[Mpi3-tools] Standardized MPI_COMM_WORLD rank environment variable?

George Bosilca bosilca at eecs.utk.edu
Tue Apr 24 17:30:58 CDT 2012

MCW is only meaningful in a static world. I'm not a tool expert, but I do not recall hearing about any tools that can cope with a dynamic environment where multiple MCW coexist in the context of the same application (and such application do exist).

What would be a "reasonable" unique identifier in this context?


On Apr 24, 2012, at 18:01 , Jeffrey Squyres wrote:

> On Apr 24, 2012, at 5:36 PM, Dries Kimpe wrote:
>>> Any kind of unique value would allow the tool to have a unique, safe filename.
>> What about a tmpnam for MPI then :-)
>> No need to bring details like rank->thread->process mapping into this if
>> all you want is a guaranteed unique filename among the MPI ranks of the
>> application.
> You do want it to be able to be mapped back to individual MPI (and/or OS) processes, though.  MCW rank is a pretty easy way to identify things.  
> If it weren't for this desire, PID would be sufficient.  But users find it to be a PITA to map PID back to whatever MCW rank it was.  That's why tools are looking for MPI-specific information that is meaningful to the user.
> FWIW: Also add Valgrind to the list of tools that Rayson mentioned (there's an option to suffix the valgrind output files with the MCW rank).
> -- 
> Jeff Squyres
> jsquyres at cisco.com
> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
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