[OOD-users] Launching apps outside job system

[Dan Dietz]

Eric,

Thanks for the reply. My aim would be to get them launched one of the login
nodes. A "ssh clustername" would get you a round-robin to one of them to
balance things. FWIW, we use systemd and cgroups to throttle people and
make sure everyone gets an even slice of the login node (and knock off
anyone using more than some % of memory), so I think that would handle
those concerns for us.

As for the quick implementation, yes, actually one suggestion I got here
was to turn the front-ends into nodes in torque, and have a queue only OOD
can access which I think is similar to the proposal there. Maybe we could
dedicate a few compute node similarly and allow heavier use, but that'll
take some convincing up the chain.

I think this gives me enough information for the time being - I've got an
internal demo planned for later next month where I hope to make some
decisions on whether this is functionality we want to offer. Right now
users can use Thinlinc remote desktops to quick launch things on a login
node (there's a set of 'start' menu items) so I don't necessarily want to
provide duplicate functionality to do the same thing.

Thanks!

Dan

On Tue, Nov 20, 2018 at 3:51 PM Franz, Eric <efranz at osc.edu> wrote:

> Dan,
>
>
>
> Were you thinking of starting these on the web node, login node, or just
> any dedicated node to run these processes on demand, without the wait
> imposed by the queue?
>
>
>
> We proposed to tackle this problem in the CSSI proposal that was recently
> awarded so this is on the roadmap for next year. We discussed possibly
> building a “fork” adapter that would implement the same interface as the
> job adapters, but instead just fork + exec (or in your case, ssh + fork).
> The replacement for qstat would be a mixture of ps and inspecting
> /proc/<pid>; the “job id” would be the process id. qdel would just be kill.
> There would be problems introduced for process cleanup. Some type of
> containerization would be helpful but then that would require escalated
> privileges, complicating the implementation. Or we might investigate using
> systemd for supporting the process management.
>
>
>
> At OSC we support such lightweight processing through a “quick cluster” to
> support “VDI” apps where jobs only get 1 core and we oversubscribe jobs on
> the nodes. That is explained in the relevant portions in this thread:
> https://listsprd.osu.edu/pipermail/ood-users/2018-March/000122.html.
> While they use the same batch submission (the torque adapter, in OSC’s
> case), jobs typically take 10-30 seconds to start instead of minutes. Would
> this approach work for you in the interim? Otherwise perhaps we could
> explore another option till a more robust “fork” adapter is available.
>
>
>
> Thanks,
>
> Eric
>
>
>
> ---
>
> Eric Franz, Senior Web & Interface App Engineer
>
> Ohio Supercomputer Center
>
> An Ohio Technology Consortium (OH-TECH) Member
>
> 1224 Kinnear Road
>
> Columbus, OH 43212
>
> email: efranz at osc.edu
>
>
>
> *From: *OOD-users <ood-users-bounces+efranz=osc.edu at lists.osc.edu> on
> behalf of Dan Dietz via OOD-users <ood-users at lists.osc.edu>
> *Reply-To: *Dan Dietz <ddietz at purdue.edu>, User support mailing list for
> Open OnDemand <ood-users at lists.osc.edu>
> *Date: *Tuesday, November 20, 2018 at 8:45 AM
> *To: *"ood-users at lists.osc.edu" <ood-users at lists.osc.edu>
> *Subject: *[OOD-users] Launching apps outside job system
>
>
>
> I wonder if there is a way to launch the apps outside the job system, ie,
> directly on the cluster front-ends? We support running a few lightweight
> apps on cluster front-ends (visualizations, things like that). Is there a
> way to have it just "ssh" instead of "qsub" to start an interactive
> session?
>
>
>
> Thanks,
>
> Dan
>
>
>
> --
>
> Dan Dietz
> Senior Scientific Applications Analyst
> ITaP Research Computing, Purdue University
>


-- 
Dan Dietz
Senior Scientific Applications Analyst
ITaP Research Computing, Purdue University
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