记一次 RabbitMQ 消费者莫名消失问题的排查-牛翰网

记一次 RabbitMQ 消费者莫名消失问题的排查

开心一刻

今天好哥们找我借钱
哥们:兄弟,我最近手头紧,能不能借我点…
我:我手头也不宽裕,要不你试试银行贷款或者花呗?
哥们:不行,那个借了要还的
我:…

问题回顾

某天下午,生产监控告警:消息积压,队列 xxx 消息数超过 100;我第一时间想到的是应用服务是不是停了,但应用服务存活监控又没有告警,但我还是找值班运维同事帮忙确认了下,确认结果是服务的 6 个节点都是存活的,然后我又让运维确认了下队列的消费者情况,结果发现消费者列表中只有 2 个节点的消费者,其他 4 个节点的消费者不见了,所以消息消费不过来,导致了消息积压!

所以问题来了

那 4 个节点的注册的消费者为何消失?

但当务之急是解决消息积压的问题,所以让运维重启那 4 个节点的服务,消费者重新注册上,消息得以快速消费,消息积压告警得以恢复

生产问题虽暂时得以解决,但未找到根因,还是存在复发风险;下面就请大家跟随我的脚本,来看看我是如何排查的

问题排查

直接查 ERROR 级别的日志,很容易就能就找到了关键日志

Consumer thread error, thread abort.

以及异常堆栈

java.lang.OutOfMemoryError: Requested array size exceeds VM limit
	at java.lang.StringCoding$StringEncoder.encode(StringCoding.java:300)
	at java.lang.StringCoding.encode(StringCoding.java:344)
	at java.lang.String.getBytes(String.java:918)
    ...

Consumer thread error, thread abort 大家能看懂吧,就是字面意思

消费者线程错误,线程中止

消费者线程就是我们前面提到的队列消费者,一个队列消费者就是一个消费者线程,消费者线程中止那就意味着队列消费者中止,也就对应文章标题中的 消费者消失;是不是离真相越来越近了?

OutOfMemoryError 是不是很熟悉,内存溢出嘛

OutOfMemoryError 表示 Java 虚拟机在堆内存中没有足够的空间来分配对象

问你们一个问题:OOM 一定会导致 JVM 退出吗,这个问题你们先思考,后面答案会揭晓

回到正题,从关键日志以及异常堆栈,我们是不是可以得出以下推测

OOM 会导致消费者线程中止

有了推测,那就去验证呗;我先给大家模拟下案例,基于 SpringBootpom.xml 关键依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>

配置文件 application.yml

server:
  port: 8088
spring:
  rabbitmq:
    host: 192.168.2.118
    port: 5672
    username: admin
    password: admin
    virtual-host: /
    listener:
      simple:
        acknowledge-mode: manual #设置确认模式手工确认
        concurrency: 3 #消费者个数,线程个数
        prefetch: 1

RabbitMQ 配置 TaskRabbitConfig.java

package com.qsl.rabbit.config;

import com.qsl.rabbit.constant.Constant;
import com.qsl.rabbit.listener.TaskMessageListener;
import org.springframework.amqp.core.AcknowledgeMode;
import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author: 青石路
 */
@Configuration
public class TaskRabbitConfig {

    @Value("${spring.rabbitmq.listener.simple.concurrency:3}")
    private int concurrency;
    @Value("${spring.rabbitmq.listener.simple.prefetch:1}")
    private int prefetch;

    @Bean
    public DirectExchange taskExchange() {
        return new DirectExchange(Constant.TASK_EXCHANGE, true, false);
    }

    @Bean
    public Queue taskQueue() {
        return new Queue(Constant.TASK_QUEUE, true, false, false);
    }

    @Bean
    public Binding bindingTaskQueue() {
        return BindingBuilder.bind(taskQueue()).to(taskExchange()).with(Constant.TASK_QUEUE);
    }

    @Bean
    public SimpleMessageListenerContainer taskMessageListenerContainer(ConnectionFactory connectionFactory) {

        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        //设置确认模式手工确认
        container.setAcknowledgeMode(AcknowledgeMode.MANUAL);
        container.setQueueNames(Constant.TASK_QUEUE);
        //消费者个数,线程个数
        container.setConcurrentConsumers(concurrency);
        //设置预处理个数
        container.setPrefetchCount(prefetch);

        container.setMessageListener(new TaskMessageListener());
        return container;
    }
}

消息监听器 TaskMessageListener.java

/**
 * @author: 青石路
 */
@Slf4j
public class TaskMessageListener implements ChannelAwareMessageListener {

