Newsgroups: comp.parallel.mpi
From: fbreg@cs.vu.nl (Breg F)
Subject: internal error on SP-2 MPI
Organization: Fac. Wiskunde & Informatica, VU, Amsterdam
Date: Tue, 23 Jul 1996 11:14:52 GMT
Message-ID: <Duztwt.AKx.0.-s@cs.vu.nl>

I'm writing a library, using MPI and threads on an IBM SP2. 
To do this I use only non-blocking MPI-functions and protect
them using mutexes, because the info-explorer tells me the 
MPI-library is not thread-safe. The operating system is
AIX 4.1.

I've constructed a blocking receive by constantly probing
for incoming messages, using MPI_Iprobe and explicitly
receiving one when one has arrived. I've created a thread,
using the pthreads library, which executes such a receive.
This program sometimes crashes with the following message :

ERROR: 0032-114 Internal error:
                      Internal error. in MPI_Iprobe, task 0

The same code executed by the main thread does not give any
problems. Is this message a result of using pthreads with
MPI? The info-explorer mentions the incompatibility between
POE and threads. I hoped to solve this using the mutexes.
Is there any way to make this construct work? I really need
the threads together with the MPI-communication.

Thanks for any help,

Fabian Breg.

