[Mpi-forum] MPI attribute callback behavior

[Bronis R. de Supinski]

Jeff:

Maybe I am not following. Wouldn't it be illegal based
on your original reasoning for B (it is still being
created so the delete is non-deterministic) and for A
(seems like a bad idea to modify, i.e., delete, what
you are in the middle of copying).

Bronis


On Mon, 25 Apr 2011, Jeff Squyres wrote:

> Here's a followup question: is it valid to call MPI_COMM_FREE on objects A or B when in a keyval copy callback with original object A and new object B?
>
> I can't decide whether the answer should be "yes" or "no"...
>
>
> On Apr 14, 2011, at 10:36 AM, Jeff Squyres wrote:
>
>> An issue recently came up within Open MPI as to what exactly you are allowed to do within an attribute callback (e.g., when a communicator is copied or deleted).
>>
>> From a standards point of view (i.e., regardless of implementation), here's a list that we came up with:
>>
>> 1. While in a keyval copy callback with original object A and new object B:
>> - Call MPI_Comm_get_attr on A: ok
>> - Call MPI_Comm_get_attr on B: erroneous
>>   (B is still being created, and therefore the get is non-deterministic)
>> - Call MPI_Comm_set_attr on A: erroneous
>>   (seems like a bad idea to modify what you're in the middle of copying)
>> - Call MPI_Comm_set_attr on B: erroneous (non-deterministive) if keyval exists on A, otherwise ok
>> - Call MPI_Comm_delete_attr on A: erroneous
>>   (seems like a bad idea to modify what you're in the middle of copying)
>> - Call MPI_Comm_delete_attr on B: erroneous (non-deterministic)
>>   (same as get_attr on B, above)
>> - Call MPI_Comm_create_keyval: ok
>> - Call MPI_Comm_free_keyval: ok
>>
>> 2. While in a keyval delete callback on object A:
>> - Call MPI_Comm_get_attr on A: erroneous
>>   (A is being deleted; that attribute may have already been deleted)
>> - Call MPI_Comm_set_attr on A: erroneous
>>   (why allow setting on an object that is being deleted?)
>> - Call MPI_Comm_delete_attr on A: erroneous
>>   (it's going to be deleted anyway)
>> - Call MPI_Comm_create_keyval: ok
>> - Call MPI_Comm_delete_keyval: ok
>>
>> Does anyone disagree with this list?
>>
>> Should we put some kind of list like this in MPI-3?  (I can work up a ticket if we think supporting text like this should be there)
>>
>> --
>> Jeff Squyres
>> jsquyres at cisco.com
>> For corporate legal information go to:
>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>
>
>
> -- 
> 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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