The makefiles for the OpenJDK have begun to show their age. They were slow, did not allow for incremental builds, and created a high barrier of entry for new Java developers who wanted to join the OpenJDK development community.
It took one year to achieve, but now the new makefiles are in the OpenJDK and the build times have been reduced by a factor of 5 and support efficient incremental builds. This presentation explains and demonstrates the new makefiles and how you can put this new technology to use in your own projects.