LP A LP B LP C LP D Logical Time problem: limited concurrency each LP must process events in time stamp order LT A possible message OK to process event not OK to process yet without lookahead Each LP A using logical time declares a lookahead value L A ; the time stamp of any event generated by the LP must be ≥ LT A + L A Lookahead is necessary to allow concurrent processing of events with different time stamps (unless optimistic event processing is used) Why Lookahead is Important possible message OK to process with lookahead LT A +L A Lookahead is used in virtually all conservative synchronization protocols Essential to allow concurrent processing of events
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