Day13最后一个例子感觉计时部分不太对啊。。计时前是不是线程就已经开始启动了？

如下，如果我简单改下流程，让start后sleep5秒，实际计算时间就成0.08秒了，这显然不对吧。。

from multiprocessing import Process
from time import time, sleep


def task_handler():
    sleep(5)


def main():
    processes = []
    # 启动8个进程将数据切片后进行运算
    for _ in range(8):
        p = Process(target=task_handler)
        processes.append(p)
        p.start()
    # 开始记录所有进程执行完成花费的时间
    sleep(5)
    start = time()
    for p in processes:
        p.join()
    end = time()
    print('Execution time: ', (end - start), 's', sep='')


if __name__ == '__main__':
    main()

Execution time: 0.08439040184020996s

Start with the Day13 multiprocessing example shown in the issue and inspect where process startup, sleep, timing, and join are ordered. Verify the measured interval against the workers' actual runtime. Done means the lesson explains or corrects the timing measurement so it reflects the intended process execution.