java 多线程 CountDownLatch&CyclicBarrier

多线程笔记

• CountDownLatch

用于一个线程或多个线程等待多个线程

 class CountdownLatchExample {

    public static void main(String[] args) throws InterruptedException {
        final int totalThread = 10;
        CountDownLatch countDownLatch = new CountDownLatch(totalThread);
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 0; i < totalThread; i++) {
            executorService.execute(() -> {
                System.out.print("run.." + Thread.currentThread().getId() + "\n");
                countDownLatch.countDown();
            });
        }
        countDownLatch.await();
        System.out.println("end");
        executorService.shutdown();
    }
}

• CyclicBarrier

用于多个线程互相等待，达到一致状态后，这些线程才继续执行

class CyclicBarrierExample {

    public static void main(String[] args) {
        final int totalThread = 10;
        CyclicBarrier cyclicBarrier = new CyclicBarrier(totalThread);
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 0; i < totalThread; i++) {
            executorService.execute(() -> {
                System.out.print("before..");
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException | BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.print("after..");
            });
        }
        executorService.shutdown();
    }
}

• 线程状态

状态
新建	NEW
可运行	RUNABLE
阻塞	BLOCKED
无限期等待	WAITING
限期等待	TIME_WAITING
死亡	TERMINATED