A Parallel XPath Engine Based on Concurrent NFA Execution

The importance of XPath in XML filtering systems has led to a significant body of research on improving the processing performance of XPath queries. Most of the work, however, has been in the context of a single processing core. Given the prevalence of multicore processors, we believe that a parallel approach can provide significant benefits for a number of application scenarios. In this paper we thus investigate the use of multiple threads to concurrently process XPath queries on a shared incoming XML document. Using an approach that builds on YFilter, we divide the NFA into several smaller ones for concurrent processing. We implement and test two strategies for load balancing: a static approach and a dynamic approach. We test our approach on an eight-core machine, and show that it provides reasonable speedup up to eight cores.