An Approach to Buffer Management in Java HPC Messaging

One of the most challenging aspects to designing a Java messaging system for HPC is the intermediate buffering layer. The lower and higher levels of the messaging software use this buffering layer to write and read messages. The Java New I/O package adds the concept of direct buffers, which—coupled with a memory management algorithm—opens the possibility of efficiently implementing this buffering layer. In this paper, we present our buffering strategy, which is developed to support efficient communications and derived datatypes in MPJ Express—our implementation of the Java MPI API. We evaluate the performance of our buffering layer and demonstrate the usefulness of direct byte buffers.