Talk about thread sync lock and unlock

Lock can use Condition for scheduling between threads, it has better flexibility, and in an object can have multiple Condition (that is, Object monitor), the thread can be registered in a different Condition, so that can

A selective scheduling thread that is more flexible.

Synchronized uses the object itself notify, wait, notityall scheduling mechanism, equivalent to the entire object only a single condition (that is, the object itself) all the threads are registered on it, thread scheduling

After the time to dispatch all the registered threads, there is no choice, there will be a considerable problem.

The Synchronizer built on Aqs include reentrantlock,Semaphore,countdownlatch, Reetrantread writelock,futuretask , etc.

Talk about thread sync lock and unlock