[Python-Dev] release cadence (was: Request for CPython 3.5.3 release)

Brett Cannon brett at python.org
Sun Jul 3 17:48:27 EDT 2016

I actually thought about Rust when thinking about 3 month releases (I know
they release faster though). What i would want to know is whether the RMs
for Rust are employed by Mozilla and thus have work time to do but it vs
Python RMs & friends who vary ob whether they get work time.

On Sun, Jul 3, 2016, 13:54 Chris Krycho <chris at chriskrycho.com> wrote:

> As an observer and user—
> It may be worth asking the Rust team what the main pain points are in
> coordinating and managing their releases.
> Some context for those unfamiliar: Rust uses a Chrome- or Firefox-like
> release train approach, with stable and beta releases every six weeks. Each
> release cycle includes both the compiler and the standard library. They use
> feature flags on "nightly" (the master branch) and cut release branches for
> actually gets shipped in each release. This has the advantage of letting
> new features and functionality ship whenever they're ready, rather than
> waiting for Big Bang releases. Because of strong commitments to stability
> and backwards compatibility as part of that, it hasn't led to any
> substantial breakage along the way, either.
> There is also some early discussion of how they might add LTS releases
> into that mix.
> The Rust standard library is currently bundled into the same repository as
> the compiler. Although the stdlib is currently being modularized and
> somewhat decoupled from the compiler, I don't believe they intend to
> separate it from the compiler repository or release in that process (not
> least because there's no need to further speed up their release cadence!).
> None of that is meant to suggest Python adopt that specific cadence
> (though I have found it *quite* nice), but simply to observe that the
> Rust team might have useful info on upsides, downsides, and particular
> gotchas as Python considers changing its own release process.
> Regards,
> Chris Krycho
> On Jul 3, 2016, at 16:22, Brett Cannon <brett at python.org> wrote:
> [forking the conversation since the subject has shifted]
> On Sun, 3 Jul 2016 at 09:50 Steve Dower <steve.dower at python.org> wrote:
>> Many of our users prefer stability (the sort who plan operating system
>> updates years in advance), but generally I'm in favour of more frequent
>> releases.
> So there's our 18 month cadence for feature/minor releases, and then
> there's the 6 month cadence for bug-fix/micro releases. At the language
> summit there was the discussion kicked off by Ned about our release
> schedule and a group of us had a discussion afterward where a more strict
> release cadence of 12 months with the release date tied to a consistent
> month -- e.g. September of every year -- instead of our hand-wavy "about 18
> months after the last feature release"; people in the discussion seemed to
> like the 12 months consistency idea. I think making releases on a regular,
> annual schedule requires simply a decision by us to do it since the time
> scale we are talking about is still so large it shouldn't impact the
> workload of RMs & friends *that* much (I think).
> As for upping the bug-fix release cadence, if we can automate that then
> perhaps we can up the frequency (maybe once every quarter), but I'm not
> sure what kind of overhead that would add and thus how much would need to
> be automated to make that release cadence work. Doing this kind of shrunken
> cadence for bug-fix releases would require the RM & friends to decide what
> would need to be automated to shrink the release schedule to make it viable
> (e.g. "if we automated steps N & M of the release process then I would be
> okay releasing every 3 months instead of 6").
> For me, I say we shift to an annual feature release in a specific month
> every year, and switch to a quarterly bug-fix releases only if we can add
> zero extra work to RMs & friends.
>> It will likely require more complex branching though, presumably based on
>> the LTS model everyone else uses.
> Why is that? You can almost view our feature releases as LTS releases, at
> which point our current branching structure is no different.
>> One thing we've discussed before is separating core and stdlib releases.
>> I'd be really interested to see a release where most of the stdlib is just
>> preinstalled (and upgradeable) PyPI packages. We can pin versions/bundle
>> wheels for stable releases and provide a fast track via pip to update
>> individual packages.
>> Probably no better opportunity to make such a fundamental change as we
>> move to a new VCS...
> <deep breath />
> Topic 1
> =======
> If we separate out the stdlib, we first need to answer why we are doing
> this? The arguments supporting this idea is (1) it might simplify more
> frequent releases of Python (but that's a guess), (2) it would make the
> stdlib less CPython-dependent (if purely by the fact of perception and ease
> of testing using CI against other interpreters when they have matching
