Kaffemik: a distributed JVM on a single address space

Abstract

Java is increasingly used to develop large server applications. In order to provide powerful platforms for such applications a number of projects have proposed Java Virtual Machines (JVMs) that are based on network of workstations. These JVMs employ the message-passing paradigm, i.e. all communication between the distributed instances of the virtual machine take place using remote method invocation (RMI) or socket stream communication. The JVM of Kaffemik is based on multiple instances of a JVM that communicate using the shared memory paradigm. All objects that are created by virtual machines are held in a shared heap that is supported by an underlying shared memory system. By exploiting the single address space abstraction it is possible to avoid overheads that are inherent to message passing. This paper presents our first experiences with a preliminary implementation of Kaffemik. It gives a detailed discussion of the design and implementation decisions and shows a number of performance measurements that demonstrate the advantage of our shared-memory approach.