多处理：我想更好地理解这段代码

Question

I have found the following lines of code to compute the array mx by the repeated calling of a function called fun .

However, I would like to understand better what it does.

Also, I assigned 16 cores to the parallel pool, however, I noticed that during computations no more than 2 cores are running at the same time.

Could someone explain what this code does and why it could be that only part of the threads is working?

Thank you!

from tqdm import tqdm
from multiprocessing import Pool
from functools import partial

with Pool(processes = 16) as p_mx: 
    mx = tqdm(p_mx.imap(partial(fun, L), nodes), total = n)

Answer 1

multiprocessing.Pool() slower than just using ordinary functions

The function you are trying to parallelize doesn't require enough CPU resources (ie CPU time) to rationalize parallelization!

And may caused by the way Python handle multi-threading and multi-processing with the GIL:

When to use threading and how many threads to use

Look at the GIL , you will have a better understanding of why.

If you want concurrent code in Python 3.8, you have CPU-bound concurrency problems then this could be the ticket!