Experiences in verifying parallel simulation algorithms

Abstract

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.

A formal specification and verification framework for Time Warp-based parallel simulation

“…In answering these questions, the developers considered and resolved details that previously went unnoticed. Although difficult to quantify, our experience here suggests that an easy-to-follow formal specification of the time warp protocol results in a faster, more efficient software implementation [27], [28].…”

“…However, supporting such a statement with quantitative data is difficult. This is not our first experience with developing a parallel simulator [21], [27] and, thus, our previous experience contributed substantially to the improved development time. However, this was our first attempt at building a general purpose objectoriented parallel simulation kernel, so differences in the development goals did exist.…”

Web-based network analysis and design

“…The user may specify attributes about the objects and the factory manager queries the "known" factories to locate components matching the users requirements. The query process can also be extended to perform sophisticated knowledge-based component retrievals [Penix et al 1998]. …”

“…The growth in sophistication and complexity of software systems has necessitated the use of formal mechanisms to verify and validate them [Penix et al 1998]. Automated formal methods are now employed to verify and validate designs.…”

“…Although considerable research has been carried out in the areas of composeable systems and reusable components [Penix et al 1998], the software models developed for simulation based verification and analysis are seldom reused. There are several reasons for this [Page et al 1998].…”