[torqueusers] limit the number of jobs a user can submit

Martin Siegert siegert at sfu.ca
Fri Sep 30 12:43:53 MDT 2011


I know this has been discussed before, but I believe an important
aspect has been overlooked:

Moab has a limit on the number of jobs it can handle: the MAXJOB

"Specifies the maximum number of simultaneous jobs which can be evaluated
by the scheduler. If additional jobs are submitted to the resource manager,
Moab will ignore these jobs until previously submitted jobs complete."

This allows for a trivial denial-of-service attack:
Simply submit a job array with at least MAXJOB+1 elements.

After that moab will disregard all further jobs for scheduling
even if they have a much higher priority than the array job elements.

I have not yet found a way of preventing this DoS attack.
The most logical solution to me would be to expand the "max_user_queuable"
specification to allow for a server wide setting, not just a per
queue setting, i.e.,

set server max_user_queuable = 1000

Is that a feasible solution?
(and, yes, I'd like this limit to be in torque and not in moab because
the user will get an immediate response from qsub).


Martin Siegert
Simon Fraser University

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