参考:
http://stackoverflow.com/questions/9072422/difference-between-synchronized-and-reentrantlock-pros-and-cons
多线程之--synchronized 和reentrantlock的优缺点
多线程之--2种JAVA乐观锁的比较( NonfairSync VS. FairSync)
reentrantlock的优点
reentrantlock的缺点
参考:
http://stackoverflow.com/questions/9072422/difference-between-synchronized-and-reentrantlock-pros-and-cons