5.AQS

1. What it is. A queue synchronizer used to implement other concurrency utilities in JUC. 2. How to use it. 3. Principle analysis: queue structure, lock acquisition, enqueueing, parking, cancellation, interruption recovery, and lock release.

Build a simple AQS-like lock by hand to better understand the real AQS source code: requirements, fields, blocking/waking, waiter queue, lock/unlock flow, fairness, final implementation, test, and flow.