Improving the performance of JVM startup using the shared class cache

Abstract

The Java Virtual Machine (JVM) is responsible for executing all Java programs, so performance improvements in the JVM, especially pertaining to the startup of an application, have wide-ranging impact. This paper presents a solution that reduces the bottleneck by analyzing and optimizing various data structures inside the JVM before a Java application starts executing. The shared class cache, which was added to IBM's J9 VM to share classes and other immutable data across multiple runs of a JVM, is expanded to include additional data. Runtime improvements of between 15% and 20% were achieved in standard benchmark programs.