RocketMQ-Retry_rocketmq retry topic

Retry队列是什么

当消息消费失败时，消费者会将消息发往retry队列，等待重试

Retry队列的命名方式为：%RETRY%GROUP_NAME，也就是说每个消费组都会有自己独立的Retry队列

生产逻辑

RequestCode:CONSUMER_SEND_MSG_BACK
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脉络图如下：

Client端

Concurrently模式

在以下几种情况下会向Retry队列发送该条消息

1. 当消息消费失败返回RECONSUME_LATER，并且是Clustering模式时
2. 清理本地超时消息（已拉取缓存在内存中的消息）

public void processConsumeResult(
    final ConsumeConcurrentlyStatus status,
    final ConsumeConcurrentlyContext context,
    final ConsumeRequest consumeRequest
) {
   
    switch (this.defaultMQPushConsumer.getMessageModel()) {
   
        case BROADCASTING:
            for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
   
                MessageExt msg = consumeRequest.getMsgs().get(i);
                log.warn("BROADCASTING, the message consume failed, drop it, {}", msg.toString());
            }
            break;
        case CLUSTERING:
            List<MessageExt> msgBackFailed = new ArrayList<MessageExt>(consumeRequest.getMsgs().size()
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