[gpaw-users] MPI support without gpaw-python

[Gaël Donval]

On Tue, 2018-08-07 at 15:01 +0000, Gaël Donval via gpaw-users wrote:
> On Tue, 2018-08-07 at 16:55 +0200, Jens Jørgen Mortensen wrote:
> > On 08/07/2018 04:45 PM, Gaël Donval via gpaw-users wrote:
> > > Hi,
> > > 
> > > Is it still possible to get MPI support without compiling the
> > > custom
> > > interpreter?
> > 
> > I don't know if it still works.  Try to turn on this section:
> > 
> >      https://gitlab.com/gpaw/gpaw/blob/master/customize.py#L80
> > 
> > compile and then set the environment variable $GPAW_MPI to point to
> > your 
> > dynamic MPI library.
> 
> Hi Jens Jørgen,
> 
> That's what I did (on a standard ArchLinux distribution, nothing
> fancy,
> really). I get this:
> 
>    ----------------------------------------------------------------
> ----------
>    Open MPI has detected that this process has attempted to
> initialize
>    MPI (via MPI_INIT or MPI_INIT_THREAD) more than once.  This is
>    erroneous.
>    ----------------------------------------------------------------
> ----------
>    [hostname:25791] *** An error occurred in MPI_Init
>    [hostname:25791] *** reported by process [2821259265,0]
>    [hostname:25791] *** on a NULL communicator
>    [hostname:25791] *** Unknown error
>    [hostname:25791] *** MPI_ERRORS_ARE_FATAL (processes in this
> communicator will now abort,
>    [hostname:25791] ***    and potentially your MPI job)
> 
> Other MPI programs on that computer are working fine and a (very)
> simple mpi4py test works. For the records, the version of openmpi is
> 3.1.0.
> 
> I'll have a look at the mpi.c sources and activate whatever macro can
> help.
> 
> Gaël
> 
> > 
> > Jens Jørgen

Success (apparently) \O/

Race conditions that exist with python (multiple instances are spawned
by mpiexec) but not in gpaw-python (since it initialises MPI right
away). Once solution is to use MPI_Initialized().

I'll submit a patch tomorrow though I am not sure that this is enough.

Gaël