The work to create OpenJDK/JDK7 Mercurial repositories is progressing, but before I tell you anything significant, I'll bore you with some basic details about JDK building. ;^)

JDK Build Promotions

First, let me explain a little about the JDK build promotions. The build promotion cycle for active releases is usually 1 or 2 weeks long, and currently for JDK7 it's 2 weeks. That means that roughly every 2 weeks, a promoted JDK7 build is made available at the jdk7.dev.java.netbinary bundle area (plus the JRL source bundle area), and also at the OpenJDK.java.net source bundle area. I assume people see the emails sent out on promotions to the announce@openjdk.java.net alias (subscribe at the openjdk mailing lists site).

Between promotions, individuals integrate their JDK7 changes into the various team integration areas, and the teams will then integrate their changes into the MASTER JDK7 source workspaces. The MASTER source workspaces are like the Pacific Ocean, with all the various teams sending their changes to the MASTER repositories like water flowing through the various rivers, lakes, etc. into the Pacific. At any point the changes might get held up or inspected by a "gate keeper" or "integrator", like the dam operators on rivers (that's "dam operators", not "damn operators"). Ok ok, strange analogy, but it kind of fits. In any case, sometimes a change looks like it might make it into the MASTER workspaces and into a build promotion, but it doesn't, some gate keeper might scoop it out of the river, or some bear might drink it or something (some bears might also make contribution to the river, but let's not go there, most of the pesky bears have been relocated north of here). Ultimately if a change doesn't make a promotion and isn't permanently diverted, it will make the next promotion, or the one after that, just depends on how far it has to go. (And yes, testing is part of this process, the water is indeed safe to drink).

The schedule for when build promotions will happen is fairly predictable, but anything can happen, and sometimes they get delayed. The current schedule is... HA, you thought I was going to give you hard dates! ... well ok, why not, but these are estimated dates, and sometimes you need to add a day to the final promotion day before the actual bundles are available on the jdk7.dev.java.net and openjdk.java.net sites:

  • JDK7 Build 19 final - estimated Aug 31
  • JDK7 Build 20 final - estimated Sept 14
  • JDK7 Build 21 final - estimated Sept 28
  • JDK7 Build 22 final - estimated Oct 12
  • JDK7 Build 23 final - estimated Oct 26

If a build slips, all the following build promotion dates have to be permanently adjusted. These build promotion dates are probably no big surprise, anyone could look at the past delivery of JDK7 build promotions and guessed this much. But I wanted to attach at least some preliminary dates to some build numbers so you understand the planning a bit.

Note that once we get into delivering Mercurial repositories, the whole "time frame" as to when you see source changes is drastically different. The traditional source bundles become less interesting, except for maybe archiving. And even after Mercurial, the JDK Build Promotions will continue, and the binary bundles and all deliveries to jdk7.dev.java.net won't change much.

The "langtools" Separation

Second, hopefully in Build 19 (backup plan is Build 20) we will be doing some major restructuring of the j2se workspace. This first restructuring is called the "langtools" separation. The "langtools" are the tools javac, javah, javap, javadoc, and apt. This change is significant because it removes the fairly complicated javac "recompile" cycle from the j2se build, and greatly simplifies the j2se build (many Makefiles get deleted). It introduces another tree of sources (about 3,000 files) with the name "langtools".

No, it doesn't mean the entire j2se build can convert to ant.

Other Changes

Third, in Builds 20 through 22 or 22, there may be additional restructurings and things like SCCS keyword removals.

The Transition

Lastly, we sincerely hope that Build 22 or 23 will be the last promotion built with TeamWare sources, meaning that at some point after those promotions we can start working on making the OpenJDK repositories available, probably fairly quickly in terms of a read-only state.

Mercurial Transition Details

Just to make sure people are aware of some of the technical details of how the transformation will happen:

  • A Set of Repositories 

    Keep in mind that we are talking about a set of repositories, not just one. The current repository set is: control, langtools, j2se, and hotspot. A one-to-one mapping from the TeamWare workspaces to the Mercurial repositories will be maintained at transition time. (Although we had plans for a Mercurial forest, and may use them eventually, for now the OpenJDK repositories will likely just be a set of separate repositories).

    And more important, we are probably talking many different sets of repositories, one set for the MASTER repositories which are read-only to everyone except the gate keepers or integrators, plus potentially a set of repositories for each of the team integration areas. The specific details remains to be seen. With a DSCMsystem like Mercurial or TeamWare, you usually end up with the Ocean and rivers analogy I mentioned above, with changes trickling in over time, from various team integration areas. Just looking at the MASTER level may be appropriate for some, but for others, particular team integration areas may be of more interest. The patterns we have used over the years with TeamWare will map pretty much the same way to Mercurial.

  • History of Past Changes 

    No past history of the sources will be included (for legal reasons we can't provide history prior to the launch, and for technical reasons we decided to not provide the TeamWare history between the launch and the transition). Effectively each file will be 'sccs edit'd out of the TeamWare workspace, and added to a Mercurial repository.

Conclusion

Hope this was helpful. This project has been extremely hard to predict, and I'm still not sure that some evil issue won't de-rail the plans, but hopefully this keeps you all informed.

It will be over soon, I hope, as you can tell from my writing I'm getting a little dingy (no I'm not getting a small boat). ;^)

-kto