Performance analysis of a distributed question/answering system

The problem of question/answering (Q/A) is to find answers to open-domain questions by searching a large collection of documents. Unlike Internet search engines, Q/A systems provide short, relevant answers to questions. Due to the complex natural language processing involved that is CPU intensive, and the retrieval of large number of documents that is disk intensive, the time performance of sequential Q/A systems is rather slow. This paper presents the design and performance analysis of a distributed state-of-the-art Q/A system. The design is modular and parallelism is dynamically exploited at inter and intra-question levels. Several schedule points are used to balance the load. An analytical performance model is given backed up by experimental results.