Design and Implementation of Parallel Debugger and Profiler for MPJ Express

TL;DR

This paper introduces debugging and profiling tools for MPJ Express, enabling easier development of parallel Java applications on HPC systems by extending existing tools and maintaining compatibility.

Contribution

The paper presents MPJDebug and MPJProf, novel tools that integrate with Eclipse and TAU to support debugging and profiling of MPJ Express applications, filling a critical gap.

Findings

MPJDebug integrates with Eclipse for parallel Java debugging.

MPJProf leverages TAU for profiling MPJ Express applications.

Profiling overhead with MPJProf is negligible.

Abstract

MPJ Express is a messaging system that allows computational scientists to write and execute parallel Java applications on High Performance Computing (HPC) hardware. Despite its successful adoption in the Java HPC community, the MPJ Express software currently does not provide any support for debugging and profiling parallel applications and hence forces its users to rely on manual and tedious debugging/profiling methods. Support for such tools is essential to help application developers increase their overall productivity. To address this we have developed debugging and profiling tools for MPJ Express, which are the main topic of this paper. Key design goals for these tools include: 1) maintain compatibility with existing logging, debugging, and visualizing tools, 2) build these tools by extending existing debugging/profiling tools instead of reinventing the wheel. The first tool, named MPJDebug, builds on the open-source Eclipse Integrated Development Environment (IDE). It provides an Eclipse-based plugin developed using the Eclipse Plugin Development Environment (PDE). The default Eclipse debugger currently does not support debugging parallel applications running on a compute cluster. The second tool, named MPJProf, is a utility based on Tuning and Analysis Utility (TAU)-an open-source performance evaluation tool. Our goal here is to exploit TAU to profile Java applications parallelized using MPJ Express by generating profiles and traces, which can later be visualized using existing tools like paraprof and Jumpshot. Towards the end of the paper, we quantify the overhead of using MPJProf, which we found to be negligible in the profiling stage of parallel application development.