Java的客户端的RabbitMQ通过生产者的线程上重新发送挂起提交回调NACK之后，由于不存在交换

我目前正在与故障的情况下通过消息中间件的RabbitMQ通信时可能发生的实验。我们的目标是评估通信怎么这么能做出更有弹性。

我特别希望在发送邮件时触发NACK（未确认）确认生产者提交模式。要做到这一点，我将消息发送到通过Spring AMQP的一个不存在的交换RabbitTemplate.send 。在经由设置回调RabbitTemplate.setConfirmCallback ，我然后处理ack=false通过重新发送该消息到现有的交流（模拟我照顾到NACK原因的）确认。

下面提供了一个示例类和相关测试，完整的示例项目中可以找到我的github仓库。我使用的RabbitMQ 3.6和Spring启动/ AMQP 2.0.2。

运行测试时，回调调用与ack=false预期。然而，重新发送该消息挂起，而重新创建（10分钟后用超时异常）的信道。电话会议的转储的堆栈和下面提供日志。

一个解决问题的办法似乎是在不同的线程发送消息的建议在这里。 如果您取消注释行service.runInSeparateThread = true; 在测试中，工作的事情！

然而，我既不忠实地理解事情为什么（不）工作，我也没有读到这种做法除了上述职位的任何地方。这是预期的行为或错误？有人可以解释的细节？

非常感谢您的咨询！

调用堆栈快照 ：

 "AMQP Connection 127.0.0.1:5672@3968" prio=5 tid=0xe nid=NA waiting
 java.lang.Thread.State: WAITING
  at java.lang.Object.wait(Object.java:-1)
  at com.rabbitmq.utility.BlockingCell.get(BlockingCell.java:73)
  at com.rabbitmq.utility.BlockingCell.uninterruptibleGet(BlockingCell.java:120)
  at com.rabbitmq.utility.BlockingValueOrException.uninterruptibleGetValue(BlockingValueOrException.java:36)
  at com.rabbitmq.client.impl.AMQChannel$BlockingRpcContinuation.getReply(AMQChannel.java:494)
  at com.rabbitmq.client.impl.AMQChannel.privateRpc(AMQChannel.java:288)
  at com.rabbitmq.client.impl.AMQChannel.exnWrappingRpc(AMQChannel.java:138)
  at com.rabbitmq.client.impl.ChannelN.open(ChannelN.java:133)
  at com.rabbitmq.client.impl.ChannelManager.createChannel(ChannelManager.java:176)
  at com.rabbitmq.client.impl.AMQConnection.createChannel(AMQConnection.java:542)
  at org.springframework.amqp.rabbit.connection.SimpleConnection.createChannel(SimpleConnection.java:57)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory$ChannelCachingConnectionProxy.createBareChannel(CachingConnectionFactory.java:1156)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory$ChannelCachingConnectionProxy.access$200(CachingConnectionFactory.java:1144)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.doCreateBareChannel(CachingConnectionFactory.java:585)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.createBareChannel(CachingConnectionFactory.java:568)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.getCachedChannelProxy(CachingConnectionFactory.java:538)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.getChannel(CachingConnectionFactory.java:520)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.access$1500(CachingConnectionFactory.java:94)
  at org.springframework.amqp.rabbit.connection.CachingConnectionFactory$ChannelCachingConnectionProxy.createChannel(CachingConnectionFactory.java:1161)
  at org.springframework.amqp.rabbit.core.RabbitTemplate.doExecute(RabbitTemplate.java:1803)
  at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:1771)
  at org.springframework.amqp.rabbit.core.RabbitTemplate.send(RabbitTemplate.java:859)
  ...

日志：

...
10:21:24.613 [main] DEBUG org.springframework.amqp.rabbit.core.RabbitAdmin - declaring Exchange 'ExistentExchange'
10:21:24.630 [main] INFO com.example.rabbitmq.ProducerService - sending `initial Message`
10:21:24.648 [main] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - Added listener org.springframework.amqp.rabbit.core.RabbitTemplate$MockitoMock$952329793@562c877a
10:21:24.648 [main] DEBUG org.springframework.amqp.rabbit.core.RabbitTemplate - Added publisher confirm channel: Cached Rabbit Channel: PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1), conn: Proxy@3013909b Shared Rabbit Connection: SimpleConnection@12db3386 [delegate=amqp://guest@127.0.0.1:5672/, localPort= 1341] to map, size now 1
10:21:24.649 [main] DEBUG org.springframework.amqp.rabbit.core.RabbitTemplate - Executing callback RabbitTemplate$$Lambda$175/1694519286 on RabbitMQ Channel: Cached Rabbit Channel: PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1), conn: Proxy@3013909b Shared Rabbit Connection: SimpleConnection@12db3386 [delegate=amqp://guest@127.0.0.1:5672/, localPort= 1341]
10:21:24.649 [main] DEBUG org.springframework.amqp.rabbit.core.RabbitTemplate - Publishing message (Body:'[B@67001148(byte[15])' MessageProperties [headers={}, contentType=application/octet-stream, contentLength=0, deliveryMode=PERSISTENT, priority=0, deliveryTag=0])on exchange [nonExistentExchange], routingKey = [nonExistentQueue]
10:21:24.659 [main] INFO com.example.rabbitmq.ProducerService - done with sending message
10:21:24.675 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1) PC:Nack:(close):1
10:21:24.677 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - Sending confirm PendingConfirm [correlationData=null cause=channel error; protocol method: #method<channel.close>(reply-code=404, reply-text=NOT_FOUND - no exchange 'nonExistentExchange' in vhost '/', class-id=60, method-id=40)]
10:21:24.677 [AMQP Connection 127.0.0.1:5672] INFO com.example.rabbitmq.ProducerService - In confirm callback, ack=false, cause=channel error; protocol method: #method<channel.close>(reply-code=404, reply-text=NOT_FOUND - no exchange 'nonExistentExchange' in vhost '/', class-id=60, method-id=40), correlationData=null
10:21:24.677 [AMQP Connection 127.0.0.1:5672] INFO com.example.rabbitmq.ProducerService - sending `resend Message`
10:21:24.678 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1) PC:Nack:(close):1
10:21:24.679 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - AMQChannel(amqp://guest@127.0.0.1:5672/,1) No listener for seq:1
10:21:24.679 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.core.RabbitTemplate - Removed publisher confirm channel: PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1) from map, size now 0
10:21:24.679 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.core.RabbitTemplate - Removed publisher confirm channel: PublisherCallbackChannelImpl: AMQChannel(amqp://guest@127.0.0.1:5672/,1) from map, size now 0
10:21:24.679 [AMQP Connection 127.0.0.1:5672] DEBUG org.springframework.amqp.rabbit.support.PublisherCallbackChannelImpl - PendingConfirms cleared

