Newsgroups: comp.parallel.mpi
From: nils@cs.dartmouth.edu (Nils Nieuwejaar)
Subject: Re: MPI & SunOS 5.3 threads
Organization: Disco Frog, Inc.
Date: 16 Jun 1995 18:00:02 GMT
Message-ID: <NILS.95Jun16140002@sparrowhawk.dartmouth.edu>

Spyros Pollatos <sxp@dcs.ed.ac.uk> writes:

> I am developing an application using LAM 5.2 and SunOS 5.3
> threads. It seems to me that according to the ``MPI: A
> Message-Passing Interface Standard'' MPI should be
> thread-safe.

The standard was designed to make it possible for an implementation to
be thread safe, but it doesn't require that it be thread safe.

> However, nothing in the locally available LAM documentation mentions
> threads. Furthermore, as soon as two of my threads call LAM
> functions, everything just grinds to a halt.

MPICH also appears not to be thread safe, at least not with IBM's DCE
Threads (on AIX 3.2.5).  When using the ch_p4 device (or just p4
without MPI for that matter), any program that runs on 4 or more nodes
dies loudly (an endless stream of thread deadlock messages) as soon as
MPI_Init() is called.  When using the ch_eui device (on top of IBM's
MPL), it appears to hang silently (possibly deadlocked as with ch_p4,
but without the error messages?).

I keep meaning to work up a minimal example to forward to the MPICH
and p4 implementors...

