[Mpi-22] Fw: Ticket #71: Add routine for registering callback when finalize occurs

Richard Treumann treumann at [hidden]
Mon Mar 30 13:53:04 CDT 2009


I should have said LIFO below.  The proposal is to have attribute deletion
callback occur in the reverse of the order in which they were placed.

I have no objection to making this part of the standard but do not think it
should be unique to MPI_COMM_SELF if we adopt it.

Dick Treumann  -  MPI Team
IBM Systems & Technology Group
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846         Fax (845) 433-8363

----- Forwarded by Richard Treumann/Poughkeepsie/IBM on 03/30/2009 02:49 PM
-----
                                                                                                                                      
  From:       Richard Treumann/Poughkeepsie/IBM_at_IBMUS                                                                                 
                                                                                                                                      
  To:         "MPI 2.2" <mpi-22_at_[hidden]>                                                                                  
                                                                                                                                      
  Date:       03/30/2009 10:12 AM                                                                                                     
                                                                                                                                      
  Subject:    Re: [Mpi-22] Ticket #71: Add routine for registering callback     when        finalize occurs                           
                                                                                                                                      

I understand that the immediate motive is associated with the use of
attribute delete callbacks that occur when MPI_COMM_SELF is freed at
MPI_FINALIZE.

That does not alter the fact that when MPI-2 imposed an implicit free of
MPI_COMM_SELF in MPI_FINALIZE to allow the use of attribute delete
functions for cleanup it involved a narrow extension of a general MPI
facility related to attributes and certain object types. To allow attribute
delete functions for all other communicators (etc) to occur in arbitrary
order while demanding that attribute delete for MPI_COMM_SELF have a
standards defined order is an inelegant hack (in my opinion). Freeing
MPI_COMM_SELF within MPI_FINALIZE was a relatively elegant hack because it
did not introduce inconsistency.

Add to that the probability that an MPI implementor is likely to use the
same algorithms for all attribute management rather than write special case
code for MPI_COMM_SELF leads me to argue that if a defined order for
attribute delete callbacks is adopted it should be adopted broadly to
maintain a consistent flavor across the standard.

If an existing MPI implementation is currently deleting in some other order
and an application happens to work on that MPI only because of that order,
that application is at least non-portable and probably should be considered
buggy. If (or when) the implementation adopts the fifo order for attribute
deletes on "user_comm" it would be clear that the implementation change had
not "broken the user".

A general mandate that attribute deletion callbacks on all object types
must occur in fifo order for an implementation to be MPI 2.2 compliant
should not break any "correct" MPI application and should not be noticeably
harder for implementors.

It will require tracking down all places in the standard that currently say
the order is arbitrary so it is harder to get all ducks in a row for the
ticket.

Dick Treumann - MPI Team
IBM Systems & Technology Group
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363

mpi-22-bounces_at_[hidden] wrote on 03/28/2009 11:57:19 PM:

> [image removed]
>
> Re: [Mpi-22] Ticket #71: Add routine for registering callback when
> finalize occurs
>
> Quincey Koziol
>
> to:
>
> mpi-22
>
> 03/30/2009 09:28 AM
>
> Sent by:
>
> mpi-22-bounces_at_[hidden]
>
> Please respond to "MPI 2.2"
>
>
> > Date: Thu, 26 Mar 2009 13:24:26 -0400
> > From: Richard Treumann <treumann_at_[hidden]>
> > Subject: Re: [Mpi-22] Ticket #71: Add routine for registering callback
> >    when   finalize occurs
> > To: "MPI 2.2" <mpi-22_at_[hidden]>
> > Message-ID:
> >    <OFE2F8673A.D3771BE2-
> > ON85257585.005F95BC-85257585.005F9F47_at_[hidden]>
> > Content-Type: text/plain; charset="us-ascii"
> >
> > Why would this be specific to MPI_COMM_SELF?  If this is the right
> > thing to
> > do, shouldn't it apply to attribute delete functions on all disposed
> > objects?
>
>    The ticket is oriented to what happens at MPI_Finalize, really, and
> not so much about MPI_COMM_SELF per se.  The attribute callback on
> MPI_COMM_SELF was just the accepted way in the standard to "have
> something happen" when MPI_Finalize was called.
>
>    Quincey
>
> > Dick Treumann  -  MPI Team
> > IBM Systems & Technology Group
> > Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
> > Tele (845) 433-7846         Fax (845) 433-8363
> >
> >
> > mpi-22-bounces_at_[hidden] wrote on 03/26/2009 12:50:40 PM:
> >
> >> [image removed]
> >>
> >> [Mpi-22] Ticket #71: Add routine for registering callback when
> >> finalize
> > occurs
> >>
> >> Quincey Koziol
> >>
> >> to:
> >>
> >> mpi-22
> >>
> >> 03/26/2009 12:54 PM:
> >>
> >> Sent by:
> >>
> >> mpi-22-bounces_at_[hidden]
> >>
> >> Please respond to "MPI 2.2"
> >>
> >> Hi all,
> >>  Could another two people review this ticket for specifying the order
> >> that attribute delete callbacks should be made:
> >>
> >> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/71
> >>
> >>  Thanks,
> >>     Quincey
> >>
> >> [attachment "smime.p7s" deleted by Richard Treumann/Poughkeepsie/
> >> IBM] _______________________________________________
> >> mpi-22 mailing list
> >> mpi-22_at_[hidden]
> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22
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> > End of mpi-22 Digest, Vol 12, Issue 26
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>
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