We tried PyPy without much success (and we really tried, six month project just to get it to run our codebase.) Our workload is very heavy on the CPython C API, which makes life difficult for PyPy or any other alternative Python implementation. PyPy is great for a lot of uses, just not a great fit for us.

Have you looked into the new hpy API? https://hpyproject.org/

Sorry to hear that. What were the sticking points?

It was a few years ago and I didn’t work on it directly, so my knowledge is a bit fuzzy, and I think the person who did work on it is no longer at the company. As best I recall the slog to get it working was mostly about C extensions, but I don’t know details. And then once it was working the memory use was worse and it didn’t show perf improvements. This is speculation but I would guess the design of the pypy jit isn’t a great fit for a prefork workload, where the hot paths don’t get hot until postfork, but it’s pretty inefficient to do identical jit compilation in every worker instead of once in the parent process.