# Problem 5.4: Work queue of limited length using semaphores

Implement the work queue of limited length from problem 4.2 using semaphores as the only
synchronization mechanism, i.e. without `synchronized` blocks or methods (and, consequentially,
not `wait()` or `notify()`). Test your program with your own semaphore class from problem 5.3 and
with `java.util.concurrent.Semaphore`. Make sure not to use busy waiting: If a thread has
to wait, use semaphore operations for this.