Re: [gentoo-dev] [RFC] Deadlines for next Python implementations

[Patrick McLean <chutzpah@gentoo.org>]

On Mon, 01 Jun 2020 23:04:38 +0200
Michał Górny <mgorny@gentoo.org> wrote:

> On Mon, 2020-06-01 at 13:34 -0700, Patrick McLean wrote:
> > On Mon, 01 Jun 2020 22:27:19 +0200
> > Michał Górny <mgorny@gentoo.org> wrote:
> >   
> > > Hi, everyone.
> > > 
> > > I'd like to be more proactive in avoiding the mess like Python 3.6->3.7
> > > switch were.  For this reason, I think it would be better to set
> > > and publish some early deadlines.  Even if we aren't going to strictly
> > > keep to them, it would help people realize how much time there is left
> > > to finish the preparations.
> > > 
> > > 
> > > Python 3.6→3.7 migration
> > > ========================
> > > We've already switched the profiles but there are still some unmigrated
> > > packages.  We will continue either migrating them or last riting if
> > > migration seems unlikely to happen.  Nevertheless, it is wortwhile to
> > > set some final deadlines.  My proposal is:
> > > 
> > > 
> > > 2020-08-01  Python 3.7 migration deadline
> > > 
> > >    After this date, we lastrite all remaining packages that haven't been
> > >    ported.  This gives people roughly two months, with a ping one month
> > >    from now.
> > > 
> > > 2020-09-15  Python 3.6 target removal
> > > 
> > >    As usual, the interpreter will be kept a bit longer, then moved to
> > >    ::python.  This accounts for some extra time if people decide to
> > >    recover last rited packages last minute.  
> > 
> > Given that 2020-08-15 is still well over a year before the upstream EOL,
> > this might be a little premature. How about we the deprecation dates back
> > by 4 months? We can still have a similar schedule, just a little later. That
> > way we are deprecating 3.6 less than a year before the EOL upstream.
> > 
> > We can keep the 2.7 removal as-is.  
> 
> I don't mind shifting the removal.
> 
> >   
> > > Python 3.7→3.8 migration
> > > ========================
> > > The interpreter is stable but there's still lot of migration work to be
> > > done.  Good news is that because of the delay with 3.7, many packages
> > > are getting 3.7+3.8 or even 3.7+3.8+3.9 simultaneously, so there will be
> > > less work in the future.
> > > 
> > > 
> > > 2020-07-01  Python 3.8 target stable-unmasking goal
> > > 
> > >    This is not really a deadline but I'd like to aim for resolving
> > >    depgraph issues and stabilizing everything needed to unmask python3_7
> > >    target on stable.  Initial set of stablereqs was filed already, 
> > >    and we'll be unmasking the target as soon as the depgraph is clean.
> > > 
> > > 2020-09-01  Python 3.8 migration warning
> > > 
> > >    At this point we tell people it's about time to start actively
> > >    updating their packages.  
> > 
> > Under my suggested timeline, I would say we do this 2020-12-01.  
> 
> ...but I do mind this.  Python 3.8 is something we should very soon,
> and waiting another 6 months to tell people to start testing will just
> make it into another mess like Python 3.7 were.

That's fine with me, I don't mind having a warning about packages not
migrated to 3.8 earlier. I just would to keep 3.6 around for until next
year to give us a little more time to migrate.

> > > 2020-12-01  Python 3.8 migration deadline
> > > 
> > >    We lastrite all the unmigrated packages.  
> > 
> > This could be pushed back to 2020-05-01 to not be too close to the 3.6
> > removal. I personally do not have any strong feelings either way about
> > 3.7, so I would be fine removing 3.6 and 3.7 at the same time if that
> > is easier.  
> 
> I would actually prefer pushing for 3.8 earlier and removing them
> at the same time.  If anything, this would let people who haven't moved
> off 3.6 yet go straight to 3.8 without having them do another update
> in a few months.

That's fine with me. We are actually taking this approach, skipping 3.7
entirely any moving directly to 3.8.

> > > 2021-01-15  Python 3.7 target removal
> > > 
> > >    As above.
> > > 
> > > 
> > > Python 2.7 removal
> > > ==================
> > > I would like to continue removing py2.7 from packages where possible,
> > > and slowly lastriting where clearly impossible.  However,
> > > for the remaining packages I'd like to set a hard deadline.
> > > 
> > > 
> > > 2021-01-01  Final Python 2.7 deadline
> > > 
> > >    That's one year after upstream's EOL.  At this point, we last rite
> > >    all the remaining py2.7 packages.
> > > 
> > > 2021-02-15  Python 2.7 target removal
> > > 
> > >    All packages relying on the target are removed.  The interpreter
> > >    stays for as long as we need it.
> > > 
> > > 
> > > General goal
> > > ============
> > > As a general goal, I'd like to set timelines like this once we decide
> > > that the next interpreter goes stable.  The exact lengths are highly
> > > dependent on properties of the next target.  For example, I suspect
> > > Python 3.9 will be easier for us; so far my testing has shown issues
> > > that are rather easy to solve.
> > >   
> > 
> > Here is an attempt at updating version of ASCII art, from what
> > I can tell, the 'w' at the 3.7->3.8 warning probably belonged
> > in the 3.7 column, I moved it.  
> 
> Thanks.
> 
> >  As I said above, I am personally
> > fine if we make 3.6 and 3.7 removals close together (even at
> > the same time).
> > 
> > Combined timeline
> > =================
> > From the above dates:
> > 
> >             2.7 3.6 3.7 3.8
> > 2020-07-01   |   |   |   u    py3.8 target unmasked
> >              |   |   |   |
> >              |   |   |   |
> >              |   |   |   |
> >              |   |   |   |
> >              |   |   |   |
> >              |   |   |   |
> > 2020-12-01   |   |   w   |    py3.7→3.8 migr. warning
> >              |   |   |   |
> >              |   |   |   |
> > 2021-01-01   m   |   |   |    py2.7 pkg last rites
> >              |   |   |   |
> >              |   |   |   |
> > 2021-02-01   |   m   |   |    py3.6 pkg last rites
> >              |   |   |   |
> > 2021-02-15   x   |   |   |    py2.7 pkg removal
> > 2021-03-15       x   |   |    py3.6 pkg removal
> >                      |   |
> >                      |   |
> >                      |   |
> > 2021-05-01           m   |    py3.7 pkg last rites
> >                      |   |
> >                      |   |
> > 2021-06-15           x   |    py3.7 pkg removal
> >                          |
> >                          v
> > 
> >   
> 
> -- 
> Best regards,
> Michał Górny
>