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Deterministic replay systems record and reproduce the execution of a hardware or software system. While it is well known how to replay uniprocessor systems, replaying shared memory multiprocessor systems at low overhead on commodity hardware is still an open problem. This paper presents Respec, a new way to support deterministic replay of shared memory multithreaded programs on commodity multiprocessor hardware. Respec targets online replay in which the recorded and replayed processes execute concurrently.

Respec uses two strategies to reduce overhead while still ensuring correctness: speculative logging and externally deterministic replay. Speculative logging optimistically logs less information about shared memory dependencies than is needed to guarantee deterministic replay, then recovers and retries if the replayed process diverges from the recorded process. Externally deterministic …