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Re: [HTCondor-users] 8.2.9 ALLOW_PSLOT_PREEMPTION

Hi Tom,

According to
This fix is being backported in 8.2.10.


Evan Sarmeinto
Front End Systems Software Developer
Harvard-MIT Data Center
T: 617-384-5876
E: esarmien@xxxxxxxxxxxxx
Follow us: @hmdcrce

On Wed, Aug 26, 2015 at 8:06 PM, Tom Downes <downes@xxxxxxx> wrote:


Can you define "next release"? 8.3-only or do you consider it a bug in the backported version as well?

Tom Downes
Senior Scientist and Data CenterÂManager
Center for Gravitation, Cosmology and Astrophysics
University of Wisconsin-Milwaukee

On Wed, Aug 26, 2015 at 9:43 AM, Jaime Frey <jfrey@xxxxxxxxxxx> wrote:
On Aug 25, 2015, at 1:26 PM, Jaime Frey <jfrey@xxxxxxxxxxx> wrote:

On Aug 24, 2015, at 11:49 AM, Evan Sarmiento <esarmien@xxxxxxxxxxxxx> wrote:

Hi All,

I installed HTCondor 8.2.9 and turned on ALLOW_PSLOT_PREEMPTION by setting it to True on all my startds, schedds, and the negotiator. I have two startds configured as such:

SLOT_TYPE_1 = 100%

However, when enabled, I canât get *any* pre-emption to occur. The Negotiator doesnât even attempt to pre-empt any jobs.

When I turn off ALLOW_PSLOT_PREEMPTION, I can pre-empt like jobs that use the same resources as expected.

Has anyone else run into this?

I dug into the source code a little and it appears like jobs that want pslot preemption need âWantPslotPreemptionâ in the ClassAd request, just to make sure, I made a job like this and even set nice_user so it could defenitley be pre-empted by any other job, but, no pre-emption occurs.

executable = /usr/bin/yes
universe = vanilla
output = /dev/null
error = /dev/null
log = /dev/null
nice_user = True
+WantPslotPreemption = True
queue 11

Any ideas?

First, the easy part: The WantPslotPreemption attribute is inserted by the schedd into the job ads that it sends to the negotiator to indicate that it understands a pslot preemption match, which involves claiming multiple slots on the execute machine. You shouldnât set it in your submit file.

What form of preemption are you expecting thatâs not occurring with pslot preemption enabled, user priority-based or startd rank-based? I just did a quick test with startd rank-based preemption and it worked in my test pool.

Thereâs a bug in the code that prevents pslot preemption from working for user priority-based preemption. Currently, it only works for preemption based on startd rank. Weâll fix that in the next release.

Thanks and regards,
Jaime Frey
UW-Madison HTCondor Project

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