Dynamically Compiled Artifact Sharing for Clouds

Platform as a Service (PaaS) clouds provide part of the hardware/software stack and related services to tenant applications. Increased load is handled elastically by scaling, which either modifies the number of instances an application has available on the cloud or increases their available resources. However, because all these instances run inside isolated containers, experience gained by the first instance of an application cannot be easily shared with subsequent scaled instances. This results in both increased startup time and response timeout errors for the scaled instances as well as increased performance interference for any co-located applications; reacquiring this experience is a time-consuming and resource-intensive process. We propose a scalable and secure technique to share dynamically compiled artifacts produced by the first execution instance of an application and otherwise created for intra-OS sharing only with subsequent scaled or restarted instances as a solution to these problems. Our solution abides by the usual PaaS limitations and uses a distributed and containerized cloud service, which we experimentally show to be scalable on a Docker Swarm running on top of a 6-VM cluster; also, we discuss the results of a usability survey for the service's GUI conducted with expert subjects. The effectiveness of the DCAS technique was experimentally tested on an isolated installation of the PaaS software Cloudy Foundry; we measured significant reductions in both the startup time and response errors of scaled out instances as well as performance interference to co-located tenants during scaling.