Jigsaw Issues Delay Java 9 Release (Again), But EC Concerns Addressed

Although he wants to continue pushing for a June 22 Release Candidate build, Mark Reinhold has announced a Sept. 21 General Availability release for the JDK 9 project. That's eight weeks past the previously scheduled July 27 GA release, which is going to be frustrating for many in the Java community. But there is reason to hope that this will be the final delay.

The holdup, as anyone who has been following the painfully slow crawl toward Java 9 knows, is mostly about JSR 376, the Java Platform Module System (JPMS) specification, better known as Jigsaw. Reinhold, the chief architect of Oracle's Java Platform Group, proposed two earlier delays, both times citing the challenges posed by Project Jigsaw.

But a vote in May by the Executive Committee (EC) of the Java Community Process (JCP) to reject JSR 376 seems to have sparked a real fire under the Expert Group, which met via video conference last month to address the EC's concerns about the current state of the project. Their goal was to submit a revised Public Review Draft Specification by June 7. The Public Review Reconsideration Ballot is now underway; voting ends on June 26.

The minutes of the Expert Group meeting are available now online, and they're well worth reading. In a nutshell, the EG worked out which issues raised by the EC during the first Public Review would need to be worked out now, which ones could wait for later, and which ones could wait forever. Several issues had already been sorted -- the EG wasn't sitting on its hands -- and several more were resolved at this meeting.

"I think it's fair to say that people were highly motivated to reach closure on all of these issues," Georges Saab, VP of Development for Oracle's Java SE Group, told me. "Meeting directly made a real difference, I think. Sitting down together allowed them to make more rapid progress."

Reinhold brought two "new information" items to the meeting: a proposal to allow illegal reflective access by default in JDK 9, and a proposal he's been talking about at conferences for a more rapid release cadence for Java SE and the JDK.

In her minutes, Iris Clark summarized the first item this way: "As more and more people have tested JDK 9 EA builds it has become clear in wide discussions over the past few months that turning off reflective access from code on the class path is too aggressive for the initial release. The proposal is to allow this access by default in JDK 9, and disallow it in a future release. A warning will be issued on the first access. This proposal will not address all migration concerns, but it changes the migration from one huge step to multiple smaller steps spread across multiple releases. This proposal is technically not part of JSR 376, since 376 is just about the module system; it is part of the JSR 379 platform specification, which will contain the necessary conformance text."

The second item, the idea that the Java ecosystem would benefit from more rapid releases, has been floating around Oracle and the JCP for a while. Clark summarized Reinhold's explanation this way: "Since the inception of Java, big features or a handful of big features have driven major releases every two to three years. This was reasonable in the 1990's and 2000's. Going forward, Java needs to move at a faster pace in order to remain competitive. People are, therefore, exploring the possibility of shifting to a yearly or even a six-month cycle. If a big feature is ready, it goes in; otherwise, it waits for the next release."

There's no formal proposal to crank up the Java release cadence right now, but it's coming, and, as Saab pointed out, the technology causing so many delays right now is probably going to be a key enabler going forward.

"The good news is, the Java Platform Module System and the encapsulation it ultimately provides, gives us a sound basis for doing that without disrupting people with the fears of incompatibility they would have had in the past," Saab said. "It makes it much clearer what the API is you should depend on, and it makes it far easier to test and confirm that you have the compatibility you want as you're doing those more rapid revs."

Reinhold published the new release schedule on the JDK 9 project page. Here's how it currently stands:

Posted by John K. Waters on June 14, 2017