Do you know that contended AtomicLong.increment() works in JDK 8 much faster than in JDK 7? There are a lot of ways to implement thread-safe counters in Java and 100500 ways to shoot yourself in the foot when you doing this.

During this talk we will consider several ways of implementing thread-safe counters (synchronized, Lock, AtomicLong, Unsafe), compare their performance, and try to understand why some implementations are faster than others in this or that scenario.