Newsgroups: comp.parallel.mpi
From: Graham E Fagg <fagg@barney.cs.utk.edu>
Subject: Re: MPI Processes
Organization: Computer Science Dept, University of Tennessee, Knoxville
Date: Mon, 12 Feb 1996 20:34:20 -0500
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Message-ID: <Pine.SUN.3.91.960212203406.3904Y-100000@barney.cs.utk.edu>

Dear Greg,

 Can I ask a few more questions about this (having just read the Docs for  
version 6.0)?

Firstly is MPIL_Spawn callable from within an already running
application, i.e. one with its own context already defined?
Therefore the children will have a *different* COMM_WORLD?

Doesn't that mean that under the original definition (as in MPI-1) of an
inter-communicator, that the processes cannot then communicate as they
don't share COMM_WORLD (that was split into separate groups)?

And finally, in the example given on page 52 of the draft
MPI_Primer, for a fault tolerant system, it was stated that if a child died
then the inter-communicator would be freed. Even if you spawn a new
process it would have a different COMM_WORLD to the original lost process,
so how would the other processes from the original group communicate with
it (i.e. collective operations)? Would they have to use
inter-communicators (instead of intra-communicators) or would they recall
MPI_Init to somehow reform the group?
                                                                   O__
Graham.                                                            ,>/
==================================================================()=\()======
Graham E. Fagg      | Shared Memory, Message Passing & Groups |  PVM  MPI  VMD
Computer Science Dept |  104 Ayres Hall, Knoxville, TN 37996 | fagg@cs.utk.edu
University of Tennessee | Phone: +(423)974-3735  Fax: +(423)974-8296 \ SoftEng 
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