[llvm-dev] [RFC] Python 2 / Python 3 status, final step(s)

Fri Dec 18 00:11:24 PST 2020

Thanks Reid for taking this risky step. As someone who just lost one day
upgrading/downgrading/messing up its laptop, I fully appreciate the risk
you took, and I'm glad everything looks fine.

The two slaves I had issues whith were:

    http://lab.llvm.org:8011/#/builders/127 (now green)
    http://lab.llvm.org:8011/#/workers/14 (now green)

Thanks a bunch!

> As a long suffering maintainer

And extra thanks for the maintenance task too o/

On Thu, Dec 17, 2020 at 9:19 PM Reid Kleckner <rnk at google.com> wrote:

> Nevermind. I went ahead and took the risk of installing Python 3 and
> putting it on PATH, and the buildbot service code seems to be working as
> is. Both bots have made it past cmake, so they're probably on track to
> recover.
>
> On Thu, Dec 17, 2020 at 11:38 AM Reid Kleckner <rnk at google.com> wrote:
>
>> Can we delay this? I maintain two Windows buildbots, and I'm about to go
>> on holiday break, and I'd really rather not scramble to get them up to date:
>> http://lab.llvm.org:8011/#/builders/clang-x64-windows-msvc
>> http://lab.llvm.org:8011/#/builders/sanitizer-windows
>>
>> Looking at them now, it seems you broke them five hours ago.
>>
>> There is risk involved in simply installing Python 3, since it might
>> necessitate upgrading the buildbot worker version, which I have
>> successfully avoided doing for almost five years now.
>>
>> This has not been a good month for Windows bots. As a long suffering
>> maintainer, I'm asking for a reprieve.
>>
>> On Mon, Dec 14, 2020 at 10:30 PM Serge Guelton via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hi Folks,
>>>
>>> unless someone has strong arguments against it, the transition to Python
>>> 3 will happen *this week*, on Thursday morning, european time.
>>> The associated review is https://reviews.llvm.org/D93097, feel free to
>>> drop in.
>>> The impact should be low, Python3 is already picked by CMake as default,
>>> but a Python 2 fallback still exists, and it will be removed.
>>>
>>> **If you're a bot owner** please make sure Python3 is available on your
>>> system ! Now, is the time :-)
>>>
>>> On Mon, Oct 19, 2020 at 9:34 PM Jonas Devlieghere via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>>> Sounds good. In LLDB we have a slightly different timeline for the test
>>>> suite (outlined in
>>>> http://lists.llvm.org/pipermail/lldb-dev/2020-August/016388.html) but
>>>> everything else aligns with the plan here. I already removed the fallback
>>>> to Python 2 in preparation for the 12.0 release.
>>>>
>>>> On Tue, Oct 13, 2020 at 11:49 AM David Blaikie via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>>> *thumbs up*
>>>>>
>>>>> Re: out of date buildbots: maybe stage the shebang changes in a
>>>>> time/way that's easy to rollback (or even intended to rollback after a
>>>>> small time window (few hours) off-peak) to flush out the buildbots. Then
>>>>> after that rollout, go over the buildbot failures and follow-up with
>>>>> buildbot owners to get them cleaned up before a more intended-to-stick
>>>>> rollout is done.
>>>>>
>>>>> On Tue, Oct 13, 2020 at 7:18 AM James Y Knight via llvm-dev <
>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>
>>>>>> Yay, thanks for persevering with this migration!
>>>>>>
>>>>>> On Tue, Oct 13, 2020 at 8:04 AM Serge Guelton via llvm-dev <
>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>> Hi Folks,
>>>>>>>
>>>>>>> Now that LLVM 11.0.0 has been released, it's time to prepare for the
>>>>>>> final step
>>>>>>> envisionned in the previous RFC named *[RFC] Python 2 / Python 3
>>>>>>> status* [0],
>>>>>>> ie. requiring Python3.6 for LLVM 12.0.0, to be released in 2021.
>>>>>>> At least Fedora already only ships Python3 and we didn't have much
>>>>>>> bugs reported
>>>>>>> wrt. Python compatibility for the LLVM toolchain.
>>>>>>>
>>>>>>> Indeed, all Python scripts should now be at least compatible with
>>>>>>> both python2 (py2)
>>>>>>> and python3 (py3), some of them already are already py3 only.
>>>>>>>
>>>>>>> The build system still depends on Python in a few place, but it
>>>>>>> explicitly
>>>>>>> mentions Python3_EXECUTABLE, and the main dependency (llvm-build) is
>>>>>>> currently
>>>>>>> being removed  in D89142.
>>>>>>>
>>>>>>> The shebangs have already been harmonized in D83857: some mention
>>>>>>> /usr/bin/env
>>>>>>> python, some mention /usr/bin/env python3, and none mention python2
>>>>>>> anymore. It
>>>>>>> would be great to have all script use the same shebang, PEP394 [1]
>>>>>>> makes it
>>>>>>> (relatively) clear that in our case, explicitly requiring python3 is
>>>>>>> the way to
>>>>>>> go.
>>>>>>>
>>>>>>> So basically, next step would be to update the documentation, remove
>>>>>>> the Python2
>>>>>>> fallback in root CMakeLists.txt and update shebangs.
>>>>>>>
>>>>>>> Anyone seeing an issue with that approach? I'm still a bit worried
>>>>>>> about
>>>>>>> buildbots still running on py2 (?)
>>>>>>>
>>>>>>> Serge
>>>>>>>
>>>>>>> [0]
>>>>>>> http://lists.llvm.org/pipermail/llvm-dev/2020-January/138730.html
>>>>>>> [1] https://www.python.org/dev/peps/pep-0394/
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> LLVM Developers mailing list
>>>>>>> llvm-dev at lists.llvm.org
>>>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>
>>>>>> _______________________________________________
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>>>>>>
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