栅栏(java并发编程实战5.5.4)

迈不过友情╰ 2022-07-12 04:28 146阅读 0赞

栅栏类似于闭锁，它能阻塞一组线程直到某个事件发生。栅栏与闭锁的关键区别在于，所有线程必须同时到达栅栏位置，

才能继续执行。闭锁用于等待事件，而栅栏用于等待其他线程，且能够重复执行。

import java.util.concurrent.BrokenBarrierException;
    import java.util.concurrent.CyclicBarrier;
    
    public class TestCyclicBarrier {
    	
    	private final CyclicBarrier barrier;
    	private final Worker[] workers;
    	
    	public TestCyclicBarrier() {
    		int count = Runtime.getRuntime().availableProcessors();
    		barrier = new CyclicBarrier(count, new Runnable() {
    			@Override
    			public void run() {
    				System.out.println("所有线程均到达栅栏位置，开始下一轮");
    			}
    		});
    		this.workers = new Worker[count];
    		for(int i = 0; i < count; i++) {
    			workers[i] = new Worker(i);
    		}
    	}
    
    	private class Worker implements Runnable {
    		int i;
    		
    		public Worker(int i) {
    			this.i = i;
    		}
    
    		@Override
    		public void run() {
    			for(int index = 1; index < 3; index++) {
    				System.out.println("线程" + i + "第" + index + "次到达栅栏位置，等待其他线程!");
    				try {
    					barrier.await();
    				} catch (InterruptedException e) {
    					e.printStackTrace();
    				} catch (BrokenBarrierException e) {
    					e.printStackTrace();
    				}
    			}
    		}
    		
    	}
    	
    	public void start() {
    		for(int i = 0; i < workers.length; i++) {
    			new Thread(workers[i]).start();
    		}
    	}
    	
    	public static void main(String[] args) {
    		new TestCyclicBarrier().start();
    	}
    	
    }