Based On The Multi-stage Public I / O Services

With the explosive growth of the Internet in the last few years, Internet services have become a vital resource for many people. More and more individuals, enterprises and organizations search knowledges, informations and carry out transactions on the Internet. The concurrency demands, dynamics, and extremely robustness in Internet Services make a big challenge to the servers. Researchers and technicians take a lot of effort to the concurrency programming models and I/O processing in order to build high performance servers for Internet Services.Matthew D. Welsh proposed a new software framework called SEDA, Staged Event-Driven Architecture, in 2002. Applications are constructed as a network of event-driven stages connected with explicit queues in this model, and each stage embodies a robust, reuseable software component that performs a subset of request processing. By performing admission control on each event queue, the service can be well-conditioned to adaptive load. SEDA has taken advantages of thread-based concurrency model and event-driven concurrency model to meet the massive concurrency demand and promote the robustness of servers to adaptive load. By studying staged event-driven architecture and current I/O models, the design and implementation of common I/O service for the servers based on SEDA are described in the dissertation. The experimental results show that the OptiServer we developed has better performance on I/O operation than the well-kown Haboo Web Server does. Indeed, the followings have been done in this dissertation:(1) Study on current concurrency programming models and their impacts on I/O operation.(2) Make deep research on I/O models and I/O programming interfaces provided by operating systems.(3) The operation of network I/O and file I/O has been designed and implemented as event handlers in accordance with SEDA. Moreover, the event handlers have been wrapped into stages to provide asynchronous I/O operation for applications.(4) By performing admission control, batching control and feedback control on the stages of common I/O service, the performance of I/O operation has been improved. In coorperation with global thread resource control and allocation mechanism, the common I/O service for servers provides higher performance than current I/O operating stages on I/O operating.(5) The comparison tests of the servers based on different I/O operation have been done. The experimental results in the same test conditions show that the common I/O service can improve the performance of the servers on I/O operation.