Using Micro-Reboots to Improve Software Rejuvenation in Apache Tomcat

As software complexity increases so does the difficulty in solving all software defects before the production stage, even with advanced software testing tools. Those software defects are often the cause for application crashes. To tolerate application crashes the industry has adopted several clustering techniques: server-redundancy, load-balancers and server-failover. The latest trend goes towards the development of self-healing techniques that automate the recovery procedures and prevent the occurrence of unplanned failures. In recent years a particular software problem has been studied: software aging. Software aging is described as the progressive degradation of the running software that may lead to crashes. To solve software aging a mechanism has been proposed: software rejuvenation. In essence software rejuvenation is a restart operation that causes the software to return to maximum performance thus avoiding the software crash. In this report we study an enhanced rejuvenation technique: MicroRebooting. A Micro-Reboot is a reboot done in a more fine-grained component than the whole application. Our experimental study aims to fill that void by studying the feasibility of using Micro-Reboots in Apache Tomcat. We implemented a prototype Micro-Reboot framework in that Web-Server and did an experimental study to evaluate its effectiveness. * This research work is carried out under the FP6 Network of Excellence CoreGRID funded by the European Commission (Contract IST-2002-004265).