Experiences in verifying parallel simulation algorithms

Parallelization is a popular technique for improving the performance of discrete event simulation. Due to the complex, distributed nature of parallel simulation algorithms, debugging implemented systems is a daunting, if not impossible task. Developers are plagued with transient errors that prove difEcult to replicate and eliminate. Recently, researchers at The University of Cincinnati developed a parallel simulation kernel, WARPED, implementing a generic parallel discrete event simulator based on the Tie Warp optimistic synchronization algorithm. The intent was to provide a common base from which domain specific simulators can be developed. Due to the complexity of the Tie Warp algorithm and the dependence of many simulators on the simulation kernel’s correctness, a formal specification was developed and verified for critical aspects of the Tie Warp system. This paper dexribes these specifications, their verification and their interaction with the development process.