Optimism: not just for event execution any more

Optimism is a technique used by the Time Warp paradigm to make decisions about event execution under uncertainty. While the benefits of throttling the optimism of Time Warp have been studied, the benefits of extending optimism to operations besides event execution are presented. Specifically, we discuss how optimism can be mapped to fossil collection which has traditionally been assumed to be a non-recoverable operation that must be performed under global control. Optimistic Fossil Collection (OFC) is a technique for fossil collection that does not require global control. However, as states are fossil collected optimistically, a recovery mechanism is required to recover from errors. Performance results show that Time Warp using OFC can improve the performance of simulations on a network of workstations. Another benefit of OFC is that the simulation checkpoints provide for fault tolerance in more than just fossil collection.