[webkit-dev] The tree is on fire: a tragedy of the commons

Xan Lopez xan at gnome.org
Fri Feb 26 01:51:44 PST 2010

On Fri, Feb 26, 2010 at 11:36 AM, Adam Barth <abarth at webkit.org> wrote:
> Not to point fingers, but we've been having trouble keeping
> build.webkit.org green these past few weeks.  As I write this message,
> every platform is broken, again.  As the project scales, polluting the
> build with brokenness impacts more developers and drains more
> productivity.
> Here are some approaches we could use to turn this tragedy of the
> commons around:
> 1) Adopt a "rollout first, ask questions later" ethic.  The vast
> majority of changes are not important enough to break the build for
> everyone else.  If we adopt a "rollout first, ask questions later"
> ethic, committers would feel free to rollout brokenness to unbreak the
> build and contributors shouldn't be offended if their patch is rolled
> out without their knowledge.  We can always re-land the broken patch
> later once it actually works.

In my experience this is more or less the current policy, especially
for build breakage (as opposed to test breakage). Maybe a bit less
hardliner in that we usually try contact the culprit and give some
time to fix issues, but I think there's no remorse in rolling out
patches if there's brokenness and nobody working on fixing it.

> 2) Require pre-commit vetting of patches.  We have the resources to
> build and test every patch on at least one platform before landing the
> patch in the main tree.  Vetting patches before landing will help us
> avoid breaking every platform at once.  Once the patch has been
> vetted, it can either be landed mechanically (i.e., by commit-queue)
> or manually.
> Here's how I would design the life and times of a patch:
> 1) Contributor uploads patch and nominates it for review.
> 2) Patch vetted by the EWS on numerous platforms.
> 3) If the EWS finds a problem, return to step 1.
> 4) Reviewer marks patch review+.
> 5) Committer decides the patch is ready to land.
> 6) Patch built and tested against top-of-tree on at least one platform.
> 7) If the patch fail to build or pass tests, return to step 1.
> 8) Patch landed.
> 9) If the patch turns any of the "core builders" red, patch is rolled
> out, return to step 1.

EWS has been a huge boon in productivity at least for us GTK+ folks,
so I fully support any step to increase its awesomeness! Of course
what we need to do is to work on increasing the number of "core
builders", but that's an orthogonal issue and our own responsibility.



> I suspect most of our brokenness coming from committers skipping steps 6 and 7.
> Adam
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