Java CountDownLatch is a class in Java's java.util.concurrent package that allows one or more threads to wait for a set of operations to complete before proceeding. It provides a mechanism for synchronizing threads based on a countdown, where threads wait until the countdown reaches zero. Introduced in Java 2004 with Java 5, CountDownLatch is useful for managing thread coordination, especially in parallel processing or multi-step tasks.

https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CountDownLatch.html