DETECTING ENF EVENT PREDICATES IN DISTRIBUTED SYSTEMS

Detection of global event predicates is an important issue for distrib uted systems, particularly for debugging and monitoring of such system s, This paper defines event normal form (ENF) event predicates, and th en provides an on-line distributed algorithm to detect the first occur rence of such a predicate, We extend the algorithm to detect parameter ized predicates, and develop a multithreaded matcher that will detect multiple instances of an ENF predicate, Measurements show that the alg orithm is very fast, taking 10-20 mu s to process each event message, depending upon the predicate complexity, We believe that this combinat ion of speed and flexibility can make the algorithm very useful for on -line monitoring of distributed systems, (C) 1997 Academic Press.