Evaluating Degrees of Isolation between Tenants enabled by Multitenancy Patterns for Cloud-hosted Version Control Systems (VCS)

Abstract

When implementing multitenancy for cloud-hosted applications, one of the main challenges to overcome is how to enable the required degree of isolation between tenants so that the required performance, resource utilization, and access privileges of one tenant does not affect other tenants. This paper applies COMITRE (COmponent-based approach to Multitenancy Isolation Through request RE-routing) to empirically evaluate the degree of isolation between tenants enabled by multitenancy patterns for cloud-hosted Version Control System (VCS). We implemented three multitenancy patterns (i.e., shared component, tenant-isolated component, and dedicated component) by developing a multitenant component using the FileSystem SCM plugin integrated within Hudson. The study confirmed that dedicated component provides the highest degree of isolation between tenants (compared to shared component and tenant-isolated component) in terms of error% (i.e., the percentage oferrors with unacceptably slow response times) and throughput. The system load of tenants showed no variability, and hence did not influence the degree of tenant isolation for all the three multitenancy patterns. We also provide a summary of recommended multitenancy patterns for optimizing performance and utilization of resources for cloud-hosted software services, as well as recommendations to guide an architect in implementing multitenancy isolation on similar VCS tools like Subversion and CVS.