锁定指定对象和锁定辅助对象有什么区别？

I was recently asked by a friend of mine who's just starting to play around with threading what the difference between using a secondary object purely for the purpose of locking or just locking the object you're referencing is. I had to admit that I had no idea, can anyone tell me? I will try and demonstrate with a couple of code snippets:I was recently asked by a friend of mine who's