> Their argument is that the "sub interpreters" they are adding (each with its own GIL) will fulfil the same use cases of multithreaded code without a GIL, but

> Their argument is that the "sub interpreters" they are adding (each with its own GIL) will fulfil the same use cases of multithreaded code without a GIL, but they still have the overhead of encoding and passing data in the same way you have to with sub processors. This is smart, though, because (even if it's not great) there's a lot of evidence that it works in practice. Specifically, this is almost exactly what JavaScript does with workers. It's not a great API and it's cumbersome to write code for, but it got implemented successfully and people use it successfully (and it didn't slow down the whole web).