thing done using CommWorld will hang.
>
> Thoroughly confused? This is exactly why Ben's branch is so damn
> important ;-)
>
> Derek
>
>
> On Thu, Apr 4, 2013 at 3:17 PM, Roy Stogner <royst...@ices.utexas.edu>wrote:
>
>>
>> On Thu, 4 Apr 2013, Derek Gaston wrote:
>>
>> This has actually caused a bug that I've been trying to track down...
>>> just switching that last line to:
>>>
>>> Parallel::Communicator_World = libMesh::COMM_WORLD;
>>>
>>
>> How'd that bug manifest? You had some processors trying to
>> participate in a communication via COMM_WORLD and others trying to
>> participate in the same communication via CommWorld?
>>
>> Go ahead and commit that fix to master...
>> ---
>> Roy
>
>
>
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