线程间通信：使用全局变量

import threading
from time import sleep


s=None #临界资源

def bar():
    print("呼叫foo")
    global s
    s='天王'

def foo():
    print('foo等口令')
    sleep(2)
    print('foo收到%s'%s)

def fun(): #线程bar1被这个fun覆盖掉了，线程之间有同步和互斥
    sleep(1)
    print('内奸出现')
    global s
    s='小鸡'



t1=threading.Thread(name='bar',target=bar)
t2=threading.Thread(name="foo",target=foo)
t3=threading.Thread(name="foo",target=foo)

t1.start()
t2.start()
t3.start()

t1.join()
t2.join()
t3.join()

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线程锁 :

lock=threading.Lock() #创建锁对象

lock.acquire() #上锁

lock.release() #解锁

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