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Subject: Re: [OMPI devel] HOSTNAME environment variable
From: Nadia Derbey (Nadia.Derbey_at_[hidden])
Date: 2010-01-22 10:36:40


On Fri, 2010-01-22 at 08:22 -0700, Ralph Castain wrote:
> A quick and easy way to answer my question of slurm vs ompi:
>
> Just do "srun script-that-echos-hostname-and-gethostname". If you get the right hostnames, then OMPI is to blame, not slurm.
>

No, I'm not...
Will check the configuration.

Thanks a lot,
Nadia

> On Jan 22, 2010, at 8:07 AM, Ralph Castain wrote:
>
> > Hi Nadia
> >
> > That sounds like a bug in your SLURM config file - SLURM certainly doesn't propagate "hostname" by default as that would definitely mess things up for more than OMPI.
> >
> > Are you sure that SLURM is propagating the environment (something I have never seen before)? Or is OMPI mistakenly picking it up and propagating it?
> >
> > On Jan 22, 2010, at 7:25 AM, Nadia Derbey wrote:
> >
> >> Hi,
> >>
> >> I'm wondering whether the HOSTNAME environment variable shouldn't be
> >> handled as a "special case" when the orted daemons launch the remote
> >> jobs. This particularly applies to batch schedulers where the caller's
> >> environment is copied to the remote job: we are inheriting a $HOSTNAME
> >> which is the name of the host mpirun was called from:
> >>
> >> I tried to run the following small test (see getenv.c in attachment - it
> >> substantially gets the hostname once through $HOSTNAME, and once through
> >> gethostname(2)):
> >>
> >> ------------
> >> [derbeyn_at_pichu0 ~]$ hostname
> >> pichu0
> >> [derbeyn_at_pichu0 ~]$ salloc -N 2 -p pichu mpirun ./getenv
> >> salloc: Granted job allocation 358789
> >> Processor 0 of 2 on $HOSTNAME pichu0: Hello World
> >> Processor 0 of 2 on host pichu93: Hello World
> >> Processor 1 of 2 on $HOSTNAME pichu0: Hello World
> >> Processor 1 of 2 on host pichu94: Hello World
> >> salloc: Relinquishing job allocation 358789
> >> ------------
> >>
> >> Shouldn't we be getting the same value when using getenv("HOSTNAME") and gethsotname()?
> >> Applying the following small patch, we actually do.
> >>
> >> Regards,
> >> Nadia
> >>
> >> --------------
> >>
> >> Do not propagate the HOSTNAME environment variable on remote hosts
> >>
> >> diff -r 4ab256be2a17 orte/orted/orted_main.c
> >> --- a/orte/orted/orted_main.c Wed Jan 20 16:45:07 2010 +0100
> >> +++ b/orte/orted/orted_main.c Fri Jan 22 14:54:02 2010 +0100
> >> @@ -299,12 +299,17 @@ int orte_daemon(int argc, char *argv[])
> >> */
> >> orte_launch_environ = opal_argv_copy(environ);
> >>
> >> + /*
> >> + * Set HOSTNAME to the actual hostname in order to avoid propagating
> >> + * the caller's HOSTNAME.
> >> + */
> >> + gethostname(hostname, 100);
> >> + opal_setenv("HOSTNAME", hostname, true, &orte_launch_environ);
> >>
> >> /* if orte_daemon_debug is set, let someone know we are alive right
> >> * away just in case we have a problem along the way
> >> */
> >> if (orted_globals.debug) {
> >> - gethostname(hostname, 100);
> >> fprintf(stderr, "Daemon was launched on %s - beginning to initialize\n", hostname);
> >> }
> >>
> >> <getenv.c>_______________________________________________
> >> devel mailing list
> >> devel_at_[hidden]
> >> http://www.open-mpi.org/mailman/listinfo.cgi/devel
> >
>
>
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>

-- 
Nadia Derbey <Nadia.Derbey_at_[hidden]>