Towards Efficient Support for Parallel I/O in Java HPC

Modern HPC applications put forward significant I/O requirements. To deal with them, MPI provides the MPI-IO API for parallel file access. ROMIO library implements MPI-IO and provides efficient support for parallel I/O in C and Fortran based applications. On the other hand, Java based MPI-like libraries such as MPJ Express and F-MPJ have emerged but they lack parallel I/O support. Little research has been done to provide Java based ROMIO-like libraries due to the non-availability of MPI-IO-like API for the Java language. In this paper, we take the first step towards the development of parallel I/O API in Java by evaluating the newly introduced Java NIO API versus the legacy Java I/O API. We propose two simple approaches for performing parallel file I/O using NIO and evaluate them on two different computational platforms. The implementation of proposed approaches exploits the view buffers concept of NIO API to perform efficient array based file I/O operations from multiple processes. We report encouraging speedups and suggest that design of a parallel I/O API in Java should be based on the NIO API.