[Python-Dev] How to watch buildbots?
On 30.05.2018 16:36, Nick Coghlan wrote:
> On 30 May 2018 at 22:30, Ivan Pozdeev via Python-Dev
> <python-dev at python.org <mailto:python-dev at python.org>> wrote:
> What's the big idea of separate buildbots anyway? I thought the
> purpose of CI is to test everything _before_
> it breaks the main codebase. Then it's the job of the contributor
> rather than maintainer to fix any breakages.
> So, maybe making them be driven by Github checks would be a better
> time investment.
> Especially since we've got VSTS checks just recently, so whoever
> was doing that still knows how to interface with this Github
> If the bots cancel a previous build if a new one for the same PR
> arrives, this will not lead to a significant load difference 'cuz
> the number of
> actively developed PRs is stable and roughly equal to the number
> of merges according to the open/closed tickets dynamics.
> There are a few key details here:
> 1. We currently need to run post-merge CI anyway, as we're not doing
> linearised commits (where core devs just approve a change without
> merging it, and then a gating system like Zuul ensures that the tests
> are run against the latest combination of the target branch and the PR
> before merging the change)
This is the only point here that looks valid (others can be refuted).
This technique limits the achievable commit rate by 1/testing_time . Our
average rate probably fits into this, though it still means delays.
> 2. Since the buildbots are running on donated dedicated machines
> (rather than throwaway instances from a dynamic CI provider), we need
> to review the code before we let it run on the contributed systems
> 3. The buildbot instances run *1* build at a time, which would lead to
> major PR merging bottlenecks during sprints if we made them a gating
> 4. For the vast majority of PRs, the post-merge cross-platform testing
> is a formality, since the code being modified is using lower level
> cross-platform APIs elsewhere in the standard library, so if it works
> on Windows, Linux, and Mac OS X, it will work everywhere Python runs
> 5. We generally don't *want* to burden new contributors with the task
> of dealing with the less common (or harder to target) platforms
> outside the big 3 - when they do break, it often takes a non-trivial
> amount of platform knowledge to understand what's different about the
> platform in question
> P.S. That said, if VSTS or Travis were to offer FreeBSD as an option
> for pre-merge CI, I'd suggest we enable it, at least in an advisory
> capacity - it's a better check against Linux-specific assumptions
> creeping into the code base than Mac OS X, since the latter is
> regularly different enough from other *nix systems that we need to
> give it dedicated code paths.
> Nick Coghlan?? | ncoghlan at gmail.com <mailto:ncoghlan at gmail.com> |??
> Brisbane, Australia
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