Class-Based Continuous Query Scheduling in Data Stream Management Systems

The emergence of Data Stream Management Systems (DSMS) facilitates implementing many types of monitoring applications via continuous queries (CQs). However, different monitoring applications will have different quality-of-service (QoS) requirements for detecting events. For example, the CQs for detecting anomalous events (e.g., fire, flood) have stricter response time requirements over CQs which are for logging and keeping statistical information of interesting physical phenomena. Traditional DSMSs treat all the CQs as being equally important in the system and attempt to optimize their overall performance. In particular, they employ a CQ scheduler to decide the execution order of CQs to achieve a global performance goal and as such perform badly in an environment where CQs have different importance levels. The hypothesis of this research is that there is a need for a suite of schedulers that optimizes the response time of important CQs while satisfying the requirements of the other, less important classes and taking into consideration the underlying processing environment. Toward this, we first develop the Continuous Query Class (CQC) scheduler for single-core / single-process systems which is assumed by many of the current DSMS prototypes, including our own, AQSIOS. Then, we propose the Adaptive Broadcast Disks scheduler (ABD) which is more suitable for dual-core environments. After that, we extend our work to multi-core environments to take advantage of modern machine architectures and their processing capabilities. We propose the Multi-core Broadcast Disk scheduler (MBD) which optimizes the response time of the critical CQs while maintaining acceptable performance for less-critical classes. In addition, it also utilizes the cores efficiently and provides better performance. We demonstrate the effectiveness of our schedulers through a thorough experimental evaluation using new metrics under AQSIOS, our prototype DSMS, and SimAQSIOS, a simulator that closely mimics AQSIOS