1. 最普通的锁，单机synchronized锁

2. 锁具体对象

3. mysql锁

4. redis 单线程

5. 分布式锁

参考：

https://www.cnblogs.com/bearbrick0/p/15976399.html

https://www.yuque.com/snailclimb/tangw3/dmi5t01gacg3wa5u

https://xie.infoq.cn/article/ba58e61173f57170a7059ee72