Call for Discussion: New Project: Skara -- investigating source code management options for the JDK sources

Patrick Reinhart patrick at
Sat Jul 28 19:11:17 UTC 2018

Hi Mario,

I’ve now contributed a couple of changes to the JDK now and for me as a part time contributor. It would be much easier for me, to have used git instead of mercurial, due the fact that I use git on a daily basis. and its commands for creating different feature branches and handling patches would be easier for me.

Nevertheless I it is important in my opinion that git and the Github process are two separate things. I would fear to have the JDK on Github just due to the fact you might get flooded with a huge amount of pull requests for things not actually discussed on any mailing list before and the existing reviewers would not be able to keep up.

I would like to see a improvement and better support in handling contributions and the review process in general as using the webrev tool as it is now. In that regard the review process on github using a separate feature branch on a clone seems a good start...


> Am 27.07.2018 um 11:26 schrieb Mario Torre <neugens at>:
> Hi Martijn,
> How many contributions from developers in those git mirrors came into
> OpenJDK (or even, how many contributions happened on those mirrors
> outside of OpenJDK development?).
> I think the point about performance is sound [1], but I would be very
> careful to introduce a new SCM, lots of developers are used with
> mercurial now, and even if git is probably just a small learning step
> away, I would argue that this is unnecessary to the people who are
> already contributing.
> What are the actual benefit for this change? I mean, yes, the list of
> evaluation criteria, but in practice, why do we need to change?
> I don't think the remote possibility of attracting a few more people
> is an answer, the current work flow is simple enough, while the
> biggest barrier is the process, not the SCM. I doubt we want to change
> the process (and I'm not advocating this either!), so the benefit to
> go git (unless you mean we're exploring svn or cvs!!) seems limited
> compared to the overhead.
> I may be just too old school, but I think we should be investing the
> energies somewhere else.
> Cheers,
> Mario
> [1] It really is terrible now with a single repo, but is it a problem
> of mercurial really? Git also carries all the history in the clone,
> did somebody do some testing on this, and I mean, on the same servers
> and network?
> On Fri, Jul 27, 2018 at 10:31 AM, Martijn Verburg
> <martijnverburg at> wrote:
>> Hi Joe,
>> The Adoption group has been having a lot of ‘fun’ with importing hg into
>> git (one of the options that you’ll likely explore) for our git mirrors.
>> We’ve got a bunch of war stories and most importantly working scripts that
>> capture history and tags and all that good stuff.  They’re Apache 2
>> licensed at the moment but I’m sure the authors (all being Adoption
>> members) will be happy to re license or dual license.
>> Other useful knowledge we can share is around how we manage repos,
>> projects, issues, work in progress and code reviews at the Adopt build
>> farm. We’ve learned some valuable lessons of what works and what doesn’t at
>> a reasonable scale of number of contributors around a git based workflow.
>> Assuming this project kicks off We’re all very happy to help out!
>> Cheers,
>> Martijn
>> On Fri, 27 Jul 2018 at 05:13, joe darcy <joe.darcy at> wrote:
>>> Hello,
>>> The source code management (SCM) system of a software project is a
>>> fundamental piece of its infrastructure and workflows. Starting in
>>> February 2008, the source code of different JDK releases and supporting
>>> projects has been hosted in Mercurial repositories under
>>> Code reviews of JDK changes are typically
>>> conducted as discussions in mailing lists over small patches sent to one
>>> or more lists or over webrevs hosted on Since 2008,
>>> many open source projects have successfully adopted more efficient SCM
>>> and review tooling, in some cases provided by third parties.
>>> In order to help OpenJDK contributors be more productive, both seasoned
>>> committers and relative newcomers, the Skara project proposes to
>>> investigate alternative SCM and code review options for the JDK source
>>> code, including options based upon Git rather than Mercurial, and
>>> including options hosted by third parties.
>>> The Skara project intends to build prototypes of hosting the JDK 12
>>> sources under different providers.
>>> The evaluation criteria to consider include but are not limited to:
>>>     * Performance: time for clone operations from master repos, time of
>>> local operations, etc.
>>>     * Space efficiency
>>>     * Usability in different geographies
>>>     * Support for common development environments such as Linux, Mac,
>>> and Windows
>>>     * Able to easily host the entire history of the JDK and the
>>> projected growth of its history over the next decade
>>>     * Support for general JDK code review practices
>>>     * Programmatic APIs to enable process assistance and automation of
>>> review and processes
>>> If one or more prototypes indicate a different SCM arrangement offers
>>> substantial improvements over the current situation, the Skara project
>>> will shepherd a JEP to change the SCM for the JDK.
>>> I propose to lead the project with the initial reviewers including but
>>> not limited to Tim Bell (tbell), Erik Duveblad (ehelin), Erik Joelsson
>>> (erikj), Tiep Vo (tiep), Tony Squier (squierts), and Robin Westberg
>>> (rwestberg).
>>> We suggest the build group sponsor this work.
>>> Changing the bug tracking system is out of scope for this project and is
>>> *not* under consideration.
>>> Comments?
>>> Cheers,
>>> -Joe
>>> --
>> Cheers, Martijn (Sent from Gmail Mobile)
> --
> Mario Torre
> Associate Manager, Software Engineering
> Red Hat GmbH <>
> 9704 A60C B4BE A8B8 0F30  9205 5D7E 4952 3F65 7898

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