Re: [HTCondor-users] Best strategy for matchmaking based on schedd hostname

[Todd Tannenbaum <tannenba@xxxxxxxxxxx>]

On 4/8/2020 11:33 AM, jcaballero.hep@xxxxxxxxx wrote:
> Hello,
>
>
> I need to add a constraint in my startd configuration to accept jobs
> only from one of the several schedd's serving the pool.
> IIRC, the schedd name is embedded in the GlobalJobId, right?
> What would be the recommended strategy to extract the schedd name from
> it and add it to the expression? Something like this?
>
>        split( GlobalJobId , "#" )[0] =?= my_schedd_hostname
>
>
> Any suggestion is more than welcome.
> Thanks a lot in advance.
> Cheers,
> Jose

Hi Jose,

I strongly advise that you do not reference GlobalJobId in your startd's START expression.  While it would work, it will 
result in the central manager doing a lot of extra work resulting in slower matchmaking when many jobs are queued.  The 
reason is because GlobalJobId has a unique value for every single job, and referencing a unique value in the START 
expression means that HTCondor can no longer automatically group jobs together when doing matchmaking... it will need to 
consider every single job individually.

Instead, I recommend perhaps looking at the job's "User" attribute which is owner@xxxxxxxxxxxxx maybe this works for 
you?  Then you could have in the config on your execute machine something like:
   START = splitUserName(User)[1] == "whatever"

Another idea is to simply make a custom attribute in all the jobs coming from the schedd's you care about.  On your 
submit machine(s) you could put in condor_config something like the following to create a custom attribute ScheddHostName:

  ScheddHostName = "$(FULL_HOSTNAME)"
  SUBMIT_ATTRS = $(SUBMIT_ATTRS) ScheddHostName

and then reference this custom attribute in your START expression on your execute nodes like so:

  START = ScheddHostName == "whatever.gov"

Hope the above helps,
Todd