[MPICH] Forking exisiting mpi processes

[Greg Lindahl]

On Wed, Sep 20, 2006 at 02:55:14PM +0100, James S Perrin wrote:

> 	In our particular case the parent is only used to fork a child 
> 	process on demand, it doesn't need to make any MPI calls itself and so the 
> forked child process "can" assume it's identity.

As a piece of practical advice, you'll probably find this works in
some MPIs, it works in more if the parent doesn't call MPI_INIT(), but
it won't work with all MPIs no matter what, as some intentionally
disable fork() or do odd things that break in the presence of
fork(). The standard is so open that implementers do all kinds of odd
things. And for all you know, the next release of software for
whatever hardware you've purchased will break your program.

-- greg