代码如下：

import threading, time

class Test1(threading.Thread):

  def __init__(self, name):

    super().__init__(name=name)

  def run(self):

    print('test1 start')

    time.sleep(2)

    print('test1 end')

class Test2(threading.Thread):

  def __init__(self, name):

    super().__init__(name=name)

  # 继承thread必须覆盖的方法

  def run(self):

    print('test2 start')

    time.sleep(4)

    print('test2 end')

if __name__ == '__main__':

  thread1 = Test1('test1')

  thread2 = Test2('test2')

  start_time = time.time()

  thread1.start()

  thread2.start()

  # 使用join方法，这两个线程就会阻塞主线程的运行，print('main')就会后执行

  thread1.join()

  thread2.join()

  print('main')

结果：