04. CyclicBarrier.md

CyclicBarrier

• when a set of two or more threads must wait at a predetermined point of execution until all threads in the set have reached that point, CyclicBarrier is used.
• it allows you to define a synchronization object that suspends until the specified number of threads has reached the barrier point.

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;

class Task implements Runnable {
    CyclicBarrier cb;

    Task(CyclicBarrier cb){
        this.cb = cb;
    }

    /**
     * Runs this operation.
     */
    @Override
    public void run() {
        String name = Thread.currentThread().getName();
        try {
            System.out.println(name + " reached the barrier point");
            cb.await();
        } catch (InterruptedException | BrokenBarrierException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

public class Main {

    public static void main(String[] args) {
        // calls the lambda on 2 set of 3 threads, since we have 6 threads in the code
        CyclicBarrier cb = new CyclicBarrier(3, ()-> System.out.println("Barrier Reached"));

        new Thread(new Task(cb),"thread1").start();
        new Thread(new Task(cb),"thread2").start();
        new Thread(new Task(cb),"thread3").start();
        new Thread(new Task(cb),"thread4").start();
        new Thread(new Task(cb),"thread5").start();
        new Thread(new Task(cb),"thread6").start();

    }
}