[mpich-discuss] MPI_Comm_spawn without mpiexec

[Roland Schulz]

On Mon, Jun 18, 2012 at 10:12 AM, Pavan Balaji <balaji at mcs.anl.gov> wrote:

>
> No, Hydra doesn't support this yet.  There's a ticket for this somewhere.
>
> Can you create a wrapper script that just does "mpiexec
> ./real_application"?  That way you'll have the convenience you are
> looking for.
>

This wouldn't be very easy. I want the user to be able to execute the
binary in the regular fashion (with mpiexec) too, to give all
the flexibility. Without the wrapper this is very easy to do because I can
check whether size of comm-world is 1. So the wrapper script would need to
detect whether it is executed with mpirun/mpiexec or not. And the script
would need to work platform independent (incl Windows). Thus I would favor
a solution in C or if none exist I'll just document that MPICH requires the
app to be called with mpiexec.

Roland


>  -- Pavan
>
> On 06/18/2012 08:02 AM, Dave Goodell wrote:
> > This should generally "just work" with MPICH2 on normal workstation-type
> platforms and plain-vanilla clusters.  How are you invoking your binary
> when you "execute it directly"?
> >
> > What version of MPICH2 are you using?  What sort of platform is it on?
> >
> > -Dave
> >
> > On Jun 16, 2012, at 1:40 PM CDT, Roland Schulz wrote:
> >
> >> Hi,
> >>
> >> is it possible to create a binary which can be run directly without
> mpiexec but which can use MPI_Comm_spawn? I have a small test program which
> uses MPI_Comm_spawn and it works currently if I execute it with mpiexec.
> But if I execute it directly I get:
> >> mpiexec was unable to launch the specified application as it could not
> find an executable:
> >> Executable: -pmi_args
> >>
> >> Even if a solution would require some internal API, I would be
> interested in it. If that is not possible, what is the best way to query
> whether the application was started with or without mpiexec? Should one
> just analyze the argv before MPI_Init is called or does mpich have some API
> for that use?
> >>
> >> I would like to be able to create a binary which doesn't need to be
> executed with mpiexec to make it more user friendly so that a user which
> just wants to run on a single node can just execute the binary but the
> application uses all cores by default.
> >>
> >> Roland
> >>
> >> --
> >> ORNL/UT Center for Molecular Biophysics cmb.ornl.gov
> >> 865-241-1537, ORNL PO BOX 2008 MS6309
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> --
> Pavan Balaji
> http://www.mcs.anl.gov/~balaji
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>
>
>
>


-- 
ORNL/UT Center for Molecular Biophysics cmb.ornl.gov
865-241-1537, ORNL PO BOX 2008 MS6309
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