Python线程。计时器有时会停止、暂停或冻结

我的代码总结如下

import threading
import time

def checkMinute(num):
    print('check ' + str(num))
    print(str(num) + ' work start')
    # other python code....
    print(str(num) + ' work end')
    startTimer(num)

def startTimer(num):
    t = threading.Timer(10, checkMinute, args=(num,))
    t.daemon = True
    t.start()
    
if __name__== '__main__':
    startTimer(1)
    startTimer(2)
    startTimer(3)
    time.sleep(1000)

它必须在键盘插入之前继续工作

但有时，我不知道该怎么说，但它会停止、暂停或冻结

例如，控制台日志如下

# 10am in real time. program is start
2021-04-21 10:00:00 : check 1   
2021-04-21 10:00:00 : 1 work start
2021-04-21 10:00:00 : check 2   
2021-04-21 10:00:00 : 2 work start
2021-04-21 10:00:00 : check 3   
2021-04-21 10:00:00 : 3 work start
2021-04-21 10:00:13 : 1 work end
2021-04-21 10:00:20 : 2 work end
2021-04-21 10:00:21 : 3 work end
# I want continue it
# but sometimes
2021-04-21 17:10:21 : 3 work end
# Next, 'check 1' and '1 work start' have to progress
# But the real time is 9pm, but no progress has been made since the program stopped at 5pm.
# When I input enter on command window, It work again with no error

为什么会这样？ 我怎样才能修好它

python版本是3.6