Java并发中CountDownLatch和CyclicBarrier之间的区别

CountDownLatch和CyclicBarrier都在多线程环境中使用，它们都是其中的一部分。

根据Java Doc-

CountDownLatch-同步辅助，允许一个或多个线程等待，直到在其他线程中执行的一组操作完成。

CyclicBarrier-同步帮助，允许一组线程互相等待以到达一个公共的障碍点。

CyclicBarrier的示例

public class Main {
   public static void main(String args[]) throws InterruptedException {
      ExecutorService executors = Executors.newFixedThreadPool(4);
      CyclicBarrier cyclicBarrier = new CyclicBarrier(5);
      executors.submit(new Service1(cyclicBarrier));
      executors.submit(new Service1(cyclicBarrier));
      executors.submit(new Service2(cyclicBarrier));
      executors.submit(new Service2(cyclicBarrier));
      executors.submit(new Service2(cyclicBarrier));
      Thread.sleep(3000);
      System.out.println("Done");
   }
}
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
public class Service1 implements Runnable {
   CyclicBarrier cyclicBarrier;
   public Service1(CyclicBarrier cyclicBarrier) {
      super();
      this.cyclicBarrier = cyclicBarrier;
   }
   @Override
   public void run() {
      System.out.println("Services1" + cyclicBarrier.getNumberWaiting());
      while (true) {
         try {
            cyclicBarrier.await();
         } catch (InterruptedException | BrokenBarrierException e) {
            //TODO自动生成的捕获块
            e.printStackTrace();
         }
      }
   }
}
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
public class Service2 implements Runnable {
   CyclicBarrier cyclicBarrier;
   public Service2(CyclicBarrier cyclicBarrier) {
      super();
      this.cyclicBarrier = cyclicBarrier;
   }
   @Override
   public void run() {
      System.out.println("Services2" + cyclicBarrier.getNumberWaiting());
      while (true) {
         try {
            cyclicBarrier.await();
         } catch (InterruptedException | BrokenBarrierException e) {
            //TODO自动生成的捕获块
            e.printStackTrace();
         }
      }
   }
}

CountDownLatch的示例

public class Main {
   public static void main(String args[]) throws InterruptedException {
      ExecutorService executors = Executors.newFixedThreadPool(4);
      CountDownLatch latch= new CountDownLatch(2);
      executors.submit(new Service1(latch));
      executors.submit(new Service2(latch));
      latch.await();
      System.out.println("Done");
   }
}
import java.util.concurrent.CountDownLatch;

public class Service1 implements Runnable {

   CountDownLatch latch;
   public Service1(CountDownLatch latch) {
      super();
      this.latch = latch;
   }

   @Override
   public void run() {
      try {
         Thread.sleep(20000);
      } catch (InterruptedException e) {
         //TODO自动生成的捕获块
         e.printStackTrace();
      }
      latch.countDown();
      System.out.println("Services2"+latch.getCount());
   }
}
import java.util.concurrent.CountDownLatch;
public class Service2 implements Runnable {
   CountDownLatch latch;
   public Service2(CountDownLatch latch) {
      super();
      this.latch = latch;
   }
   @Override
   public void run() {
      try {
         Thread.sleep(20000);
      } catch (InterruptedException e) {
         //TODO自动生成的捕获块
         e.printStackTrace();
      }
      latch.countDown();
      System.out.println("Services2"+latch.getCount());
   }
}