利用@Async实现多线程，如果进行阻塞等待所有结果处理完毕？使用countDownLatch.await()为何无效？

Question

    @Test
    public void TestAsync() throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(10);
        for (int i=0;i<10;i++){
            try {
                testService.asyncTest(i);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                countDownLatch.countDown();
            }
        }
        try {
            countDownLatch.await();
        } catch (Exception e) {
            System.out.println("阻塞异常");
        }
        System.out.println("执行了");
    }

    @Async
    public void asyncTest(int i) throws InterruptedException {
        System.out.println("线程" + Thread.currentThread().getName() + " 执行异步任务：" + i);
        //模拟任务执行时间：500ms
        Thread.sleep(500);
    }

@Configuration
@EnableAsync
public class AsyncConfig {
    @Bean
    public TaskExecutor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        // 设置核心线程数
        executor.setCorePoolSize(3);
        executor.setMaxPoolSize(5);
        executor.setQueueCapacity(10);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("test-async-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.setWaitForTasksToCompleteOnShutdown(true);
        return executor;
    }
}

由于设置了核心线程数为3，所以就只执行了前3个线程，就结束了...，如果做到让他把所有线程都执行完毕再结束？从网上查到资料说用countDownLatch.await()来阻塞，等待所有线程执行完毕，然而使用后无效，求解~

Answer 1

    @Async
    public void asyncTest(int i) throws InterruptedException {
        System.out.println("线程" + Thread.currentThread().getName() + " 执行异步任务：" + i);
        //模拟任务执行时间：500ms
        Thread.sleep(500);
        countDownLatch.countDown();

    }

countDownLatch.countDown(); 不放在Test里，放在执行任务代码里试下。
另外按理来说你这个代码应该是打印十次才对，跟核心线程数应该是没关系的吧

Answer 2

@Async

表示这个方法会以一个新的线程来运行。 countDownLatch是用来控制当前线程的，当前线程和新的线程当然没有关联。

Answer 3

你这应该只有主线程减去1，countDownLatch.countDown()应该放到子线程里面