Condor

Condor: Making best use of the computers in the teaching labs

Introduction

The Condor Project enables us to run batch jobs on the pool of desktop computers around the department, that would otherwise be standing idle. Condor is particularly useful for high 'throughput' computing, such as an ensemble of independent model simulations, used to evaluate explore parameter-space.

Basic commands

Our 'submission host' is condor.ggy.bris.ac.uk. If you login to that machine, you can review the status of all the machines in the 'condor pool' using the command condor_status:

Name               OpSys      Arch   State     Activity LoadAv Mem   ActvtyTime

slot1@GEOG-B224.gg WINNT51    INTEL  Owner     Idle     0.000  1661  0+01:30:04
slot2@GEOG-B224.gg WINNT51    INTEL  Owner     Idle     0.010  1661  0+01:30:05
slot1@geog-a105.gg WINNT51    INTEL  Claimed   Busy     1.130  1661  0+01:02:57
slot2@geog-a105.gg WINNT51    INTEL  Claimed   Busy     1.130  1661  0+01:02:58
slot1@geog-c200.gg WINNT51    INTEL  Unclaimed Idle     0.000  1662  0+00:00:04
slot2@geog-c200.gg WINNT51    INTEL  Unclaimed Idle     0.040  1662  0+00:00:00
...
...
                     Total Owner Claimed Unclaimed Matched Preempting Backfill

       INTEL/WINNT51   191    78     109         4       0          0        0

               Total   191    78     109         4       0          0        0

Typically you will get several screen's full of output, so I've chopped out the middle part of the listing, leaving just a few at the top and the final summary, given at the end.

From the listing, you can see that:

• The PC called GEOG-B224 has someone logged into it, indicated by the keyword Owner, but it is not working hard, as it is Idle.
• In contrast, geog-a105 is marked as Claimed, indicating that it has been grabbed by condor, and it working hard, Busy.
• The third possible state is exemplified by geog-c200, which is neither claimed nor in interactive use.

The final summary tells us that at the time of writing, the pool contains 191 PCs, 78 of which has a user logged in, 109 are claimed by condor and 4 remain unclaimed.

Another view of the state-of-play is given by condor_q:

 ID      OWNER            SUBMITTED     RUN_TIME ST PRI SIZE CMD               
 51.0   ggdagw          4/22 13:21   0+01:30:07 R  0   3.7  test.bat          
...
...
 51.15  ggdagw          4/22 13:21   0+01:33:46 I  0   3.4  test.bat   
...
...
150 jobs; 44 idle, 106 running, 0 held   

Here we see that:

• job 51.0 was submitted at 13:21 on the 22nd of April, has been running for just over an hour and a half, and that the job executable is called 'test.bat'
• We can also see that job 51.15 is idling, rather than running.
• In total 106 of the 150 jobs submitted to condor are running, and accordingly 44 are still waiting to run and so are idle.