> version support), and (3) it might make it easier for us to get more
> contributors who are comfortable helping with just the stdlib vs CPython
> itself (once again, this might simply be through perception).
> So if we really wanted to go this route of breaking out the stdlib, I
> think we have two options. One is to have the cpython repo represent the
> CPython interpreter and then have a separate stdlib repo. The other option
> is to still have cpython represent the interpreter but then each stdlib
> module have their own repository.
> Since the single repo for the stdlib is not that crazy, I'll talk about
> the crazier N repo idea (in all scenarios we would probably have a repo
> that pulled in cpython and the stdlib through either git submodules or
> subtrees and that would represent a CPython release repo). In this
> scenario, having each module/package have its own repo could get us a
> couple of things. One is that it might help simplify module maintenance by
> allowing each module to have its own issue tracker, set of contributors,
> etc. This also means it will make it obvious what modules are being
> neglected which will either draw attention and get help or honestly lead to
> a deprecation if no one is willing to help maintain it.
> Separate repos would also allow for easier backport releases (e.g. what
> asyncio and typing have been doing since they were created). If a module is
> maintained as if it was its own project then it makes it easier to make
> releases separated from the stdlib itself (although the usefulness is
> minimized as long as sys.path has site-packages as its last entry).
> Separate releases allows for faster releases of the stand-alone module,
> e.g. if only asyncio has a bug then asyncio can cut their own release and
> the rest of the stdlib doesn't need to care. Then when a new CPython
> release is done we can simply bundle up the stable release at the moment
> and essentially make our mythical sumo release be the stdlib release itself
> (and this would help stop modules like asyncio and typing from simply
> copying modules into the stdlib from their external repo if we just pulled
> in their repo using submodules or subtrees in a master repo).
> And yes, I realize this might lead to a ton of repos, but maybe that's an
> important side effect. We have so much code in our stdlib that it's hard to
> maintain and fixes can get dropped on the floor. If this causes us to
> re-prioritize what should be in the stdlib and trim it back to things we
> consider critical to have in all Python releases, then IMO that's as a huge
> win in maintainability and workload savings instead of carrying forward
> neglected code (or at least help people focus on modules they care about
> and let others know where help is truly needed).
> Topic 2
> =======
> Independent releases of the stdlib could be done, although if we break the
> stdlib up into individual repos then it shifts the conversation as
> individual modules could simply do their own releases independent of the
> big stdlib release. Personally I don't see a point of doing a stdlib
> release separate from CPython, but I could see doing a more frequent
> release of CPython where the only thing that changed is the stdlib itself
> (but I don't know if that would even alleviate the RM workload).
> For me, I'm more interested in thinking about breaking the stdlib modules
> into their own repos and making a CPython release more of a collection of
> python-dev-approved modules that are maintained under the python
> organization on GitHub and follow our compatibility guidelines and code
> quality along with the CPython interpreter. This would also make it much
> easier for custom distros, e.g. a cloud-targeted CPython release that
> ignored all GUI libraries.
> -Brett
>> Cheers,
>> Steve
>> Top-posted from my Windows Phone
>> ------------------------------
>> From: Guido van Rossum <guido at python.org>
>> Sent: ‎7/‎3/‎2016 7:42
>> To: Python-Dev <python-dev at python.org>
>> Cc: Nick Coghlan <ncoghlan at gmail.com>
>> Subject: Re: [Python-Dev] Request for CPython 3.5.3 release
>> Another thought recently occurred to me. Do releases really have to be
>> such big productions? A recent ACM article by Tom Limoncelli[1]
>> reminded me that we're doing releases the old-fashioned way --
>> infrequently, and with lots of manual labor. Maybe we could
>> (eventually) try to strive for a lighter-weight, more automated
>> release process? It would be less work, and it would reduce stress for
>> authors of stdlib modules and packages -- there's always the next
>> release. I would think this wouldn't obviate the need for carefully
>> planned and timed "big deal" feature releases, but it could make the
>> bug fix releases *less* of a deal, for everyone.
>> [1]
>> http://cacm.acm.org/magazines/2016/7/204027-the-small-batches-principle/abstract
>> (sadly requires login)
>> --
>> --Guido van Rossum (python.org/~guido)
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