最近在开发计算量较大的模块中使用到的线程协作总结
需求
要求三个线程按下图所示的流程协同执行
实现
public class ThreadDemo {
public static void main(String[] args) {
final CountDownLatch countDownLatch = new CountDownLatch(2);
final CyclicBarrier cyclicBarrier = new CyclicBarrier(2);
Thread threadA = new Thread(new worker("A", countDownLatch, cyclicBarrier));
Thread threadB = new Thread(new worker("B", countDownLatch, cyclicBarrier));
threadB.start();
threadA.start();
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("All worke done");
}
public static void threadSleep() {
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class worker implements Runnable {
private String workerNmae;
private CountDownLatch countDownLatch;
private CyclicBarrier cyclicBarrier;
public worker(String workerNmae, CountDownLatch countDownLatch, CyclicBarrier cyclicBarrier) {
this.workerNmae = workerNmae;
this.countDownLatch = countDownLatch;
this.cyclicBarrier = cyclicBarrier;
}
public void run() {
System.out.println(this.workerNmae + " start work");
ThreadDemo.threadSleep();
try {
this.cyclicBarrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
ThreadDemo.threadSleep();
System.out.println(this.workerNmae + " end work");
countDownLatch.countDown();
}
}区别
不难看出，这两个对象使用的时机、方式有所不同，CyclicBarrier的await使工作线程阻塞；CountDownLatch的await在需要并行节点结束时使用，达到线程协作。