I have ported code from Cinder to CPython . The fork has some optimizations that can be easily put in CPython and Facebook is open to port features. I’m not sure if Facebook wants to continually have a fork but CPython is open to have those features merged in if they make sense.
The Cinder team's longterm goal is to upstream as much as we can, and make the rest available as pip-installable extensions that anyone could theoretically install and use on CPython. The fewer internal changes and patches we need to maintain, the faster we can adopt upstream Python releases and all of the associated performance and tooling wins.
