Keeping Your Java Hot by Solving the JVM Warmup Problem

Track: Java Platform
Java bytecodes and class files deliver on the original vision of “write once, run anywhere”. Using a Just-in-Time (JIT) compiler allows JVM-based applications to compile only the code that’s being used frequently and optimise it precisely for how it is being used. Using techniques like speculative optimisation can often deliver better performance than static, Ahead-of-Time (AOT) compiled code. However, this flexibility and performance comes at a cost. Each time the JVM starts an application, it must perform the same analysis to find hot spots of code and compile them. This is referred to as the application warmup time. In this session, we’ll look at several approaches to how this problem can be alleviated or even eliminated. Specifically: • Generating a JIT compiler profile of a running, warmed-up application that can be reused when the same application is restarted, eliminating the need for much of the JIT compilation. • Decoupling the JIT compiler from the JVM for a Cloud environment. Providing a centralised JIT-as-a-Service allows caching of compiled code and offloading the compilation work when new code must be compiled. • Creating a checkpoint of a running application. This includes all application state (heap, stack, etc.) in addition to the JIT-compiled code. Project CRaC will be used as an example. At the end of the session, you’ll be all set to keep your Java hot!
Simon Ritter
Simon Ritter is the Deputy CTO of Azul Systems. Simon has been in the IT business since 1984 and holds a Bachelor of Science degree in Physics from Brunel University in the U.K. Simon joined Sun Microsystems in 1996 and started working with Java technology from JDK 1.0; he has spent time working in both Java development and consultancy. Having moved to Oracle as part of the Sun acquisition, he managed the Java Evangelism team for the core Java platform, Java for client applications and embedded Java. Now at Azul, he continues to help people understand Java as well as Azul’s JVM technologies and products. Simon has twice been awarded Java Rockstar status at JavaOne and is a Java Champion. He currently represents Azul on the JCP Executive Committee and on the Java SE Expert Group (JSR 379, 383 and 384).