mapan1984 commented on PR #23431: URL: https://github.com/apache/kafka/pull/23431#issuecomment-5738620340
> > That metric is currently documented but never implemented; I plan to add the implementation in a follow-up PR. > > Maybe we should have a small KIP to remove it instead. The implementation has been missing for almost 10 years, and no one has complained. The main reason the consumer fetch lag was not implemented in the past was that the consumer didn't provide enough information, and fetching partition end offsets on every poll was too expensive. However, since [KIP-695](https://cwiki.apache.org/confluence/x/JSXZCQ?utm_source=gemini), the `currentLag` method is available, which allows us to query the current consumer lag directly from the local cache. I believe we can now implement this metric using this approach. Furthermore, I believe providing the true consumer lag is valuable for measuring synchronization progress with upstream data. For instance, when using MM2, it is currently very difficult to determine the actual data sync latency. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
