如何开启守护线程

#多个线程下开守护线程
from threading import Thread
import time
def sayhi():
 print(123)
 time.sleep(1)
 print('end123')
def bar():
 print(456)
 time.sleep(3)
 print('end456')
if __name__ == '__main__':
 t1 = Thread(target=sayhi)
 t2 = Thread(target=bar)
 t1.setDaemon(True) #我是设置守护线程的，必须设置在起动线程之前
 t1.daemon = True #我是设置守护线程的，必须设置在起动线程之前
 t1.start()
 t2.start()
 print('老代吃%s'%'鸟屎是主线程')
#单个线程下开守护线程
from threading import Thread
import time
def task(name):
 time.sleep(2)
 print('%s吃屎'%name)
if __name__ == '__main__':
 t = Thread(target=task, args=('老代', ))
 t.setDaemon(True) #我是设置守护线程的，必须设置在起动线程之前
 t.start()
 print('主 哈哈哈哈')