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From: Adam C Powell IV (hazelsct_at_[hidden])
Date: 2007-07-18 14:27:19


On Wed, 2007-07-18 at 13:44 -0400, Tim Prins wrote:
> Adam C Powell IV wrote:
> > As mentioned, I'm running in a chroot environment, so rsh and ssh won't
> > work: "rsh localhost" will rsh into the primary local host environment,
> > not the chroot, which will fail.
> >
> > [The purpose is to be able to build and test MPI programs in the Debian
> > unstable distribution, without upgrading the whole machine to unstable.
> > Though most machines I use for this purpose run Debian stable or
> > testing, the machine I'm currently using runs a very old Fedora, for
> > which I don't think OpenMPI is available.]
>
> Allright, I understand what you are trying to do now. To be honest, I
> don't think we have ever really thought about this use case. We always
> figured that to test Open MPI people would simply install it in a
> different directory and use it from there.
>
> > With MPICH, mpirun -np 1 just runs the new process in the current
> > context, without rsh/ssh, so it works in a chroot. Does OpenMPI not
> > support this functionality?
>
> Open MPI does support this functionality. First, a bit of explanation:
>
> We use 'pls' (process launching system) components to handling the
> launching of processes. There are components for slurm, gridengine, rsh,
> and others. At runtime we open each of these components and query them
> as to whether they can be used. The original error you posted says that
> none of the 'pls' components can be used because all of they detected
> they could not run in your setup. The slurm one excluded itself because
> there were no environment variables set indicating it is running under
> SLURM. Similarly, the gridengine pls said it cannot run as well. The
> 'rsh' pls said it cannot run because neither 'ssh' nor 'rsh' are
> available (I assume this is the case, though you did not explicitly say
> they were not available).
>
> But in this case, you do want the 'rsh' pls to be used. It will
> automatically fork any local processes, and will user rsh/ssh to launch
> any remote processes. Again, I don't think we ever imagined the use case
> on a UNIX-like system where there are no launchers like SLURM
> available, and rsh/ssh also wasn't available (Open MPI is, after all,
> primarily concerned with multi-node operation).
>
> So, there are several ways around this:
>
> 1. Make rsh or ssh available, even though they will not be used.
>
> 2. Tell the 'rsh' pls component to use a dummy program such as
> /bin/false by adding the following to the command line:
> -mca pls_rsh_agent /bin/false
>
> 3. Create a dummy 'rsh' executable that is available in your path.
>
> For instance:
>
> [tprins_at_odin ~]$ which ssh
> /usr/bin/which: no ssh in
> (/u/tprins/usr/ompia/bin:/u/tprins/usr/bin:/usr/local/bin:/bin:/usr/X11R6/bin)
> [tprins_at_odin ~]$ which rsh
> /usr/bin/which: no rsh in
> (/u/tprins/usr/ompia/bin:/u/tprins/usr/bin:/usr/local/bin:/bin:/usr/X11R6/bin)
> [tprins_at_odin ~]$ mpirun -np 1 hostname
> [odin.cs.indiana.edu:18913] [0,0,0] ORTE_ERROR_LOG: Error in file
> runtime/orte_init_stage1.c at line 317
> --------------------------------------------------------------------------
> It looks like orte_init failed for some reason; your parallel process is
> likely to abort. There are many reasons that a parallel process can
> fail during orte_init; some of which are due to configuration or
> environment problems. This failure appears to be an internal failure;
> here's some additional information (which may only be relevant to an
> Open MPI developer):
>
> orte_pls_base_select failed
> --> Returned value Error (-1) instead of ORTE_SUCCESS
>
> --------------------------------------------------------------------------
> [odin.cs.indiana.edu:18913] [0,0,0] ORTE_ERROR_LOG: Error in file
> runtime/orte_system_init.c at line 46
> [odin.cs.indiana.edu:18913] [0,0,0] ORTE_ERROR_LOG: Error in file
> runtime/orte_init.c at line 52
> [odin.cs.indiana.edu:18913] [0,0,0] ORTE_ERROR_LOG: Error in file
> orterun.c at line 399
>
> [tprins_at_odin ~]$ mpirun -np 1 -mca pls_rsh_agent /bin/false hostname
> odin.cs.indiana.edu
>
> [tprins_at_odin ~]$ touch usr/bin/rsh
> [tprins_at_odin ~]$ chmod +x usr/bin/rsh
> [tprins_at_odin ~]$ mpirun -np 1 hostname
> odin.cs.indiana.edu
> [tprins_at_odin ~]$
>
>
> I hope this helps,
>
> Tim

Yes, this helps tremendously. I installed rsh, and now it pretty much
works.

The one missing detail is that I can't seem to get the stdout/stderr
output. For example:

$ orterun -np 1 uptime
$ uptime
18:24:27 up 13 days, 3:03, 0 users, load average: 0.00, 0.03, 0.00

The man page indicates that stdout/stderr is supposed to come back to
the stdout/stderr of the orterun process. Any ideas on why this isn't
working?

Thank you again!

-Adam

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