CyclicBarrier

A CyclicBarrier is a synchronization tool that lets a fixed number of threads wait for each other at a shared meeting point. When the last thread arrives, the barrier "trips", and all waiting threads proceed together. The previous lesson on CountDownLatch covered a one-shot finish-gate where some threads wait for others to be done. This lesson covers the opposite shape: a reusable rendezvous where every participant waits for every other participant before anyone moves on. It covers the API, the trip mechanics, the optional barrierAction, broken barriers, reset(), and the differences from CountDownLatch. The running examples are a multi-stage daily-report job and a batched load-test scenario.

CyclicBarrier lives in java.util.concurrent. It has been in the JDK since Java 5, alongside the rest of the java.util.concurrent family.