Day13多进程下载案例问题

from multiprocessing import Process
from os import getpid
from random import randint
from time import time, sleep


def download_task(filename):
    print('启动下载进程，进程号[%d].' % getpid())
    print('开始下载%s...' % filename)
    time_to_download = randint(5, 10)
    sleep(time_to_download)
    print('%s下载完成! 耗费了%d秒' % (filename, time_to_download))


def main():
    start = time()
    p1 = Process(target=download_task, args=('Python从入门到住院.pdf', ))
    p1.start()
    p2 = Process(target=download_task, args=('Peking Hot.avi', ))
    p2.start()
    p1.join()
    p2.join()
    end = time()
    print('总共耗费了%.2f秒.' % (end - start))

if __name__ == '__main__':
     main()

这个案例在Windows 10 1809下的jupyter notebook中永远只打印输出：

总共耗费了0.XX秒.

但是这段代码单独保存为.py文件运行后可以得到正确的结果，请问这是Windows的问题还是Jupyter notebook的问题呢？

Start with the multiprocessing example shown in the issue and compare its behavior in a Windows 10 Jupyter Notebook with the same code run as a .py file. Investigate how the notebook starts child processes and verify whether the child-process output is suppressed or the execution context differs. Done means identifying whether the cause is Windows, Jupyter Notebook, or their interaction and documenting a reproducible explanation.