Process pool and thread pool

Why use 'pool':

    The pool is used to limit the number of concurrent tasks, and limit our computer to perform tasks concurrently within a range that we can afford.

When to install processes in the pool: Concurrent tasks are computationally intensive.

When to install threads in the pool: Concurrent tasks are I/O intensive.

Use of the process pool

from concurrent.futures import ProcessPoolExecuto

import time,os,random


def task(x):
    print('%s goes to service' %os.getpid())
    time.sleep (random.randint (4,5))
    return x**2

if __name__ == '__main__':
    p=ProcessPoolExecutor(max_workers=5)#The number of processes opened by default is the number of cpu cores

    for i in range(20):
        p.submit(task,i)

operation result:

Use of thread pool:

from concurrent.futures import ThreadPoolExecutor

import time,os,random


def task(x):
    print('%s goes to service' %os.getpid())
    time.sleep (random.randint (4,5))
    return x**2

if __name__ == '__main__':
    p=ThreadPoolExecutor()#The number of processes opened by default is the number of cpu cores

    for i in range(20):
        p.submit(task,i)

operation result: