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myschedd

In CERN's HTCondor batch system, there are multiple schedds, but users are assigned to a particular schedd. This is to make things simple, so that logging into, for instance, any LXPLUS machine, HTCondor commands can be run and your jobs can be queried without any knowledge of how the infrastructure is organized.

However, there are occasionally problems with schedds. For instance schedds can get busy! Since the usage is as hard to predict as the users that use them, how busy schedds can get is uneven. Therefore it might be useful to occasionally change schedd. Previously this required setting arcane environment variables. Now the tool myschedd allows this.

Showing the current configuration

$ myschedd show
User 'bejones' in pool 'share'
Current schedd: bigbird18.cern.ch
Other schedds used recently: bigbird08.cern.ch

Note the output shows not only the schedd you are currently assigned to, but also ones you've used previously. If you have jobs running on those other schedds, you can query them like so:

$ condor_q -name bigbird08.cern.ch

Switching to a new schedd

$ myschedd bump
Selected best schedd 'bigbird19.cern.ch' for user 'bejones' in pool 'share'

"Bump" will choose the least loaded schedd to use. We can see that our schedds list gets updated:

$ myschedd show
User 'bejones' in pool 'share'
Current schedd: bigbird19.cern.ch
Other schedds used recently: bigbird08.cern.ch, bigbird18.cern.ch

Setting a schedd explicitly

You normally won't want to do this, as the schedd is chosen specifically to be lightly used. However there may be circumstances you want to be explicit. First of all, it's worth remembering how to query the schedds that can be used:

$ condor_status -schedd
Name               Machine            RunningJobs   IdleJobs   HeldJobs

bigbird08.cern.ch  bigbird08.cern.ch         5698       5670        251
bigbird09.cern.ch  bigbird09.cern.ch         4009       1237       2803
bigbird10.cern.ch  bigbird10.cern.ch         4850         50          5
bigbird11.cern.ch  bigbird11.cern.ch         4089        846          1
bigbird12.cern.ch  bigbird12.cern.ch         7498      22593          1
bigbird13.cern.ch  bigbird13.cern.ch         7688        643       6314
bigbird14.cern.ch  bigbird14.cern.ch         1237         23        489
bigbird15.cern.ch  bigbird15.cern.ch         5466       3517          0
bigbird16.cern.ch  bigbird16.cern.ch         7913      24603        521
bigbird17.cern.ch  bigbird17.cern.ch          808       9844          0
bigbird18.cern.ch  bigbird18.cern.ch         1200         72          0
bigbird19.cern.ch  bigbird19.cern.ch           22          1          1
bigbird98.cern.ch  bigbird98.cern.ch            0          0         65
bigbird99.cern.ch  bigbird99.cern.ch            0          0          0
ce-test.cern.ch    ce-test.cern.ch              0          0          0
ce503.cern.ch      ce503.cern.ch             4417        305          4
ce504.cern.ch      ce504.cern.ch             4875        284          1
ce505.cern.ch      ce505.cern.ch             4471        277          2
ce506.cern.ch      ce506.cern.ch             4655        159          0
ce507.cern.ch      ce507.cern.ch             4003        239          0
ce508.cern.ch      ce508.cern.ch             3726        406          1
ce509.cern.ch      ce509.cern.ch             3635        361          3
ce510.cern.ch      ce510.cern.ch             4411        334          1
ce511.cern.ch      ce511.cern.ch             4262        321          3
ce512.cern.ch      ce512.cern.ch             4126        387          2
ce513.cern.ch      ce513.cern.ch             4186        345          0
ce514.cern.ch      ce514.cern.ch             4232        187          0
ce515.cern.ch      ce515.cern.ch             3195        212          0
ce516.cern.ch      ce516.cern.ch             2959         95          0
cehpc.cern.ch      cehpc.cern.ch               36         13          0
condorce01.cern.ch condorce01.cern.ch        4028        149          1

                TotalRunningJobs      TotalIdleJobs      TotalHeldJobs


         Total            111695              73173              10469

It should be stressed that you cannot select the "CE" machines as user schedds. The tool won't allow it in any case:

$ myschedd set ce503.cern.ch
Error: HTTP code: 404: Requested schedd (ce503.cern.ch) is not known

Setting it to something sensible will work:

$ myschedd set bigbird08.cern.ch
$ myschedd show
User 'bejones' in pool 'share'
Current schedd: bigbird08.cern.ch
Other schedds used recently: bigbird18.cern.ch, bigbird19.cern.ch