COMPARISON OF STABILITY AND QUEUING TIMES FOR READER-WRITER QUEUES

A reader-writer queue manages two classes of customers: readers and wr iters. An unlimited number of readers can be processed in parallel; wr iters are processed serially. Both classes arrive according to a Poiss on process. Reader and writer service times are general lid random var iables. There is infinite room in the queue for waiting customers. In this paper, a reader-writer queue is considered under the following pr iority disciplines: strong reader preference (SRP), reader preference (RP), alternating exhaustive priority (AEP), writer preference (WP), a nd strong writer preference (SWP). Preemptive priority is given to rea ders under the SRP discipline, or to writers under the SWP discipline. Non-preemptive priority is accorded to readers with the RP discipline , or to writers with the WP discipline. For the AEP discipline, custom ers of a given class are served exhaustively in an alternating fashion . For the five priority disciplines, a stability condition and first m oments for the steady-state reader and writer queueing times are given . Using these analytical results, each of the five priority discipline s is seen to be optimal (among the five) in some region of the paramet er space. Simulation results are also presented. (C) 1997 Elsevier Sci ence B.V.