I would look at:
/MaxJobs/=<max jobs>
Maximum number of jobs each user is allowed to run at one time in
this association. This is overridden if set directly on a user.
Default is the cluster's limit. To clear a previously set value use
the modify command with a new value of -1.
Which is Association based. So you could just modify their account
directly and set it to something low.
You can also simply put their pending jobs in hold state. That way they
won't be considered for scheduling but won't be outright removed.
Setting fairshare to 0 has the same effect.
-Paul Edmon-
On 9/22/2020 7:58 PM, Brian Andrus wrote:
Well, I know of no way to 'throttle' running jobs. Once they are out
the gate, you can't stop them from leaving..
That said, your approach of setting arraytaskthrottle is just what you
want for any pending jobs.
As a preventative measure, I imagine you could set the default to 1
and then change it with a job_submit script.
As far as currently running tasks, well, you have to figure that. You
could kill/requeue them, but that can break things for the user. If
their code supports it, they could checkpoint/restart as part of the
process.
You can suspend them, but they still sit on the node waiting to be
resumed, but the node resources may get assigned to other jobs while
they wait to resume.
Brian Andrus
On 9/22/2020 2:33 PM, Ransom, Geoffrey M. wrote:
Hello
We had a user post a large number of array jobs with a short
actual run time (20-80 seconds, but mostly to the low end) and
slurmctld was falling behind on RPC calls trying to handle the jobs.
It was a bit awkward trying to slap arraytaskthrottle=5 on each of
the queued array jobs while slurmctld was having issues handling the
RPC load.
I’m looking to make a QOS with MaxJobsPerUser=50 set that I can
quickly add to a user to throttle their jobs but..
1)Adding a QOS to the user does not affect queued jobs so I still
have to get all of the users jobids and modify each on directly.
2)I queued up a test job with the QOS set and it is still running 100
jobs at a time (what I set arraytaskthrottle to in the job) and not
limiting the “user” to 50 jobs.
3)I tried adding the FLAG OverPartQOS to see if that changed the
behavior, but it did not seem to do anything. My test cluster I ran
this on doesn’t have any other QOSes defined but our production
cluster does have a partition QOS in place limiting single users to
about 80% of the CPUs with MaxTRESPerUser.
Is there a quick way to limit how many jobs a specific user can run
at one time on the cluster or in a partition if we need to throttle
them back in an emergency but we don’t want to flat out kill their jobs?
Thanks.
