On 7/6/20 9:04 PM, Matthias Klose wrote: > Starting with Python 3.8, Python upstream changed to a time based yearly > release > schedule, targeting the first release of a major Python version (3.x) for > October of each year. For the transition to 3.8: > > - we add 3.8 as supported in November > - made 3.8 the default in March > - dropped 3.7 in April > > That's a little bit late looking at the Debian release schedule, so a little > speedup would be needed if we want to target the current Python release for > the > current Debian release. For 3.8 Ubuntu started to prepare the switch a bit > earlier, using the results for a better experience in Debian: > > - added 3.8 in mid October > - made 3.8 the default in mid December > > Technically it would be possible to do the defaults change before the Debian > freeze, however there's usually a tail of follow-up upstream releases required > to support a new major Python version, unless you opt for actively backporting > changes in various packages. Having the confidence, that the switch is > feasible > in another distro certainly helps doing the transition in Debian, however it > adds a delay. I don't think it's feasible to do the transition in > experimental > first, or doing a large test rebuild, because it requires keeping the whole > python stack in sync with testing/unstable. > > So what I'm proposing here is to aim to support 3.9 as early as possible as a > supported Python3 version, starting with the 3.9 upstream release, and fixing > stuff on the go. Then decide in November, if we can do the defaults change to > 3.9, or if we drop 3.9 again, or ship with two supported Python3 versions.
This looks reasonable, thanks for opening the discussion and doing the hard work. However, I wouldn't be for shipping 2 supported versions, and would prefer if we could have only one if possible, as otherwise this means running unit tests at build time against 2 python versions, which then takes twice as much build time: that's annoying and useless (because at the end, only one of these versions will be in use). Cheers, Thomas Goirand (zigo)
