Design of scalable Java']Java message-passing communications over InfiniBand

This paper presents ibvdev a scalable and efficient low-level Java message-passing communication device over InfiniBand. The continuous increase in the number of cores per processor underscores the need for efficient communication support for parallel solutions. Moreover, current system deployments are aggregating a significant number of cores through advanced network technologies, such as InfiniBand, increasing the complexity of communication protocols, especially when dealing with hybrid shared/distributed memory architectures such as clusters. Here, Java represents an attractive choice for the development of communication middleware for these systems, as it provides built-in networking and multithreading support. As the gap between Java and compiled languages performance has been narrowing for the last years, Java is an emerging option for High Performance Computing (HPC). The developed communication middleware ibvdev increases Java applications performance on clusters of multicore processors interconnected via InfiniBand through: (1) providing Java with direct access to InfiniBand using InfiniBand Verbs API, somewhat restricted so far to MPI libraries; (2) implementing an efficient and scalable communication protocol which obtains start-up latencies and bandwidths similar to MPI performance results; and (3) allowing its integration in any Java parallel and distributed application. In fact, it has been successfully integrated in the Java messaging library MPJ Express. The experimental evaluation of this middleware on an InfiniBand cluster of multicore processors has shown significant point-to-point performance benefits, up to 85% start-up latency reduction and twice the bandwidth compared to previous Java middleware on InfiniBand. Additionally, the impact of ibvdev on message-passing collective operations is significant, achieving up to one order of magnitude performance increases compared to previous Java solutions, especially when combined with multithreading. Finally, the efficiency of this middleware, which is even competitive with MPI in terms of performance, increments the scalability of communications intensive Java HPC applications.