GMI: Flexible and Efficient Group Method Invocation for Parallel Programming

We present a generalization of Java’s Remote Method Invocation model (RMI) providing an efficient group communication mechanism for parallel programming. Our Group Method Invocation model (GMI) allows methods to be invoked either on a single object or on a group of objects, the latter possibly with personalized parameters. Likewise, result values and exceptions can be returned normally (as with RMI), discarded, or, when multiple results are produced, combined into a single result. The different method invocation and reply handling schemes can be combined orthogonally, allowing us to express a large spectrum of communication mechanisms of which RMI and MPI-style collective communication are special cases. With GMI, the invocation and reply schemes can be selected for each method individually at run time. GMI has been implemented in the Manta high-performance Java system. Using several micro-benchmarks and applications (partially taken from the Java Grande benchmark set), we investigate GMI’s runtime efficiency and compare to the collective communication operations from the mpiJava library. Our prototype implementation performs competitively to or even faster than mpiJava.