Condor and Preemptive Resume Scheduling

Condor is a batch job system that, unlike many other scheduling systems, allows users to access both dedicated computers and computers that are not always available, perhaps because they are used as desktop computers or are not under local control. This introduces a number of problems, some of which are solved by Condor’s preemptive resume scheduling, which is the focus of this paper. Preemptive resume scheduling allows jobs to be interrupted while running, and then restarted later. Condor uses preemption in several ways in order to implement the policies supplied by users, computer owners, and system administrators.