The OpenJDK Quality Group is promoting the testing of FOSS projects with OpenJDK builds as a way to improve the overall quality of the release. This heads-up is part of a regular communication sent to the projects involved. To learn more about the program, and how-to join, please check here.

On The Importance of Testing With Early-Access Build

The following is a recent example that demonstrates the benefits of testing an existing codebase using the OpenJDK early-access builds.

Last month, we published a heads-up focused on Sequenced Collections as they could potentially introduce some incompatibilities.

The Eclipse Collections (EC) team did their homework and sure enough, EC was impacted as it was now throwing compilation errors with JDK 21 early-access builds. The EC team was able to quickly fix those compilation errors, i.e., it was mainly about adding overriding default methods. But once those compilation errors were fixed, and this is where it gets interesting, another issue surfaced. This time, the problem was related to LinkedHashMap serialization. After some investigation, the EC team identified that second issue as JDK one and a JBS ticket was opened. That issue was then confirmed as a JDK regression and was promptly fixed in OpenJDK main-line, i.e., JDK 22. The fix was then backported into the JDK 21 stabilization repository. This EC pull request provides additional details.

In this case, the JDK fix was easy but it is nevertheless the kind of issues that could have easily fallen through the crack if the EC team wasn’t pro-actively testing with OpenJDK early-access builds. The EC issue would have then surfaced after the JDK 21 General Availability… and who knows when the JDK LinkedHashMap serialization regression would have been fixed?

TL; DR. Testing an existing codebase with OpenJDK early-access builds is a win-win situation. It helps the project itself, Eclipse Collections in this case, as it enables developers to identify issues in their own codebase before that new JDK version is Generally Available. It helps the JDK too as any JDK issue detected early enough in the development cycle gives the OpenJDK engineers a chance to address it before the General Availability of that new JDK version. And last but not least, having a robust JDK is also a win for the Java community at large.

And thanks to the Eclipse Collections team and especially to Donald Raab for helping to make the Java platform more robust!

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