[5.1 乐观锁、悲观锁和自旋锁](5.1%E4%B9%90%E8%A7%82%E9%94%81%E3%80%81%E6%82%B2%E8%A7%82%E9%94%81%E5%92%8C%E8%87%AA%E6%97%8B%E9%94%81.md) [5.2 Synchronized](5.2Synchronized.md) [5.3 ReentrantLock](5.3ReentrantLock.md) [5.4 公平锁和非公平锁](5.4%E5%85%AC%E5%B9%B3%E9%94%81%E5%92%8C%E9%9D%9E%E5%85%AC%E5%B9%B3%E9%94%81.md) [5.3.1 说说ReentrantLock的实现原理，以及ReentrantLock的核心源码是如何实现的？](5.3.1%E8%AF%B4%E8%AF%B4ReentrantLock%E7%9A%84%E5%AE%9E%E7%8E%B0%E5%8E%9F%E7%90%86%EF%BC%8C%E4%BB%A5%E5%8F%8AReentrantLock%E7%9A%84%E6%A0%B8%E5%BF%83%E6%BA%90%E7%A0%81%E6%98%AF%E5%A6%82%E4%BD%95%E5%AE%9E%E7%8E%B0%E7%9A%84%EF%BC%9F.md) [5.5 锁优化和升级](5.5%E9%94%81%E4%BC%98%E5%8C%96%E5%92%8C%E5%8D%87%E7%BA%A7.md)