A project that has been floating around in the Python world for a number of
years is now working its way toward inclusion into the language—or not.
“Subinterpreters”, which are separate Python interpreters that can
currently be created via the C API for extensions, are seen by some as a
way to get a more Go-like concurrency model for Python. The first step
toward that goal is to expose that API in the standard library. But there
are questions about whether subinterpreters are actually a desirable
feature for Python at all, as well as whether the hoped-for concurrency
improvements will materialize.

Source: LWN.net – [$] Subinterpreters for Python