[python-committers] My cavalier and aggressive manner, API change and bugs introduced for basically zero benefit

[Yury Selivanov]

Thanks for this email Victor, it illustrates a lot of pain-points
that some core devs have with CPython development process.

I think that we are lucky that we have you and Serhiy who spend
so much time to push so many improvements to the CPython internals.
I think that while we are working on a new major version of
CPython (3.7 now), it's acceptable to push performance
optimizations without a lengthy discussion on python-dev and a
thorough review by 3+ core developers.  An issue on the bug
tracker explaining the change and showing some benchmarks
should be enough.

Those who want to see the results of Serhiy's and Victor's work
can look at https://speed.python.org/comparison/ and see for
themselves that 3.7 is already faster than 3.6 and 2.7 in most
cases.

To reflect on my own experience: I had a patch to speed up
LOAD_GLOBAL, LOAD_ATTR and LOAD_METHOD early in 3.6 development
cycle.  The patch promised to improve performance 5-20% on some
benchmaks. I sent a few emails to python-dev explaining the
change, explaining the memory usage changes etc.  What I saw is
that only one or two people were interested in the change, and
almost nobody wanted to actually review the change.  I became less
motivated, and in the end I decided to focus on other areas and
postpone my work on that optimization until later.  And later I
regretted that: I should have pushed the change, and we would
have few months to improve and test it, and we would have an
even faster 3.6.  (I'll continue my work on the patch soon).

I think that we need to become less conservative about
development of CPython internals.  At this point it's impossible
to make CPython any faster without invasive refactorings, and
I think it's OK to trust our core developers to make them.

Any public API changes/enhancements should be discussed on
python-dev and thoroughly reviewed though.  API design is
something that a single person usually cannot do well.

Thank you,
Yury