[hn8726]

> not the best choice for cpu-bound work, which is likely what you're running into with pandas

I'm not a Python user, why is it not good for cpu-bound work? I see the defaults assume some I/O work, but with `max_workers=~cpu_count` it should be what typical dispatchers for CPU-bound work do in other languages

[dkh]

Python "threads" aren't real threads in the traditional sense because Python's Global Interpreter Lock (GIL) exists, and this means no more than one thread is ever actually running in parallel. They are great for network IO since most IO is just spent waiting for stuff rather than computing anything, but you can't actually run CPU-heavy stuff on multiple Python threads and have the speed multiplier be equal to the number of thread workers. For this, you have to use process pools. (Though this is something that is in the process of finally being alleviated/fixed!)

[lyu07282]

This seems all a bit misleading to beginners, if you have numerical cpu-bound work in Python what you should be doing is vectorize it, not parallelize.

https://www.geeksforgeeks.org/vectorized-operations-in-numpy...

[dkh]

The point is that the use-case here is one where there is far more IO-bound work than CPU-bound.