CountDownLatch.await()挂断

Question

谁能解释为什么 CountDownLatch 方法等待挂起，尽管我在单独的线程中执行 countDown？这个测试永远不会结束，有趣的是 ThreadPoolTaskExecutor 没有在我想执行 countDown 方法的地方执行代码。我确定 ThreadPoolTaskExecutor 在不同的线程中执行回调并且 CountDownLatch::await 将被释放。

import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

...
    private ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

    @Test
    void nestedInitialization() {
        executor.initialize();
        var beanInitializer = new Initializer(executor);
   
        beanInitializer.initialize(() -> {
            new SomeBean().init();
        });

        sleep(150);
        assertEquals(0, executor.getThreadPoolExecutor().getQueue().size());
        assertTrue(beanInitializer.isInitializationDone());
    }

    class SomeBean {
        private AnotherBean anotherBean = new AnotherBean();

        void init() {
            anotherBean.init();
        }
    }

    class AnotherBean {
        private final Initializer initializer = new Initializer(executor);

        void init() {
            initializer.initialize(this::internalInit);
        }

        void internalInit() {
            sleep(100);
        }
    }

    public class Initializer {

        private ThreadPoolTaskExecutor bootstrapExecutor;

        private final CountDownLatch countDownLatch = new CountDownLatch(2);

        private Initializer(ThreadPoolTaskExecutor bootstrapExecutor) {
            this.bootstrapExecutor = bootstrapExecutor;
        }

        public void initialize(Runnable callback) {
            synchronized (this) {
                if (isNotInitialized()) {
                    countDownLatch.countDown(); // set 1 in latch
                    bootstrapExecutor.execute(() -> {
                        callback.run();
                        countDownLatch.countDown(); //  <-- this doesn't execute                   
                  });
                }
            }

            if (initializationStarted()) {
                try { 
                    countDownLatch.await();
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }

        boolean isNotInitialized() { return countDownLatch.getCount() == 2; }

        boolean initializationStarted() { return countDownLatch.getCount() == 1; }

        boolean isInitializationDone() { return countDownLatch.getCount() == 0; }
    }

如果我在 await 方法中设置任何超时，任务执行器中的回调将在超时后执行并测试通过...我无法理解这一点..

Answer 1

问题出在池的大小上。默认情况下 ThreadPoolTaskExecutor 在池中只有一个线程。我增加了 corePolSize，现在他的代码可以工作了。谢谢安德烈亚斯！

CountDownLatch.await()挂断

CountDownLatch.await() hangs up

java

concurrency

spring

countdownlatch

junit5