Broadcast Time Warp

In many distributed computations it is necessary to ensure that the causal order in which events occur (a partial order) conforms to a total order that is derived from a correctness constraint on the computation. For example, the events of a distributed simulation must appear to be processed in simulation-time order. The Time Warp mechanism [Jeflerson 841 uses the notion of global virtual time to schedule the events of a computation to be executed in an appropriate partial order. Under Time Warp, ezecutions are subject to two sources of ineficiency, which we call transitivity delay and incremental rollback. We describe a new virtualtime synchronization protocol called Broadcast Time Warp which eliminates both of these undesirable phenomena, while retaining the synchronization seman-