[GE users] resource allocation and race condition

Olesen, Mark Mark.Olesen at arvinmeritor.com
Fri Oct 15 09:57:11 BST 2004

With the change to v6, I am hoping to tackle a longstanding problem.

My applications all run with floating licenses that I track via a load
sensor and the following type of consumable resource:

  #name shortcut type relop requestable consumable default urgency
  foo   foo      INT  <=    YES         YES        0       1000

Assuming that I only have a single float license 'foo', I can
'qsub -l foo=1' a job.  After a while I submit two (2) new jobs with the
same resource requirement(s). Both these jobs wait politely in the queue,
since the resource 'foo' is unavailable.  After the first job finishes, and
the load reports get correctly updated, *both* of the jobs in the queue try
to grab the 'foo' resource (almost) simultaneously.
How can I circumvent such a race condition? 

The last paragraph from
states the following:
"Grid Engine uses both information sources and does its best to derive
 from this how much of the resource is really available."

Is there a special setup required to get the '-l' resource request
registered immediately, or is this information simply misleading?

Do I need to use prolog/epilog to manipulate something?
Is there a way of (mis)using the advance reservation to solve this problem? 


Dr. Mark Olesen
Thermofluid Dynamics Analyst
ArvinMeritor Light Vehicle Systems
ArvinMeritor Emissions Technologies GmbH
Biberbachstr. 9
D-86154 Augsburg, GERMANY
tel: +49 (821) 4103 - 862
fax: +49 (821) 4103 - 7862
Mark.Olesen at ArvinMeritor.com

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