Exploring Server-Centric Scalability for Social VR

Social Virtual Reality (SVR) systems are growing in both popularity and breadth. New systems are attempting to support a wider range of increasingly large social situations. A key characteristic of SVR systems is user capacity. Many systems are designed for small group discussion or team games, and support up to 20-30 users. Some support larger counts, but via special features coupled to a specific social situation. As SVR broaches medium to large gatherings (10s-1000s of people), capacity becomes a major challenge. Naïve implementations where each user communicates directly with every other will quickly overwhelm the resources of the system. The constraints on scalability have been known since the first SVR systems were created. However, while there are many systems out there, their scalability mechanisms are often application specific, and rarely openly discussed. In this paper we explore scalability in the open-source SVR Ubiq. We consider two partitioning schemes to increase relay-server capacity. We examine the current failure modes of the relay-server system, and demonstrate how these schemes improve capacity by a factor of 2-3x. We look at the interactions between the schemes and simulated user behaviour, to see what lessons can be gleaned for research into scalability for SVR.