Day 1 covered Java’s Thread class and the intrinsic locks built into every Java object. For a long time this was pretty much all the support that Java provided for concurrent programming. Java 5 changed all that with the introduction of java.util.concurrent. Today we’ll look at the enhanced locking mechanisms it provides.
Intrinsic locks are convenient but limited.
There is no way to interrupt a thread that’s blocked as a result of trying to acquire an intrinsic lock.
There is no way to time out while trying to acquire an intrinsic lock.
There’s exactly one way to acquire an intrinsic lock: a synchronized block.
use shared resources
This means that lock acquisition and release ...