    @Override
    public void onMessage(Message message, Channel channel) {
        String content = new String(message.getBody(), StandardCharsets.UTF_8);
        log.info("消费者接收到消息:{}", content);
        handleTask(content);
        try {
            // 手动ACK
            channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);
        } catch (IOException e) {
            log.error("消息确认失败,异常:", e);
        }
    }

    private void handleTask(String message) {
        try {
            // 业务处理
            log.info("处理任务:{}", message);
            log.info("任务处理完成");
        } catch (Exception e) {
            log.error("处理任务失败,异常:", e);
        }
    }
}

业务处理的时候进行 Exception 捕获,并且手动确认消息,我相信你们平时都是这么用的,这难道有什么问题?我调整下 handleTask 方法

/**
 * 业务处理
 * @param message 消息内容
 * @author: 青石路
 */
private void handleTask(String message) {
    try {
        // 业务处理
        log.info("处理任务:{}", message);
        int i = 3 / (message.length() % 10);
        if (i == 1) {
            throw new OutOfMemoryError("模拟内存溢出");
        }
        log.info("任务处理结果:{}", i);
    } catch (Exception e) {
        log.error("处理任务失败,异常:", e);
    }
}

启动服务后,队列消费者情况如下

发送消息 a,日志输出如下

2024-09-22 20:15:55|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:a
2024-09-22 20:15:55|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:a
2024-09-22 20:15:55|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|42|任务处理结果:3

相当于业务正常处理;我们再发送消息 abcdefghij,日志输出如下

2024-09-22 20:17:45|taskMessageListenerContainer-3|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:abcdefghij
2024-09-22 20:17:45|taskMessageListenerContainer-3|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:abcdefghij
2024-09-22 20:17:45|taskMessageListenerContainer-3|com.qsl.rabbit.listener.TaskMessageListener|ERROR|44|处理任务失败,异常:
java.lang.ArithmeticException: / by zero
	at com.qsl.rabbit.listener.TaskMessageListener.handleTask(TaskMessageListener.java:38)
	at com.qsl.rabbit.listener.TaskMessageListener.onMessage(TaskMessageListener.java:21)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1591)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1510)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1498)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1489)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1433)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:975)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:921)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1296)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1202)
	at java.lang.Thread.run(Thread.java:748)

被除数为 0,出现 ArithmeticException

相当于业务处理出现了 Exception,而我们进行了 catch,所以日志打印也符合我们的代码逻辑,也不会对消费者线程造成影响,队列消费者还是最初的那 3 个

我们发送消息 ab,日志输出如下

2024-09-22 20:36:31|taskMessageListenerContainer-1|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:ab
2024-09-22 20:36:31|taskMessageListenerContainer-1|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:ab
2024-09-22 20:36:31|taskMessageListenerContainer-1|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|ERROR|1268|Consumer thread error, thread abort.
java.lang.OutOfMemoryError: 模拟内存溢出
	at com.qsl.rabbit.listener.TaskMessageListener.handleTask(TaskMessageListener.java:40)
	at com.qsl.rabbit.listener.TaskMessageListener.onMessage(TaskMessageListener.java:21)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1591)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1510)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1498)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1489)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1433)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:975)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:921)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1296)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1202)
	at java.lang.Thread.run(Thread.java:748)
2024-09-22 20:36:31|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:ab
2024-09-22 20:36:31|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:ab
2024-09-22 20:36:31|taskMessageListenerContainer-2|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|ERROR|1268|Consumer thread error, thread abort.
java.lang.OutOfMemoryError: 模拟内存溢出
	at com.qsl.rabbit.listener.TaskMessageListener.handleTask(TaskMessageListener.java:40)
	at com.qsl.rabbit.listener.TaskMessageListener.onMessage(TaskMessageListener.java:21)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1591)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1510)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1498)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1489)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1433)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:975)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:921)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1296)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1202)
	at java.lang.Thread.run(Thread.java:748)
2024-09-22 20:36:31|taskMessageListenerContainer-3|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:ab
2024-09-22 20:36:31|taskMessageListenerContainer-3|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:ab
2024-09-22 20:36:31|taskMessageListenerContainer-3|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|ERROR|1268|Consumer thread error, thread abort.
java.lang.OutOfMemoryError: 模拟内存溢出
	at com.qsl.rabbit.listener.TaskMessageListener.handleTask(TaskMessageListener.java:40)
	at com.qsl.rabbit.listener.TaskMessageListener.onMessage(TaskMessageListener.java:21)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1591)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1510)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1498)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1489)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1433)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:975)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:921)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1296)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1202)
	at java.lang.Thread.run(Thread.java:748)
2024-09-22 20:36:31|taskMessageListenerContainer-1|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|ERROR|1415|Stopping container from aborted consumer
2024-09-22 20:36:31|taskMessageListenerContainer-1|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|INFO|646|Waiting for workers to finish.
2024-09-22 20:36:31|taskMessageListenerContainer-1|org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer|INFO|649|Successfully waited for workers to finish.

