[hot_gril]

Pool executors only solve one kind of use case. They aren't a general solution to concurrency+parallelism.

And they're still the worst version of this pattern, because despite using multiple OS-level threads with all the associated overhead, the GIL prevents most of the real parallelism from happening. And if you want full parallelism, you have to use multiprocessing.Pool, which adds pickling overhead and incompatibility.