Priority Queues

Abstract

This chapter will use the queuing system in Chaps. 5 and 9, but with priority orders. The system is shown in Fig. 19.1. Everything is the same as in Fig. 5.1 (9.1) except for the arrivals. Now we have three types of arrivals: (1)lowest level is called Priority ≠1; (2) the next lowest level is Priority ≠2; and (3) the highest level is labelled Priority ≠3. Priority determines how an item is handled in a queue. In any queue all items with priority ≠3 go to the front of the queue and are serviced on a first come, first served, basis. If there are no Priority ≠3 items in the queue, then all those with Priority ≠2 go to the front of the queue and are serviced in a first come, first served, manner. All items of Priority ≠1 are serviced in the first come, first served, mode if there are no Priority ≠2 or ≠3 items in the queue. There are different priority levels because we have different types of customers. The highest priority is given to those customers who pay in cash, so there are no billing expenses, and they place many orders. Similarly, we determine the other priority levels.