ProducerService：

@Service
public class ProducerService {

    static final String EXISTENT_EXCHANGE = "ExistentExchange";
    private static final String NON_EXISTENT_EXCHANGE = "nonExistentExchange";
    private static final String QUEUE_NAME = "nonExistentQueue";
    private final Logger logger = LoggerFactory.getLogger(getClass());
    private final RabbitTemplate rabbitTemplate;
    private final Executor executor = Executors.newCachedThreadPool();
    boolean runInSeparateThread = false;

    public ProducerService(RabbitTemplate rabbitTemplate) {
        this.rabbitTemplate = rabbitTemplate;
        rabbitTemplate.setConfirmCallback(this::confirmCallback);
    }

    private void confirmCallback(CorrelationData correlationData, boolean ack, String cause) {
        logger.info("In confirm callback, ack={}, cause={}, correlationData={}", ack, cause, correlationData);
        if (!ack) {
            if (runInSeparateThread) {
                executor.execute(() -> sendMessage("resend Message", EXISTENT_EXCHANGE));
            } else {
                sendMessage("resend Message", EXISTENT_EXCHANGE);
            }
        } else {
            logger.info("sending was acknowledged");
        }
    }

    public void produceMessage() {
        sendMessage("initial Message", NON_EXISTENT_EXCHANGE);
    }

    private void sendMessage(String messageBody, String exchangeName) {
        logger.info("sending `{}`", messageBody);
        rabbitTemplate.send(exchangeName, QUEUE_NAME, new Message(messageBody.getBytes(), new MessageProperties()));
        logger.info("done with sending message");
    }

}

ProducerServiceTest：

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = {RabbitAutoConfiguration.class, ProducerService.class})
@DirtiesContext
public class ProducerServiceTest {

    @Autowired
    private ProducerService service;
    @SpyBean
    private RabbitTemplate rabbitTemplate;
    @Autowired
    private AmqpAdmin amqpAdmin;
    @Autowired
    private CachingConnectionFactory cachingConnectionFactory;

    @Before
    public void setup() {
        cachingConnectionFactory.setPublisherConfirms(true);
        amqpAdmin.declareExchange(new DirectExchange(ProducerService.EXISTENT_EXCHANGE));
    }

    @After
    public void cleanup() {
        amqpAdmin.deleteExchange(ProducerService.EXISTENT_EXCHANGE);
    }

    @Test
    public void sendMessageToNonexistentExchange() throws InterruptedException {
        final CountDownLatch sentMessagesLatch = new CountDownLatch(2);
        final List<Message> sentMessages = new ArrayList<>();
        doAnswer(invocation -> {
            invocation.callRealMethod();
            sentMessages.add(invocation.getArgument(2));
            sentMessagesLatch.countDown();
            return null;
        }).when(rabbitTemplate).send(anyString(), anyString(), any(Message.class));

//        service.runInSeparateThread = true;
        service.produceMessage();
        sentMessagesLatch.await();

        List<String> messageBodies = sentMessages.stream().map(message -> new String(message.getBody())).collect(toList());
        assertThat(messageBodies, equalTo(Arrays.asList("initial Message", "resend Message")));
    }

}

它可以被认为是一个错误，我想，但它是我们缓存渠道来提高性能的方法的人工制品。问题是，试图多数民众赞成提供一个ACK针对同一信道在同一线程上的频道上发布引起客户端库僵局。

我们有一个悬而未决的问题寻找到一个解决方案（出于不同的原因）; 我们只是还没有得到解决它。据我所知，你是唯一的第二个用户打这6年多以来，我们增加了确认和回报支持。

编辑

其实，这是一种不同的情况; 由于通道关闭它不重用的通道。它试图创建一个新的渠道，这是什么陷入僵局。我不认为我们（春季AMQP）怎么可以做任何事情; 它的Java客户端的限制; 你不能在ACK线程上执行操作。