Thread.sleep() 是否释放ReentrantLock？

       The Thread.sleep() method effectively "pauses" the current thread for a given period of time. We used it in our very firstthreading example to make threads display a message periodically, sleeping between messages. From the outset, it's important to be aware of the following:

• it is always the current thread that is put to sleep;
• the thread might not sleep for the required time (or even at all);
• the sleep duration will be subject to some system-specific granularity, typically 1ms;
• while sleeping, the thread still owns synchronization locks it has acquired;
• the sleep can be interrupted (sometimes useful for implementing a cancellation function);
• calling sleep() with certain values can have some subtle, global effects on the OS (see below), and vice versa, other threads and processes running on the system can have subtle effects on the observed sleep duration.

当我在线程中使用ReentrantLock而非关键字synchronized时发现，此时sleep似乎释放了ReentrantLock。

Why？ What difference between ReentrantLock and synchronized when thread sleeps?