Mutex vs Monitor
Explore the differences between mutexes and monitors in Java concurrency. Understand how monitors combine mutual exclusion with condition variables to avoid CPU-wasting spin waiting. This lesson explains how threads interact with monitors, including wait and signal methods, and covers best practices like using while loops for predicate checks in multithreaded applications.
We'll cover the following...
Continuing our discussion from the previous section on locking and signaling mechanisms, we’ll now pore over an advanced concept the monitor. It is exposed as a concurrency construct by some programming language frameworks including Java.
When Mutual Exclusion isn’t Enough
Concisely, a monitor is a mutex and then some. Monitors are generally language level constructs whereas mutex and semaphore are lower-level or OS provided constructs.
To understand monitors, let’s first see the problem they solve. Usually, in multi-threaded applications, a thread needs to wait for some program predicate to be true before it can proceed forward. Think about a producer/consumer application. If the producer hasn’t produced anything the consumer can’t consume anything, so the consumer must wait on a predicate that lets the consumer know that something has indeed ...