多线程和多进程对比

from concurrent.futures import ThreadPoolExecutor,as_completed
import time
from concurrent.futures import ProcessPoolExecutor


#多进程编程
#耗CPU的操作，用多进程编程，对于IO操作来说，使用多线程编程，进程切换代价高于线程。

#1 对于耗CPU的操作，多进程由于多线程

def fib(n):
    if n<=2:
        return 1
    return fib(n-1)+fib(n-2)

"""
if __name__ == "__main__":#使用多进程一定要加"if __name__ == "__main__"
    # 利用多进程测试程序运行的时间 ：last time is: 5.340000152587891
    with ProcessPoolExecutor(3) as executor:
        all_task = [executor.submit(fib, (num)) for num in range(20, 35)]
        start_time = time.time()
        for future in as_completed(all_task):
            data = future.result()
            print('exe result  {}'.format(data))

        print('last time is: {}'.format(time.time() - start_time))



if __name__ == "__main__":
    #利用多线程测试程序运行的时间 ：last time is: 6.2900002002716064
    with ThreadPoolExecutor(max_workers=3) as executor:
        all_task=[executor.submit(fib,(num)) for num in range(20, 35)]
        start_time=time.time()
        for future in as_completed(all_task):
            data=future.result()
            print('exe result  {}'.format(data))
    
        print('last time is: {}'.format(time.time()-start_time))
"""

#2 对于IO操作来说，多线程优于多进程


def random_sleep(n):
    time.sleep(n)
    return n

"""
if __name__ == "__main__":
    # 利用多线程测试程序运行的时间 ：20.001999855041504
    with ThreadPoolExecutor(max_workers=3) as executor:
        all_task = [executor.submit(random_sleep, (num)) for num in [2]*30]#20个2的列表
        start_time = time.time()
        for future in as_completed(all_task):
            data = future.result()
            print('exe result  {}'.format(data))

        print('last time is: {}'.format(time.time() - start_time))


"""

if __name__ == "__main__":
    # 利用多进程测试程序运行的时间 ：20.47699999809265
    with ProcessPoolExecutor(max_workers=3) as executor:
        all_task = [executor.submit(random_sleep, (num)) for num in [2]*30]#20个2的列表
        start_time = time.time()
        for future in as_completed(all_task):
            data = future.result()
            print('exe result  {}'.format(data))

        print('last time is: {}'.format(time.time() - start_time))