A DESCRIPTION OF THE PROBLEM :
The writer thread may not wake up in concurrent read/write situations.

Step 1: A reader thread first changes the lockState from 0 to 4.

Step 2: Another writer thread fails to acquire the lock, set the waiter property to the current writer thread and prepare to suspend itself.

Step 3: The reader releases the lock and wakes up the writer.

Step 4: The writer suspends itself by calling LockSuppot.park(this).
The writer thread can no longer be woken up.


FREQUENCY : rarely