Efficient Global Object Space Support for Distributed JVM on Cluster

We present the design of a global object space in a distributed Java Virtual Machine that supports parallel execution of a multi-threaded Java program on a cluster of computers. The global object space virtualizes a single Java object heap across machine boundaries to facilitate transparent object accesses. Based on the object connectivity information that is available at runtime, the object reachable from threads at different nodes, named as distributed-shared object, are detected. With the detection of distributed-shared objects, we can alleviate overheads in maintaining the memory consistency within the global object space. Several runtime optimization methods have been incorporated in the global object space design, including an object home migration method that reallocates the home of a distributed-shared object, synchronized method migration that allows the remote execution of a synchronized method at the home node of its synchronized object, and object pushing that uses the object connectivity information to improve access locality.