From: Michael Starkie <Starfire@LL.MIT.EDU>
Newsgroups: comp.parallel.mpi
Subject: Re: Dynamic process ranks and MPI ???
Date: Fri, 13 Nov 1998 15:36:41 -0500
Organization: MIT Lincoln Laboratory
Message-Id: <364C9858.B817DE5E@LL.MIT.EDU>
References: <3648B9B8.94272ACA@LL.MIT.EDU> <72ahq8$7ag$1@walter-fddi.cray.com>
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Eric Salo wrote:

> > Is there a mechanism I can use for dynamic ranks? In other words, I
> > don't know how many OTHER hello++ processes will be running at the time
> > I start a particular hello++ process.  I want each process to figure out
> > it's rank based on how many other hello++ processes happen to be running
> > at the time MPI::Init() is called!!.
>
> Sorry, you can't get there from here.


I see. That means that all MPI programs need to be spawned from the same
shell if they are to communicate.  This is a substantial restriction. What
about programs with a user-interface of some sort? Instances of programs with
a console interface for instance use dedicated shells and must run in the
foreground. From what you are saying, MPI does not appear to be a solution
for point to point communication between such programs.  If there is a way to
start MPI programs in seperate shells that allows them to communicate please
let me know.

--
Cordially,
Michael Starkie