[slurm-users] Over-riding array limits

~Stack~ i.am.stack at gmail.com
Fri Feb 23 22:13:04 MST 2018


I have a user that submits many many many jobs at once in an array.
Happily, he's a very nice user and doesn't often cause trouble.

The documentation for the job array
(https://slurm.schedmd.com/job_array.html) says:
"A maximum number of simultaneously running tasks from the job array may
be specified using a "%" separator. For example "--array=0-15%4" will
limit the number of simultaneously running tasks from this job array to 4."

Awesome. That's exactly what he is doing.

A big job recently just finished and I'm looking at my queue noticing
that no one bothered to load it to the brim this weekend leaving me with
several idle compute nodes. Meanwhile, this user has got quite a few
jobs still waiting to run with a "JobArrayTaskLimit". :-/

I've been poking at it for the last 20-30 minutes, but I'm not seeing
how I, with the power of root, can update his own "self imposed" array
limit. It's late, my attempts have not worked, and my google-fu isn't
returning any helpful results. I'm not really concerned by it, but I
would like to know should this happen again.

How can I increase a JobArrayTaskLimit?
So using the documentation example, how would I "scontrol update" the
array to be "--array=0-15%6" when jobs 0-3 are already running?

Or maybe just say "Grab X number of jobs and run them anyway"?
So again with the documentation example, maybe 0-3 are done, 4-7 are
running, and I just want to manually tell 8-10 to run anyway on
available resources leaving 11-15 under current constraints.

Thank you!

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