[11u] Proposal: Switch jdk11u development to Git/Skara with 11.0.13 cycle

[Langer, Christoph]

Hi Andrew,

you have valid concerns which I hope we can get sorted out until the proposed 11u switch. Let me answer in detail:

> I have still not seen any answer to my question of how a bulk update is
> pushed for the CPU.

I think generally this is kind of answered. For the 11u <-> 11u-dev merges we can use a facility called "Merge PR", something like people used to merge jdk16 back into jdk [0].
Although I've not yet done it myself and will need to talk to Skara folks to get it explained better, I think this is what we can use.

For working on the CPU I hope to be able to use "git bundle" to distribute the state of work on vuln-dev (Similar to what we do with hg bundle now) and eventually push the release via a Merge PR. I will explore this in detail in the next weeks and see if it's bound to work. In case I don't see it working, I'd consider it a showstopper. So I'll update you on this soon, in time before the advised github switch.

> My own attempts to backport to jdk13u suggest the tooling still needs
> work on this, or at least better documentation. [0]

I think you have a point here. As far as I know the "git backport" command does not exist yet and also the process to backport a change by commenting "/backport" on the original change in the jdk repository is not activated yet. I've brought this up to the skara team and they said that they hope to be able to enable it soon [1]. At the moment a backport would work like documented in the manual steps of this link [2] - which is not too convenient. I'll approach Skara folks again about that.

> OpenJDK 16, the first release to use git during development, has not
> even been released yet. Why the rush?

Well, I would not consider it to be in a rush, given the proposal of switching in about 4 months from now. But overall, to align processes, to me it seems favorable to go to git with 11u and we should not overly delay it. At that time JDK16 and its first update release 16.0.1 will have been delivered out of git (as well as a few jdk13u update releases).

> I don't see any reason at all to start altering 8u at such a late
> stage in its development.  All risk and no gain.

That's a different discussion which I won't take part in as I'm not involved so much in 8u. The only point I have on that is that there's no reason to couple the decisions for 8 and 11, as was stated by Severin and Goetz already.

Best regards
Christoph

[0] https://github.com/openjdk/jdk/pull/2392
[1] https://mail.openjdk.java.net/pipermail/skara-dev/2021-January/004051.html
[2] https://wiki.openjdk.java.net/display/SKARA/Backports#Backports-CLI