Locally optimistic methods of concurrent simulation

A new model is presented for the simulation of large and complex systems by exploiting concurrency. Composite ELSA is a distributed asynchronous event-driven simulation model which combines the conservative and optimistic synchronization protocols, while preserving their respective advantages. This model assigns synchronization classes to processes or a hierarchy of processes, which are based on attributes of conservatism or degree of optimism. These attributes can be dynamically updated during the course of simulation, enabling processes to switch smoothly between synchronization classes. A locally optimistic synchronization protocol is introduced, and comparisons are made with two traditional protocols for parallel logic simulation on distributed memory MIMD machines