Web代理服务器缓存置换算法研究

目前Web代理服务器中的缓存机制普遍都以提高缓存命中率为目标,来设计相应的页面置换算法,一般并不考虑命中页面因过期失效而需要额外的验证及更新这一因素。为此,提出了改进的页面缓存效益模型,对包括页面验证更新在内的各种相关因素进行了综合考虑,以缓存效益系统最优为目标提出Web代理服务器中缓存置换算法——PCR;并基于合理的假设证明了该算法的最优性。最后,通过与LRU-K、Hybrid等算法的比较实验,验证了PCR算法的有效性。

Research on Web Caching Replacement Algorithm in Proxy Server

The main aim of current Web caching is to get higher hit ratio, and normally the validation and freshness of outdated pages are not considered in their replacement model. A new improved cache profit model is defined, the freshness factors of Web pages are reasonably taken into account. Based on the profit model, a new replacement al-gorithm—PCR (proxy cache replacement) is presented, and it can be proved optimal under the rational hypothesis. At last, a series of experiments indicates that PCR is efficient.