Causality information and proactive cancellation mechanisms

• Published in: Concurrency and computation Vol. 21; no. 11; pp. 1483 - 1503
• Main Authors: Chetlur, Malolan, Wilsey, Philip A.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 10-08-2009
• Subjects: cancellation; logical time; time warp; vector clocks; virtual time
• ISSN: 1532-0626; 1532-0634
• DOI: 10.1002/cpe.1399

Time Warp distributed simulations can enter a catastrophic state of cascading rollbacks where out of order (premature) event executions propagate faster than the corrective measures (anti‐messages) designed to terminate them. In this paper, a distributed, proactive cancellation mechanism designed to avoid this situation is presented. We also present a version of total clocks called Plausible Total Clocks (PTC). PTC employs a compact time vector of event counter range to address the scalability issues typically suffered by total clock solutions. That is, PTC consists of constant size vectors and are independent of the number of simulation objects in the simulation. The events generated due to an out of order execution are proactively cancelled by determining its causality relation with the already annihilated events. We present a proof of correctness of the distributed cancellation mechanism using PTC and also show that the catastrophic states are avoided with this proactive cancellation mechanism. This cancellation mechanism assumes first‐input–first‐output communication layer, static inter‐connection topology, and logical processes consisting of multiple simulation objects. Copyright © 2009 John Wiley & Sons, Ltd.