[J3] Question about coarray implementations

[Damian Rouson]

A student has also worked on a threads-based parallel runtime for gfortran
that was nearly complete a couple of years ago but never quite made it into
a release.  There has been some renewed interest in finishing it recently
so possibly it will appear in gfortran 14 next year.


D

On Fri, May 19, 2023 at 07:34 Jeff Hammond via J3 <j3 at mailman.j3-fortran.org>
wrote:

> It is good to know that there is a real implementation where images are
> threads.  Even process-based implementations with fork() or clone() are
> problematic, depending on the details.  Open MPI warns on fork() usage for
> a reason.
>
> I don’t expect problems with GASNet(Ex) or OpenSHMEM based
> implementations, and I think it is great to have implementations of
> coarrays based on both.
>
> Jeff
>
>
> > On 19. May 2023, at 16.41, Brad Richardson <
> everythingfunctional at protonmail.com> wrote:
> >
> > External email: Use caution opening links or attachments
> >
> >
> > Hi Jeff,
> >
> > OpenCoarrays has an openshmem backend available as well. I don't think
> > it's used very frequently, but it's seen use in the past.
> >
> > NAG's implementation is shared memory only, so I'm pretty sure it's not
> > using MPI either. I thought I heard a rumor it used openmp/threads.
> >
> > Finally, and it's of course not done yet, I'm working with the group
> > developing Caffeine, which is based on Gasnet-Ex. There's also been
> > interest in the past of developing a Gasnet backend to OpenCoarrays.
> >
> > All of that doesn't directly answer your question, but hopefully gives
> > a fuller picture of the possible implementations for coarrays.
> >
> > Regards,
> > Brad
> >
> > On Fri, 2023-05-19 at 11:46 +0000, Jeff Hammond via J3 wrote:
> >> Is anyone aware of a Fortran implementation of the coarray model
> >> where images are not OS processes?
> >>
> >> Furthermore, are there any implementations that create images at some
> >> point after entry into the main program, such as the first time a
> >> coarray is allocated, or an image query function is called?
> >>
> >> I am familiar with OpenCoarrays and Intel Fortran, both of which use
> >> MPI, and Cray Fortran, which uses a PGAS runtime that is
> >> interoperable with MPI, but no other implementations.
> >>
> >> Thanks,
> >>
> >> Jeff
> >
> >
>
>
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