What is real purpose of this wait-notify thread semantics?

Question

I just came across some code which uses wait-notify construct to communicate with thread defined in a class, by its other member-methods. Amusingly, after acquiring lock, all t

Answer 1

As described here,

The wait-notify pattern is used in a broad set of cases where one thread needs to tell other threads that some event has occurred. It is commonly used to implement a thread pool or producer-consumer scenario, where a particular thread or threads need to "pick up jobs" created by other threads (in this case, the "event" that has occurred is that a job has arrived for one of the threads to pick up).

Answer 2

after acquiring lock, all thread does in synchronized scope is timed-wait on same lock (see below snippet).

Yes, the pattern is strange. Typically I have a loop similar to that (although I always use a private final lockObject) that waits for a small amount of time because I don't want the method to spin -- performing its task too often.

I would have thought that the other method would lock on the same variable and then update the isShuttingDown flag. But doing the other // useful# sections is a strange pattern since there are a number of race conditions with the code that is going to make determining the order of the useful sections impossible.