Dynamic control of the join-queue lengths in saturated fork-join queues.

摘要

The analysis of fork-join queueing systems has played anudimportant role for the performance evaluation of distributed systemsudwhere parallel computations associated with the same job are carried outudand the job is considered served only when all the parallel tasks it consistsudof are served and then joined. The fork&join nodes that we considerudconsist of K 2 parallel servers each of which is equipped with two FCFSudqueues, namely the service-queue and the join-queue. The latter store theudserviced tasks waiting for being joined. This paper addresses the problemudthat under independent and exponentially distributed service time, theudprocess describing the join-queue lengths becomes instable under heavyudload. This is due to the variance of the service time distribution. Weudpropose a simple mechanism that avoids this problem, show that we canudanalytically study a set of relevant performance indices and study byudsimulation its robustness.