[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)