From octave-maintainers-request at bevo dot che dot wisc dot edu Thu Nov 21 11:31:11 2002
Subject: Re: Patching Octave-MPI
From: JD Cole <jdcole at san dot rr dot com>
To: andyj at splash dot princeton dot edu
CC: octave-maintainers at bevo dot che dot wisc dot edu
Date: Thu, 21 Nov 2002 09:41:43 -0800

Andy Jacobson wrote:

>>>>>>"Paul" == Paul Kienzle <pkienzle at jazz dot ncnr dot nist dot gov> writes:
>>>>>>            
>>>>>>
>
>    Paul> There are a variety of approaches to parallelism which have
>    Paul> been done in matlab m-files and mex-files.  E.g.,
>
>Alex Verstak raised an interesting point last year: he said that the
>MPI standard requires that MPI_Init() be fed the *original* argv and
>argc.  (Yes, it is arguably a silly requirement.)  With at least MPICH
>apparently, MPI_Init() would not work from a .oct file.  See:
>
>http://www.octave.org/mailing-lists/help-octave/2001/141
>
>Later however, Alex apparently did get it running:
>
>http://www.octave.org/mailing-lists/help-octave/2001/218
>
>So perhaps a .oct solution will work.
>
>Note however that the parallelized Matlab solutions all are guided by
>two facts: (1) they cannot modify the source code so the
>parallelization has to work via .mex/.m files, and (2) due to the cost
>of multiple Matlab licenses, there may be implicit assumptions about
>how many instances are running in a given MPI application.  There may
>be hidden performance issues.
>
>It should a pretty trivial matter to determine whether or not the user
>wants a parallel or traditional application when she starts octave.
>Perhaps something as simple as "octave --mpi-server" or "octave
>--mpi-client".  Then we call MPI_Init() (and later MPI_Finalize()) as
>appropriate.  That is just about all that is required from the main
>code; the rest could naturally be moved to .oct.
>
>        Regards,
>
>               Andy
>
>  
>
I just created mpi_init.oct and mpi_finalize.oct, under LAM, mpi_init 
seems to initialize fine, however when I call the second function, 
mpi_finalize, I get a failure message telling me that a function has 
been called without a call to MPI_Init. This result is consistent with 
what Andy described above, however, in the LAM man page for MPI_Init it 
reads:

MPI mandates that the same thread must call MPI_Init or MPI_Init_thread 
and MPI_Finalize

This leads me to the question: Do all octave DLD functions execute in 
the same thread?

JD