An Experimental Study on Software Aging and Rejuvenation in Web Servers

Several studies have been conducted in order to understand the ´software aging´ phenomenon. This paper presents the results of an experimental research work, which evaluated the software aging effects on a Web server as well as the performance of a rejuvenation agent. Its main contribution is the identification and analytical validation of the factors that contribute for the Web server aging. We adopted the design of experiment technique (DOE) to characterize the aging phenomenon. The results showed evidence that the ´page type´ and ´page size´ factors were responsible for over 99% of memory size variation in httpd processes. A ´rejuvenation agent´ was implemented and integrated into the server environment to mitigate the aging effects. As a result, the size of the httpd processes could be kept under control and a higher availability and performance of the Web server could be provided, as compared to the scenario without rejuvenation