openj9

Java Licensing: If you want to pay for a supported Java, with long term ongoing patches: call a commercial vendor of Java such as Oracle, Azul Systems, etc. If you want a free and open source Java runtime, use Open JDK. Some sources of OpenJDK pledge to backport bug fixes from newer versions for some number of years. Or you can simply make sure your product continues to run on newer versions -- which for Java, according to history, has been easy to do. Where to get Open JDK: Adopt Open JDK https://adoptopenjdk.net/ https://github.com/AdoptOpenJDK https://github.com/ojdkbuild/ojdkbuild Open JDK http://openjdk.java.net/ Azul Systems Zulu http://www.azul.com/downloads/zulu/ Amazon https://aws.amazon.com/fr/corretto/ https://github.com/corretto Eclipse https://www.eclipse.org/openj9/ https://adoptopenjdk.net/releases.html?variant=openjdk11

The IBM J9 JVM was open sourced and now lives as the Eclipse OpenJ9 project [1]. We rely on interpreter profiling (block frequency, and value profiling) before the JIT gets it's hands on the method. Once the JIT has determined the cost/benefit is right for a JIT compile we will run through an extended basic block ordering optimization which will lay out the code by block frequency calculated from the taken vs. not taken profiling information on the branch bytecodes given to us by the interpreter. The persistence portion you mention between runs is our AOT capability in which we are able to cache JIT method compilations on disk and load them between different JVM invocations to greatly speed up startup performance. There is a recent series of blog posts on the AOT technology in OpenJ9 in [2]. [1] https://github.com/eclipse/openj9 [2] https

This method of design is called a Continuation Passing Style Interpreter. [1] Here's a production version from OpenJ9's JVM ByteCode Interpreter. [2] [1] https://kseo.github.io/posts/2017-01-09-continuation-passing... [2] https://github.com/eclipse/openj9/blob/01be53f659a8190959c16...