Java Thread How to - Create deadlock with CountDownLatch

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Question

We would like to know how to create deadlock with CountDownLatch.

Answer

//from   www .  j a  v a 2 s.  c  o m
import java.util.concurrent.CountDownLatch;

public class Main {

  public static void main(String[] args) {
    Object obj1 = new Object();
    Object obj2 = new Object();
    CountDownLatch latch = new CountDownLatch(2);

    new Locker(obj1, obj2, latch).start();
    new Locker(obj2, obj1, latch).start();
  }
}

class Locker extends Thread {
  CountDownLatch latch;
  Object obj1;
  Object obj2;

  Locker(Object obj1, Object obj2, CountDownLatch latch) {
    this.obj1 = obj1;
    this.obj2 = obj2;
    this.latch = latch;
  }

  @Override
  public void run() {
    synchronized (obj1) {
      latch.countDown();
      try {
        latch.await();
      } catch (Exception e) {
        e.printStackTrace();
      }
      synchronized (obj2) {
        System.out.println("Thread finished");
      }
    }
  }
}

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