[torqueusers] poll_jobs server parameter setting behaviour
garrick at usc.edu
Thu May 29 11:42:19 MDT 2008
On Thu, May 29, 2008 at 03:30:17AM -0700, Virendra Pratap. Singh alleged:
> Hi All,
> I want to understand the behaviour of "poll_jobs" torque server
> parameter. The description of this from the documentation
> poll_jobs <BOOLEAN> TRUE (FALSE in TORQUE 1.2.0p5 and
> earlier) if set to TRUE, pbs_server will poll job info from mom's
> over time and will not block on handling requests which require this job
> information. If not set, no polling will occur and if job information
> is requested which is stale, pbs_server may block while it attempts to
> update this information. NOTE: For large systems, this value should be
> set to TRUE.
> So this is the situation in which I want to understand its behavior. I
> have this parameter set to TRUE. I do a "qstat" to enquire about my
> submitted job. I believe if the server has a NON stale data for this job
> with itself it will return that. Incase the job data is stale it will
> make a non blocking call to the respective processing nodes mom for the
> fresh info on this job. Since the call is non blocking, due to any
> reason the mom/server communication doesn't goes through, then WHAT will
> be the info returned by the server for this qstat request.
> Will the server return the STALE info in this case or what?
If not set, pbs_server doesn't request job info from MOMs until someone does a
qstat. Then pbs_server sends *blocking* job status requests to each MOM if the
in-memory information is not current. This is OK on smaller clusters.
If set, pbs_server regularly polls for job status info on a set time interval
When someone does a qstat, there is no need to block because the in-memory
information is always relatively current.
Garrick Staples, GNU/Linux HPCC SysAdmin
University of Southern California
Please avoid sending me Word or PowerPoint attachments.
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