Socket cloning for cluster-based web servers

Abstract

Cluster-based web server is a popular solution to meet the demand of the ever-growing web traffic. However existing approaches suffer from several limitations to achieve this. Dispatcher-based systems either can achieve only coarse-grained load balancing or would introduce heavy load to the dispatcher Mechanisms like cooperative caching consume much network resources when transferring large cache objects. In this paper, we present a new network support mechanism, called Socket Cloning (SC), in which an opened socket can be migrated efficiently between cluster nodes. With SC, the processing of HTTP requests can be moved to the node that has a cached copy of the requested document, thus bypassing any object transfer between peer servers. A prototype has been implemented and tests show that SC incurs less overhead than all the mentioned approaches. In trace-driven benchmark tests, our system outperforms these approaches by more than 30% with a cluster of twelve web server nodes.