humkum opened a new issue, #9307: URL: https://github.com/apache/rocketmq/issues/9307
### Before Creating the Bug Report - [x] I found a bug, not just asking a question, which should be created in [GitHub Discussions](https://github.com/apache/rocketmq/discussions). - [x] I have searched the [GitHub Issues](https://github.com/apache/rocketmq/issues) and [GitHub Discussions](https://github.com/apache/rocketmq/discussions) of this repository and believe that this is not a duplicate. - [x] I have confirmed that this bug belongs to the current repository, not other repositories of RocketMQ. ### Runtime platform environment CentOS7.10 ### RocketMQ version develop ### JDK Version 1.8 ### Describe the Bug There may be message loss if we expand the topic to the new broker while the consumer stops for a while. The consumer would consume from the max offset of queues in new broker, which didn't have the consumption offset of the consumer. ### Steps to Reproduce 1. The consumer was stopped a while, or the sdk has a bug that unable to perceive topic route changes. 2. Expand topic to new broker, consume offset not yet generated. 3. Produce messages for a long time. 4. (Re)Start the consumer. ### What Did You Expect to See? The consumer can consume all messages in new broker expanded. ### What Did You See Instead? The consumer consume from the max offset, some messages were skipped. ### Additional Context After investigation, it is found that when the consumption position does not exist on the broker of the server side, the server will check if the difference between the maximum position of the commitLog and the physical offset of the message corresponding to the consumption offset exceeds 40% of the memory size. If so, an exception will be thrown and the consumption offset will not be returned. When the consumption client cannot obtain the consumption offset, it will obtain the maxOffset for consumption according to the default configuration of ConsumeFromWhere on the client side.   -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@rocketmq.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
