Distributed virtual environments (DVE), such as multi-player online games and distributed simulations may involve a massive amount of concurrent clients. Deploying distributed server architectures is currently the most prevalent way of providing such large-scale services, where typically the virtual space is divided into several distinct regions requiring each server to handle only part of the virtual world. Inequalities in client distribution may, however, cause certain servers to become overloaded, which potentially degrades the interactivity of the environment and thus renders the load balancing problem a crucial issue. Prior research has shown several approaches for avoiding uneven workload, nevertheless, addressing the problem mainly at the application layer. In this paper we focus on solving the DVE load balancing problem at the operating system level. We propose an efficient process live migration mechanism, which is optimized for processes maintaining a massive amount of network connections. Building on top of it, we have implemented a decentralized middleware that instruments process migration among the cluster nodes, attempting to equalize loads on all machines. We demonstrate the performance of the live migration mechanism on a real-world multiplayer game server and show the behavior of the load balancing engine through a realistic DVE simulation.
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