The Java 8 specification brings a lot of innovations to the Java platform. Besides new language features such as functional interfaces and Lamda expression support, and library features such as streams and a new date/time API, OpenJDK 8 has a new build system. As this chapter is about building OpenJDK, we will explore the last innovation in depth.

For a long time, the Sun Java and OpenJDK build system grew around the release process. Requirements from the release engineers always came before the developers' requirements, and developers' requirements for the build process differ greatly from release ones. For the release preparation, the build process must be stable. Release builds are usually built from scratch, they always include the whole project and speed, and environment configuration complexities are not issues for them. On the contrary, partial, incremental, and fast as possible builds are required as air for the development. Also, build scripts must be as clean and manageable...