可以看到,除了我们的业务日志,还有 spring 的日志;从日志可以看出,消息一共被消费了 3 次,但无一例外,都消费失败了,每次失败日志都包括

Consumer thread error, thread abort.

Stopping container from aborted consumer

我们再去看下队列消费者情况

我们把这个流程捋一捋

消费者线程 taskMessageListenerContainer-1 收到消息,业务处理的时候 OOM 了,Spring 中止该线程,消息未被手动确认,回到队列等待被消费
消费者线程 taskMessageListenerContainer-2 收到消息,业务处理的时候又 OOM,Spring 中止该线程,消息未被手动确认,回到队列等待被消费
消费者线程 taskMessageListenerContainer-3 收到消息,业务处理的时候扔 OOM,Spring 中止该线程,消息未被手动确认,回到队列等待被消费

全部的 3 个消费者线程都被 Spring 中止了,对应的 3 个队列消费者也就都无了,消息最终回到队列,等待下一个就绪的消费者消费

我们不是 catch 了 Exception 吗,为什么 OutOfMemoryError 还是向上抛给了 Spring ?

OutOfMemoryError 是 Error,并不是 Exception,所以我们的代码并不会捕获 OutOfMemoryError,继续往上抛给了 Spring,而

org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.AsyncMessageProcessingConsumer#run

中有这么一段代码

publishConsumerFailedEvent 发布一个消费者失败事件,事件处理器收到该事件后会中止该线程;这里就不展开讲了,后续我再写一篇源码,给你们好好介绍下 Spring 的中止逻辑

至此,OutOfMemoryError 会导致消费者线程中止,大家都清楚了吧;细心的小伙伴可能会有这样的疑问了

照理来说,生产中 6 个节点的消费者线程不应该都被中止吗,为什么还剩 2 个节点的消费者?

这 2 个节点内存比较充足,所以 JVM 的堆内存配置的比较大,它们的消费者线程在处理消息的时候,并不会 OOM;而当天正好是业务人员在进行历史大数据量处理,几轮操作下来,把那 4 个内存比较小的节点的消费者全干没了,只剩下那 2 个内存比较大的节点的消费者了

根因其实是 OutOfMemoryError,当前只知道是

com.fasterxml.jackson.databind.ObjectMapper#writeValueAsString

这个方法导致的,具体原因还待进一步排查

问题处理

因为 OutOfMemoryError 的原因没找到,并且是在操作历史大数据量这种很少出现的场景中触发 OutOfMemoryError,也没有导致服务重启,所以暂定方式是将 ERROR 也捕获

/**
 * 业务处理
 * @param message 消息内容
 * @author: 青石路
 */
private void handleTask(String message) {
    try {
        // 业务处理
        log.info("处理任务:{}", message);
        int i = 3 / (message.length() % 10);
        if (i == 1) {
            throw new OutOfMemoryError("模拟内存溢出");
        }
        log.info("任务处理结果:{}", i);
    } catch (Exception | Error e) {
        log.error("处理任务失败,异常:", e);
    }
}

重新启动服务,继续消费队列中那条未被消费的消息 ab,此时日志输出如下

2024-09-22 21:38:57|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|20|消费者接收到消息:ab
2024-09-22 21:38:57|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|INFO|37|处理任务:ab
2024-09-22 21:38:57|taskMessageListenerContainer-2|com.qsl.rabbit.listener.TaskMessageListener|ERROR|44|处理任务失败,异常:
java.lang.OutOfMemoryError: 模拟内存溢出
	at com.qsl.rabbit.listener.TaskMessageListener.handleTask(TaskMessageListener.java:40)
	at com.qsl.rabbit.listener.TaskMessageListener.onMessage(TaskMessageListener.java:21)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1591)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1510)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1498)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1489)
	at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1433)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:975)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:921)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1296)
	at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1202)
	at java.lang.Thread.run(Thread.java:748)
2024-09-22 21:38:57|main|com.qsl.rabbit.RabbitmqApplication|INFO|61|Started RabbitmqApplication in 1.045 seconds (JVM running for 1.515)

虽然业务处理仍然失败,但只有符合我们代码逻辑的错误日志输出,并没有 Spring 的错误日志,此时队列消费者情况如下

当然,这只是缓兵之计,最终解决方案还是要分析 OOM 的原因,然后对症下药

总结

  1. 示例代码:spring-boot-rabbitmq

  2. OOM 不一定会导致 JVM 退出,但是 SimpleMessageListenerContainer 会捕获它,然后中止当前线程,对应的队列消费者也就无了

  3. 业务代码 catch Error 虽说只是缓兵之计,但从健壮性考虑的话,也是一个不错的解决办法

    但 OOM 的原因还得继续排查,然后对症下药,这才是最终解决之道

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