CCJ: object-based message passing and collective communication in Java

CCJ is a communication library that adds MPI-like message passing and collective operations to Java. Rather than trying to adhere to the precise MPI syntax, CCJ aims at a clean integration of communication into Java’s object-oriented framework. For example, CCJ uses thread groups to support Java’s multithreading model and it allows any data structure (not just arrays) to be communicated. CCJ is implemented entirely in Java, on top of RMI, so it can be used with any Java virtual machine. The paper discusses three parallel Java applications that use collective communication. It compares the performance (on top of a Myrinet cluster) of CCJ, RMI and mpiJava versions of these applications, and also compares the code complexity of the CCJ and RMI versions. The results show that the CCJ versions are significantly simpler than the RMI versions and obtain a good performance. A detailed performance comparison between CCJ and mpiJava is given using the Java Grande Forum MPJ benchmark suite.