Some more in detail information on Condor's inner workings (which are not vital but might be interesting for the power user)
Matchmaking/No Queues
HTCondor does not has a concept of queues as other batch systems but uses a match making mechanism. The basic idea is, that each user and each batch node meet at a common negotiator asking and offering resources.
For example, a user submit a job to the negotiator, where the job asks for some resources as a certain amount of memory, CPU slots and so on. From the other side, a batch node will contact the negotiator offering the resources it has currently free. The negotiator will then attempt to match all requests by waiting jobs and offers by nodes while also taking the ranking of waiting jobs into account.
Thumbsketch of Condor's match making (bad luck for the [8 CPU, 12GB Mem]-jobs)
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Attachments:
Condor Matchmaking (application/gliffy+json)
Condor Matchmaking.png (image/png)
Condor Matchmaking (application/gliffy+json)
Condor Matchmaking.png (image/png)
Condor Matchmaking (application/gliffy+json)
Condor Matchmaking.png (image/png)