Ensuring the Performance of Apache HTTP Server Affected by Aging

Failures due to software aging are typically caused by resource exhaustion, which is often preceded by progressive software performance degradation. Response time as a customer-affecting metric can thus be used to detect the onset of software aging. In this paper, we propose the distribution-based rejuvenation algorithm (DBRA), which uses a validated M/E₂/1/K queuing model of the Apache HTTP server to decide when to trigger rejuvenation. We compare the performance of the DBRA with the one of the static rejuvenation algorithm with averaging (SRAA) presented by Avritzer et al. Simulation results show the effectiveness of the DBRA and its advantages over the SRAA in reducing the average response time. However, the DBRA generally tends to trigger rejuvenation more frequently than the SRAA, which increases the request blocking probability.