Server Transfer Delays in a Dual Resource Constrained Parallel Queueing System

Abstract

Simulation is used to evaluate a number of server assignment prodecures within a system of parallel queues. There are less servers than parallel single-channel service facilities and server transfer between facilities is allowed. Server transfer involves a deterministic time delay. Job interarrival times and service times follow the negative exponential distribution. Evaluated assignment procedures include, (1) rules incorporating parametrically weighted transfer times, and (2) rules permitting transfer only when a fixed minimum amount of time has elapsed. These rules have the effect of delaying server assignment. Three conclusions of interest to the practicing manager are the primary result of the simulation: (1) Increasing server transfer time increases mean flow time, flow time variance, and the percent of time the server spends transferring. (2) Using rules to delay server assignment reduces these criteria when compared with rules which do not delay assignment. A manager should consider delaying assignment when server transfer time becomes greater than zero. (3) Delaying server assignment appears to have a-greater affect on mean flow time than choosing a particular assignment rule.