In discrete event simulation, very often the future event set is represented by a priority queue. The data structure used to implement the queue and the way operations are performed on it are often crucial to the execution time of a simulation. In this paper a new priority queue implementation strategy, the Lazy Queue, is presented. It is tailored to handle operations on the pending event set efficiently. The Lazy Queue is a kind of multi-list data structure that delays the sorting process until a point near the time where the elements are to be dequeued. In this way, the time needed to sort new elements in the queue is reduced. We have performed several experiments comparing queue access times with the access times of the implicit heap and the calendar queue. Our experimental results indicate that the Lazy Queue is superior to these priority queue implementations. Key words: Discrete Event Simulation, Priority Queue, Event List implementation, performance measurement. 1 Introduction...

Implementation of the pending event set (PES) is often crucial to the execution speed of a simulation. Parallel access implementation of the PES is a possible means of gaining performance improvement in discrete event simulation. In this paper a comparative study of some sequential and parallel access implementations of the PES is presented, these include linked lists, the Calendar Queue, the Lazy Queue, the Skew Heap and the implicit binary heap. All the parallel access implementations have a potential for an O(1) access time. A comparison of the performance of these implementations on a shared memory multiprocessor is presented. From these experiments some guide-lines have been compiled for choosing priority queue implementations for the PES. We also show that the parallel access implementations of the priority queues considered in this paper only offers what could be characterized as limited consitency. This fact may make these implementations less suitable for implementation of the...