[mpich-discuss] Singleton init configuration for MPICH

[Jeff Hammond]

On Tue, Aug 2, 2016 at 7:56 AM, Edric Ellis <Edric.Ellis at mathworks.co.uk>
wrote:

> Thanks for that Jeff. Are you referring to this discussion?
> http://lists.mpich.org/pipermail/devel/2016-July/000717.html
>

Yes


> If so, that shares some similarity with what I’m trying to recreate in
> MPICH. However, our code using MPICH2 makes no use whatsoever of mpiexec
> when in “connect/accept” mode, and I changing this would be rather
> invasive.
>
>
>

I agree that this should work, but as the ticket I shared indicates, it is
not implemented right now.


> It seems as though that open issue has been open for quite a while now,
> with no scheduled release for when it might be addressed – so am I correct
> in understanding that there are no known workarounds, and that essentially
> my only option for now is to stick with MPICH2?
>
>
>

You could also try Open-MPI 2.0 (
https://www.open-mpi.org/community/lists/announce/2016/07/0085.php).  They
fixed a bug related to this reported by the same person who reported the
MPICH bug, so perhaps it works for your usage.

Normally, I do not recommend Open-MPI, because it has been full of bugs
related to everything I care about for many years, but at least in this one
specific case, it is possible they have the upper hand.

Jeff


> Cheers,
>
> Edric.
>
>
>
> *From:* Jeff Hammond [mailto:jeff.science at gmail.com]
> *Sent:* Monday, August 01, 2016 6:43 PM
> *To:* MPICH <discuss at mpich.org>
> *Subject:* Re: [mpich-discuss] Singleton init configuration for MPICH
>
>
>
> It's an open issue: https://trac.mpich.org/projects/mpich/ticket/1074.
>
>
>
> There was some discussion on the devel list as of last week that might be
> of interest to you.
>
>
>
> Jeff
>
>
>
> On Mon, Aug 1, 2016 at 8:47 AM, Edric Ellis <Edric.Ellis at mathworks.co.uk>
> wrote:
>
> Hi,
>
>
>
> I need to come up with an MPICH build that allows singleton-init processes
> to use MPI_Comm_connect/accept to get connected. Our MPICH2 build uses the
> “smpd” process manager to achieve this. However, now that we’re upgrading
> to MPICH (3.1.4), I notice that the “smpd” process manager no longer
> exists. Is there a combination of process manager and PMI that allows
> connect/accept for singleton-init processes? I’ve tried a few things and
> cannot seem to find a combination that works. Here are the things I’ve
> tried:
>
>
>
> 1.       Hydra with pmi=simple – fails when attempting to launch hydra’s
> mpiexec (I don’t have the message to hand, but my recollection is that
> hydra’s mpiexec didn’t accept “-pmi_args”)
>
> 2.       Hydra with pmi=pmi2/simple – cannot be built
>
> 3.       Gforker with pmi=pmi2/simple – required a couple of tweaks
> before it could be built, and then fails in PMPI_Init_thread complaining
> “Message truncated”
>
>
>
> Is there some other combination that might work? Ideally, the
> singleton-init processes wouldn’t need to use mpiexec at all (as was the
> case with our MPICH2 build using smpd).
>
>
>
> Cheers,
>
> Edric.
>
>
>
>
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>
> --
>
> Jeff Hammond
> jeff.science at gmail.com
> http://jeffhammond.github.io/
>
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-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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