import threading
def sing():
print('进入sing -----------------')
for i in range(3):
print('进入sing循环 -----------------')
l1.acquire()
print('sing上锁 -----------------')
print('唱歌。。。')
try:
print('dance解锁 -----------------')
l2.release()
print('dance解锁成功 -----------------')
except Exception:
print('sing中dance解锁失败，重新开始循环----------------')
pass
def dance():
print('进入dance -----------------')
for i in range(3):
print('进入dance循环 -----------------')
l2.acquire()
print('dance上锁 -----------------')
print('跳舞。。。')
try:
print('sing解锁 -----------------')
l1.release()
print('sing解锁成功 -----------------')
except Exception:
print('dance中sing解锁失败，重新开始循环----------------')
pass
if __name__ == '__main__':
# sing()
# dance()
l1 = threading.Lock()
print(l1)
l2 = threading.Lock()
print(l2)
t1 = threading.Thread(target=sing)
t2 = threading.Thread(target=dance)
print('线程创建完毕--------')
t1.start()
print('线程1开始执行------')
t2.start()
print('线程2开始执行------')
t1.join()
print('线程1守护主线程-----')
t2.join()
print('线程2守护主线程-----')
这里我们暂且先不提全局解释器锁，从这个代码例子里我们可以看出，一个锁在上锁以后，如果在没有释放它的情况下再要对它上锁，他就会阻塞住，一直到它的锁被释放了以后才能够再次被上锁，这样就实现了两个线程的交替执行。
