DetLock: Portable and Efficient Deterministic Execution for Shared Memory Multicore Systems

Abstract

Multicore systems are not only hard to program but also hard to test, debug and maintain. This is because the traditional way of accessing shared memory in multithreaded applications is to use lock-based synchronization, which is inherently non-deterministic and can cause a multithreaded application to have many different possible execution paths for the same input. This problem can be avoided however by forcing a multithreaded application to have the same lock acquisition order for the same input. In this paper, we present DetLock, which is able to run multithreaded programs deterministically without relying on any hardware support or kernel modification. The logical clocks used for performing deterministic execution are inserted by the compiler. For 4 cores, the average overhead of these clocks on tested benchmarks is brought down from 20% to 8% by applying several optimizations. Moreover, the overall overhead, including deterministic execution, is comparable to state of the art systems such as Kendo, even surpassing it for some applications, while providing more portability.