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From Patrick Wendell <>
Subject Re: [VOTE] Designating maintainers for some Spark components
Date Fri, 07 Nov 2014 00:26:56 GMT
Hey Greg,

Regarding subversion - I think the reference is to partial vs full
committers here:

- Patrick

On Thu, Nov 6, 2014 at 4:18 PM, Greg Stein <> wrote:
> -1 (non-binding)
> This is an idea that runs COMPLETELY counter to the Apache Way, and is
> to be severely frowned up. This creates *unequal* ownership of the
> codebase.
> Each Member of the PMC should have *equal* rights to all areas of the
> codebase until their purview. It should not be subjected to others'
> "ownership" except throught the standard mechanisms of reviews and
> if/when absolutely necessary, to vetos.
> Apache does not want "leads", "benevolent dictators" or "assigned
> maintainers", no matter how you may dress it up with multiple
> maintainers per component. The fact is that this creates an unequal
> level of ownership and responsibility. The Board has shut down
> projects that attempted or allowed for "Leads". Just a few months ago,
> there was a problem with somebody calling themself a "Lead".
> I don't know why you suggest that Apache Subversion does this. We
> absolutely do not. Never have. Never will. The Subversion codebase is
> owned by all of us, and we all care for every line of it. Some people
> know more than others, of course. But any one of us, can change any
> part, without being subjected to a "maintainer". Of course, we ask
> people with more knowledge of the component when we feel
> uncomfortable, but we also know when it is safe or not to make a
> specific change. And *always*, our fellow committers can review our
> work and let us know when we've done something wrong.
> Equal ownership reduces fiefdoms, enhances a feeling of community and
> project ownership, and creates a more open and inviting project.
> So again: -1 on this entire concept. Not good, to be polite.
> Regards,
> Greg Stein
> Director, Vice Chairman
> Apache Software Foundation
> On Wed, Nov 05, 2014 at 05:31:58PM -0800, Matei Zaharia wrote:
>> Hi all,
>> I wanted to share a discussion we've been having on the PMC list, as well as call
for an official vote on it on a public list. Basically, as the Spark project scales up, we
need to define a model to make sure there is still great oversight of key components (in particular
internal architecture and public APIs), and to this end I've proposed implementing a maintainer
model for some of these components, similar to other large projects.
>> As background on this, Spark has grown a lot since joining Apache. We've had over
80 contributors/month for the past 3 months, which I believe makes us the most active project
in contributors/month at Apache, as well as over 500 patches/month. The codebase has also
grown significantly, with new libraries for SQL, ML, graphs and more.
>> In this kind of large project, one common way to scale development is to assign "maintainers"
to oversee key components, where each patch to that component needs to get sign-off from at
least one of its maintainers. Most existing large projects do this -- at Apache, some large
ones with this model are CloudStack (the second-most active project overall), Subversion,
and Kafka, and other examples include Linux and Python. This is also by-and-large how Spark
operates today -- most components have a de-facto maintainer.
>> IMO, adopting this model would have two benefits:
>> 1) Consistent oversight of design for that component, especially regarding architecture
and API. This process would ensure that the component's maintainers see all proposed changes
and consider them to fit together in a good way.
>> 2) More structure for new contributors and committers -- in particular, it would
be easy to look up who's responsible for each module and ask them for reviews, etc, rather
than having patches slip between the cracks.
>> We'd like to start with in a light-weight manner, where the model only applies to
certain key components (e.g. scheduler, shuffle) and user-facing APIs (MLlib, GraphX, etc).
Over time, as the project grows, we can expand it if we deem it useful. The specific mechanics
would be as follows:
>> - Some components in Spark will have maintainers assigned to them, where one of the
maintainers needs to sign off on each patch to the component.
>> - Each component with maintainers will have at least 2 maintainers.
>> - Maintainers will be assigned from the most active and knowledgeable committers
on that component by the PMC. The PMC can vote to add / remove maintainers, and maintained
components, through consensus.
>> - Maintainers are expected to be active in responding to patches for their components,
though they do not need to be the main reviewers for them (e.g. they might just sign off on
architecture / API). To prevent inactive maintainers from blocking the project, if a maintainer
isn't responding in a reasonable time period (say 2 weeks), other committers can merge the
patch, and the PMC will want to discuss adding another maintainer.
>> If you'd like to see examples for this model, check out the following projects:
>> - CloudStack:
>> - Subversion: <>
>> Finally, I wanted to list our current proposal for initial components and maintainers.
It would be good to get feedback on other components we might add, but please note that personnel
discussions (e.g. "I don't think Matei should maintain *that* component) should only happen
on the private list. The initial components were chosen to include all public APIs and the
main core components, and the maintainers were chosen from the most active contributors to
those modules.
>> - Spark core public API: Matei, Patrick, Reynold
>> - Job scheduler: Matei, Kay, Patrick
>> - Shuffle and network: Reynold, Aaron, Matei
>> - Block manager: Reynold, Aaron
>> - YARN: Tom, Andrew Or
>> - Python: Josh, Matei
>> - MLlib: Xiangrui, Matei
>> - SQL: Michael, Reynold
>> - Streaming: TD, Matei
>> - GraphX: Ankur, Joey, Reynold
>> I'd like to formally call a [VOTE] on this model, to last 72 hours. The [VOTE] will
end on Nov 8, 2014 at 6 PM PST.
>> Matei
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