python多线程————8、多线程与多进程对比

#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，进程切换代价要高于线程
import time
from concurrent.futures import ThreadPoolExecutor,ProcessPoolExecutor,as_completed

#1、对于耗费cpu的操作，多进程优于多线程
def fib(n):
    if n<=2:
        return 1
    else:
        return fib(n-1) + fib(n-2)

# if __name__ == "__main__":
#     start_time = time.time()
#     with ThreadPoolExecutor(5) as executor:
#     #ProcessPoolExecutor
#         all_task = [executor.submit(fib,(x)) for x in range(30,45)]
#         for future in as_completed(all_task):
#             data = future.result()
#             print(data)
#         print(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__":
    start_time = time.time()
    with ThreadPoolExecutor(5) as executor:
     #ProcessPoolExecutor
        all_task = [executor.submit(random_sleep,(x)) for x in [2]*20]
        for future in as_completed(all_task):
            data = future.result()
            print(data)
        print(time.time()-start_time)