Multi-tier Priority Queues and 2-tier Ladder Queue for Managing Pending Events in Sequential and Optimistic Parallel Simulations

The choice of data structure for managing and processing pending events in timestamp priority order plays a critical role in achieving good performance of sequential and parallel Discrete Event Simulation (DES). Accordingly, we propose and evaluate the effectiveness of our novel multi-tiered (2 and 3 tier) data structures and our 2-tier Ladder Queue, for both sequential and optimistic parallel simulations, on distributed memory platforms. Our assessments use (a fine-tuned version of) the Ladder Queue, which has shown to outperform many other data structures for DES. The experimental results based on 2,500 configurations of PHOLD benchmark show that our 3-tier heap and 2-tier ladder queue outperform the Ladder Queue by 10% to 50% in simulations, particularly those with higher concurrency per Logical Process (LP), in both sequential and Time Warp synchronized parallel simulations.