python 多线程复制文件

"""
创建2个进程,
分别复制文件的上半部分和下半部分到一个新的文件中
"""
import os
from multiprocessing import Process
from time import sleep

filename = './images.jpg'

size = os.path.getsize(filename)
fr = open(filename, 'rb')

def top():
    sleep(1)
    # fr = open(filename, 'rb')
    fw = open('top.jpg', 'wb')
    fr.seek(0,0)
    n = size // 2
    fw.write(fr.read(n))
    fr.close()
    fw.close()
    print('top,完成')

def bot():
    # fr = open(filename, 'rb')
    fw = open('bot.jpg', 'wb')
    n = size // 2
    fr.seek(n, 0)
    fw.write(fr.read())
    fr.close()
    fw.close()
    print('bot,完成')


if __name__ == '__main__':
    p1 = Process(target=top)
    p2 = Process(target=bot)
    p1.start()
    p2.start()
    p1.join()
    p2.join()
    print('face', os.path.getsize(filename))
    print('bot', os.path.getsize('bot.jpg'))
    print('top', os.path.getsize('top.jpg'))