Argument to pool function in multiprocessing module in python

Question

In the python docs for the multiprocessing module the very first example is about the Pool command.

from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    with Pool(5) as p:
        print(p.map(f, [1, 2, 3]))

This script is used to demonstrate how the Pool method can be used to run the same function in parallel for a series of possible arguments.

They do not, however explain or provide the arguments to the Pool method, which in this case equals 5.

What is that argument? Why is it 5 in this case? Does it have something to do with the number of allowed processes at a given time?

Thanks

llllllllll · Accepted Answer · 2018-02-12 13:44:17Z

1

You are not reading the documentation of Pool, you are reading just a simple example.

The real documentation of Pool is here, where the meaning of the number is clearly explained:

processes is the number of worker processes to use. If processes is None then the number returned by os.cpu_count() is used.

answered Feb 12, 2018 at 13:44

llllllllll

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1 Comment

I suspected there had to be more information out there. Thanks