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Re: [HTCondor-users] jobs stuck; cannot get rid of them.

Hi Harry,

we never had 8.4 in use, so I cannot tell...

For us, it only happens if user manage to slow down machines so they do not respond for several minutes,
e.g. by filling up either all swap space quickly (by performing non-direct I/O with 56 fast jobs in parallel to jobs consuming most memory)
or by filling up and fragmenting all memory such that the InfiniBand drivers have issues allocating anything, which also makes the filesystem quite unhappy (clients not responding for > 5 minutes).

We are countering that by increasing the memory locked for swiotlb and reducing swappiness in all cgroups (which needs some hacks due to systemd bugs: https://github.com/systemd/systemd/issues/9276 )
for now. I guess that you should be able to reproduce by flooding a machine with constant heavy I/O to local scratch or by deadlocking the network card(s).
If you need some of our users to help triggering the issue on your cluster, let us know ;-).

Cheers and thanks,
	Oliver


Am 03.12.18 um 14:56 schrieb Harald van Pee:

Hi all,

does it happen newly with htcondor 8.6 ?
Never seen it here with htcondor 8.4 and debian 7,8 and 9.

Best
Harald


On Monday, December 3, 2018 10:14:48 AM CET Oliver Freyermuth wrote:

Hi together,

we also observe this regularly. Users complain they still are accounted
resources in condor_userprio without running jobs, then I go and check on
all nodes, and find condor_starters running without any job.

I'm currently using:

for A in <allOurComputeNodes>; do echo $A; ssh $A 'for P in $(pidof
condor_starter); do CHILD_CNT=$(ps --ppid $P --no-headers | wc -l); if [
$CHILD_CNT -eq 0 ]; then echo "HTCondor Bug"; pstree -p $P; kill $P; fi;
done'; done

to clean up those, but of course that may also catch starters which are just
in file transfer, or waiting for new jobs (CLAIM_WORKLIFE).

It seems to be triggered if the compute node is busy (swapping, hanging) for
a short while and not giving timely responses via network. A better fix
than my described hack would be greatly appreciated.

Cheers,
	Oliver

Am 29.11.18 um 21:13 schrieb Collin Mehring:

Hi Stephen,

We ran into this too. In our case the condor_starter process that was
handling each of those jobs didn't exit properly and was still running.
Connecting to the host and killing the stuck condor_starter process fixed
the issue.

Alternatively, restarting Condor on the hosts will also get rid of
anything still running and update the collector.

Hope that helps,
Collin

More Information for the curious:

Here's the end of the StarterLog for one of the affected slots:
08/28/18 18:51:52 ChildAliveMsg: failed to send DC_CHILDALIVE to parent
daemon at /<IP removed>/ (try 1 of 3): SECMAN:2003:TCP connection to
daemon at /<IP removed>/ failed. 08/28/18 18:53:34 ChildAliveMsg: giving
up because deadline expired for sending DC_CHILDALIVE to parent. 08/28/18
18:53:34 Process exited, pid=43481, status=0

The pid listed was for the job running on that slot, which successfully
exited and finished elsewhere.

We noticed this happening because it was affecting the group accounting
during negotiation. The negotiator would allocate the correct number of
slots using the number of jobs from the Schedd, but would then skip
negotiation for that group because it used the incorrect number of jobs
from the collector when determining current resource usage.

Here's an example where the submitter had only one pending 1-core job and
no running jobs, but there were two stuck slots with 32-core jobs from
that submitter: 11/26/18 12:40:59 group quotas: group= prod./<group
removed>/  quota= 511.931  requested= 1  allocated= 1  unallocated= 0
<...>
11/26/18 12:40:59 subtree_usage at prod./<group removed>/ is 64
<...>
11/26/18 12:41:01 Group prod./<group removed>/ - skipping, at or over
quota (quota=511.931) (usage=64) (allocation=1)>
On Thu, Nov 29, 2018 at 5:25 AM Stephen Jones <sjones@xxxxxxxxxxxxxxxx

<mailto:sjones@xxxxxxxxxxxxxxxx>> wrote:

     Hi all,
There is a discrepancy between what condor_q thinks is runing, and 
     what
     condor_status things is running. I run this set of commands to see the
     difference.
# condor_status -af JobId -af Cpus | grep -v undef | sort | sed -e 
     "s/\.0//"> s
     # condor_q  -af ClusterId  -af RequestCpus  -constraint
     "JobStatus=?=2"
| sort > q # diff s q 
     1,4d0
     < 1079641 8
     < 1080031 8
     < 1080045 8
     < 1080321 1
See; condor_status has 4 jobs that actually don't exist in condor_q 
     !?!
They've been there for days, since I had some Linux problems that 
     needed
     a reboot (not very related to htcondor.)
So I'm losing 25 slots, due to this. How can I purge this stale 
     information from the HTCondor system, good and proper?
Cheers, Ste _______________________________________________ 
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