CyclicBarrier使用

CyclicBarrier顧名思義循環栅欄，可以了解為障礙點，需要定義的所有線程都到達障礙點之後，線程才能繼續往下執行。

與CountDownLatch不同的是，一組線程都需要阻塞等待，直到所有線程達到障礙點。CountDownLatch是一個線程等待，直到其他線程發來消息

多個線程間共用一個CyclicBarrier對象，每個線程調用await（）方法到達栅欄處

示例

public class UseCyclicBarrier {

	static class Runner implements Runnable {  
	    private CyclicBarrier barrier;  
	    private String name;  
	    
	    public Runner(CyclicBarrier barrier, String name) {  
	        this.barrier = barrier;  
	        this.name = name;  
	    }  
	    @Override  
	    public void run() {  
	        try {  
	            Thread.sleep(1000 * (new Random()).nextInt(5));  
	            System.out.println(name + " 準備OK.");  
	            barrier.await();  
	        } catch (InterruptedException e) {  
	            e.printStackTrace();  
	        } catch (BrokenBarrierException e) {  
	            e.printStackTrace();  
	        }  
	        System.out.println(name + " Go!!");  
	    }  
	} 
	
    public static void main(String[] args) throws IOException, InterruptedException {  
        CyclicBarrier barrier = new CyclicBarrier(3);  // 3 
        ExecutorService executor = Executors.newFixedThreadPool(3);  
        
        executor.submit(new Thread(new Runner(barrier, "zhangsan")));  
        executor.submit(new Thread(new Runner(barrier, "lisi")));  
        executor.submit(new Thread(new Runner(barrier, "wangwu")));  
  
        executor.shutdown();  
    }  
  
}