Preface

OpenJDK is a unique project that opens numerous and exciting opportunities for people who want to dive into the huge and complicated infrastructure behind the JVM. There is an incredible amount of things to learn and to explore. Almost anyone can find something in it as per their interest, starting from HTTP, Web, software dependency problems, and ending with hardware-specific JIT optimization techniques, and concurrency challenges. Such variety is very unique and it would be true to say that there is no other open source project that can provide something similar. The other factor is that there are not so many other open source projects on that scale; possibly only the Linux core. Such scale requires a non-trivial organizational approach and, to be involved in that process, to see how it works, is a very interesting insight.

This cookbook will lead you through steps to take you into the world of OpenJDK as smoothly as possible. It starts by explaining how to download the source code and how to build the different versions of OpenJDK, how to set it up on a machine, and what different options are available. Then, you will learn how to set up the development environment (IDE) required for editing and debugging C++ and Java source code, and how to start making changes. It will go through some examples, which you may decide to change in various parts of OpenJDK. Further, it will cover the tools available for testing, benchmarking, and ensuring that the changes you have made are not breaking the existing functionality. As OpenJDK is a big project with its own rules and processes, there will be a part covering the procedures that are involved in making changes or fixing bugs, the lifecycle of projects, JSRs, JEPs, and so on. At the end, there will be a section about future work that is planned to be included in forthcoming releases; that part will be the most interesting section for anyone who is interested in the future direction of OpenJDK and wants to try something new, which is not yet available in the stable product.

In addition, this book contains many practical examples which should be useful to any developer who is working with OpenJDK or any other Java technology. They are available in simple form, which allows you to quickly copy and use them for your own project.