Wait queues

Wait queues hold threads that must wait for a particular event before they can continue to run.

Wait queues coordinate access to shared data by threads. When a user thread tries to acquire the logical-log latch but finds that the latch is held by another user, the thread that was denied access puts itself in the logical-log wait queue. When the thread that owns the lock is ready to release the latch, it checks for waiting threads, and, if threads are waiting, it wakes up the next thread in the wait queue.