FlexRPC: A flexible Remote Procedure Call facility for modern cluster file systems

The concept of Remote Procedure Call (RPC) was proposed more than 30 years ago. Although various RPC systems have been studied and implemented, the existing RPC systems lack many crucial features and flexibility required for building modern cluster file systems .This paper presents FlexRPC, a flexible user-level RPC system that enables to develop high-performance cluster file systems easily. FlexRPC ensures client-side thread-safeness and fully supports multithreaded RPC servers. Parallel and serial multicasting mechanisms allow for implementing sophisticated replication in modern cluster file systems. The remote procedure can be invoked using both UDP and TCP transports with at-most-once semantics. The concurrent call requests are handled by a set of worker threads on the client and server side where the number of workers varies dynamically according to the request rate. In addition, the semantics and the specification of remote procedures are designed to be as close as possible to SunRPC. The experimental results show that FlexRPC improves both latency and bandwidth significantly in spite of added functionalities. We also demonstrate the performance and the flexibility provided by FlexRPC by building working prototype of cluster file system called Kadoop on top of FlexRPC.