import threading
from time import sleep,ctime
def sing():
  for i in range(3):
    print("正在唱歌...%d"%i)
    sleep(1)
def dance():
  for i in range(3):
    print("正在跳舞...%d"%i)
    sleep(1)
if __name__ == '__main__':
  print('---开始---:%s'%ctime())
  t1 = threading.Thread(target=sing)
  t2 = threading.Thread(target=dance)
  t1.start()
  t2.start()
  #sleep(5) # 屏蔽此行代码，试试看，程序是否会立马结束？
  print('---结束---:%s'%ctime())
"""
输出结果：
---开始---:Sat Aug 24 08:44:21 2019
正在唱歌...0
正在跳舞...0---结束---:Sat Aug 24 08:44:21 2019
正在唱歌...1
正在跳舞...1
正在唱歌...2
正在跳舞...2
"""

import threading
import time

class MyThread(threading.Thread):
  def run(self):
    for i in range(3):
      time.sleep(1)
      msg = "I'm "+self.name+' @ '+str(i) #name属性中保存的是当前线程的名字
      print(msg)
if __name__ == '__main__':
  t = MyThread()
  t.start()
"""
输出结果：
I'm Thread-5 @ 0
I'm Thread-5 @ 1
I'm Thread-5 @ 2
"""

from concurrent.futures import ThreadPoolExecutor
import time
import os
def sayhello(a):
  for i in range(10):
    time.sleep(1)
    print("hello: " + a)
def main():
  seed = ["a", "b", "c"]
  # 最大线程数为3，使用with可以自动关闭线程池，简化操作
  with ThreadPoolExecutor(3) as executor:
    for each in seed: 
      # map可以保证输出的顺序, submit输出的顺序是乱的
      executor.submit(sayhello, each)
  print("主线程结束")
if __name__ == '__main__':
  main()