Sun recently released update 14 of the Java 6 JDK and JRE. As well as the usual collection of bug fixes, this release includes some experimental new features designed to improve the performance of the JVM (see the release notes). One of these is Escape Analysis.
To see what kind of impact escape analysis might have on my applications, I decided to try it on a couple of my more CPU-intensive Java programs. Escape analysis is turned off by default since it is still experimental. It is enabled using the following command-line option:
-XX:+DoEscapeAnalysis
Benchmark 1
The first program I tested is a statistical simulation. Basically it generates millions of random numbers (using Uncommons Maths naturally) and does a few calculations.
VM Switches: -server
95 seconds
VM Switches: -server -XX:+DoEscapeAnalysis
73 seconds
Performance improvement using Escape Analysis: 23%
Benchmark 2
The second program I tested is an implementation of non-negative matrix factorisation.
VM Switches: -server
22.6 seconds
VM Switches: -server -XX:+DoEscapeAnalysis
20.8 seconds
Performance improvement using Escape Analysis: 8%
Conclusions
These benchmarks are neither representative nor comprehensive. Nevertheless, for certain types of program the addition of escape analysis appears to be another signficant step forward in JVM performance.