Delay-Bounded Scheduling A Canonical Characterization of Scheduler Nondeterminism

We provide a new characterization of scheduling nondeterminism by allowing deterministic schedulers to delay their next-scheduled task. By limiting the number of delays that an otherwise-deterministic scheduler is allowed, a bounded-exploration of a concurrent program can be done efficiently—by reduction to an equivalent exploration of a sequential program—and robustly—i.e., not dependent on bounds having to do with the number of threads, context switches, preemptions, or buffered events. Our characterization elegantly handles both event-driven asynchronous programs, and multithreaded programs with preemption and dynamic thread creation.