Implementing a Global Termination Condition and Collecting Output Measures in Parallel Simulation

This paper investigates how to implement arbitrary global termination conditions and collect statistics in a parallel simulation. The problem is first discussed using Chandy and Sherman's space-time framework. Then termination conditions are categorized, and termination algorithms are given for several categories. The chief problem is that if one evaluates the termination condition asynchronously with respect to the simulation, when termination is detected the simulator has already modified old attribute values needed to compute output measures. The major conclusion is that minor modification of time warp permits use any termination condition. In contrast, conservative protocols permit limitied termination conditions unless they are modified to incorporate mechanisms present in optimistic protocols.