Abstract

The computational science community is reluctant to write large-scale
computationally-intensive applications in Java due to concerns over
Java's poor performance,
despite the claimed software engineering advantages of its
object-oriented features.
Naive Java implementations of numerical algorithms can
perform poorly compared to corresponding Fortran or C implementations.
To achieve high performance,
Java applications must be designed with good performance as a primary
goal.
This paper presents the object-oriented design and implementation of two
real-world applications from the field of Computational Fluid Dynamics
(CFD):
a finite-volume fluid flow solver
(LAURA, from NASA Langley Research Center),
and an unstructured mesh adaptation algorithm
(2D_TAG, from NASA Ames Research Center).
This work builds on our previous experience with the design of
high-performance numerical libraries in Java.
We examine the performance of the applications using the currently
available Java infrastructure and show that the Java version of the
flow solver LAURA performs almost within a factor of 2
of the original procedural version.
Our Java version
of the mesh adaptation algorithm
2D_TAG performs within a factor of 1.5 of its original
procedural version on certain platforms.
Our results demonstrate that object-oriented software design
principles are not necessarily inimical to high performance.