[mpi-21] Inconsistent error behavior of multiple completion routines

[William Gropp]

Rolf,

Answers inline below.

Bill

On Jan 28, 2008, at 11:33 AM, Rolf Rabenseifner wrote:

> Bill,
>
> please, can you specify more precisely:
>
> - Is your proposal necessary for MPI_Wait/Test_some/all
>   (but not for MPI_Wait/Test or MPI_Wait/Test_any)

That is correct.  It applies only if MPI_ERR_IN_STATUS may be  
returned by the routine; that is for MPI_{Wait,Test}_{some,all} .

> - Should it be inserted 4 times at the 4 routines, or can it be  
> done once
>   somewhere at errorhandling?

It is probably better to insert it once but have each affected  
routine clearly point at the one discussion.

> - should you substitute "valid communicators (including File  
> operations)"
>   by "valid communicators and file handles"?

Probably.

> - error handler on MPI_COMM_WORLD --> how is it for file handles?

This is tricky.  The idea is to use the error handler that is used  
when there is no other obvious error handler, and in the rest of MPI,  
that is MPI_COMM_WORLD.  If it is clear that the request is an MPI I/ 
O request, then the error handler on MPI_FILE_NULL should be invoked,  
to be consistent with the operations on files.

> - default for file handles is _MPI_ERRORS_RETURN!

Yes, but this should be ok.  For uses of these routines where all of   
the requests are MPI I/O requests, the error handler on the file  
object will be used.  If the parameters to the routine are bad (e.g.,  
a negative count), then the error handler on MPI_COMM_WORLD will be  
invoked.  That seems fine.

> and reply this on the mpi-21_at_[hidden] as a Ballot 4 issue (if  
> you want)
>
> I expect, it is the best to give this still valid topic from 2001
> back to the author of the topic :-)
>
> Thanks and best regards
> Rolf
> ___________________________________
> This is a inquity for detailed specification for MPI 2.1, Ballot 4.
>
> This is a follow up to:
>   Error handler for multiple completions
>   in http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi- 
> errata/index.html
> with mail discussion in
>   http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi- 
> errata/discuss/waitallerr/
> ___________________________________
>
> Best regards
> Rolf
>
>
>
> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
> High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
> University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
> Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
> Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)
>

William Gropp
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign





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