Hello Matthias Thanks for your feedback,
MJS1: I have updated the KIP and added a startup check for Kafka Streams. When to_start_time is configured and the Streams protocol is not enabled, the application will throw a ConfigException at startup, rather than surfacing runtime errors in the background StreamsThread. MJS2: I have bumped the RPC version in the KIP and will also keep an eye on KIP-1071 to avoid version conflicts. MJS3: --to-start-time uses AdminClient throughout the entire flow: describeConsumerGroups() / describeStreamsGroups() to fetch the group creation timestamp, ListOffsets to resolve offsets, and alterConsumerGroupOffsets() / alterStreamsGroupOffsets() to commit offsets. None of these operations go through the consumer protocol directly. So in my opinion, it won't be affected. Best Regards, Jiunn-Yang > Matthias J. Sax <[email protected]> 於 2026年4月16日 上午9:47 寫道： > > Just catching up on this KIP. Couple of questions/comments: > > > MJS1: For Kafka Streams, given that the new policy only works with "streams" > groups, should we add a check at startup if "streams" is actually enabled and > fail early if not (eg throw ConfigException)? -- At least for the config > bases setting this seems doable -- not sure how easy it would be if user set > "to_start_time" programmatically. But maybe also worth to explore? It's much > better UX to fail early IMHO. > > The KIP already mentions this for consumer case, but not for KS. Relying on > the underlying consumer mechanism would result in runtime errors on the > background `StreamsThread` leading to bad UX. > > > MJS2: We recently found a bug in KIP-1071 which requires us to bump the > heartbeat request/response version, too. There is already a draft PR that I > hope to get merged this or next week: > https://github.com/apache/kafka/pull/21799 --- more like an FYI to avoid > confusion -- not sure if we should cross-reference both KIPs to each other > about it? I did not update KIP-1071 yet, but plan to so this before we can > merge the draft PR. > > > MJS3: Recently, we had a discussion about `bin/kafka-consumer-groups.sh`, and > Andrew highlighted that this tool always uses "classic" protocol to commit > offsets (what is not a problem in the strict sense, because "mixed" group are > supported, as pointed out by David J). So I am wondering if introducing the > new `--to-start-time` flag would cause issues? Maybe not, but worth to double > check. > > > -Matthias > > On 4/12/26 3:51 AM, Andrew Schofield wrote: >> Hi Jiunn-Yang, >> Absolutely no need to apologise for non-native English :) There were many >> review cycles before it was evident that to_ was slightly better than by_. >> The KIP looks great now. >> Thanks, >> Andrew >> On 2026/04/11 08:57:37 黃竣陽 wrote: >>> Hello Andrew, >>> >>> Apologies in advance for my non-native English — please bear with me :) >>> >>> Thanks for the clarification on AS13. After thinking it through, I agree >>> that >>> to_start_time is a better name than by_start_time. Your reasoning is >>> convincing: >>> by_duration computes a relative time (now - duration), while the new policy >>> anchors to an absolute, server-recorded timestamp (the group creation time). >>> The to_* prefix correctly conveys “seek to a fixed point”. >>> >>> Best Regards, >>> Jiunn-Yang >>> >>>> Andrew Schofield <[email protected]> 於 2026年4月11日 下午4:20 寫道： >>>> >>>> Hi Jiunn-Yang, >>>> Thanks for the updates. >>>> >>>> AS12: Thanks. >>>> >>>> AS13: I did actually mean to change all of the by_start_time, byStartTime >>>> and --by-start-time variants across the entire KIP to to_start_time, >>>> toStartTime and --to-start-time. I did say it was quite pervasive, which >>>> is why I said you could ignore the suggestion :) >>>> >>>> AS14: Thanks. >>>> >>>> Thanks, >>>> Andrew >>>> >>>> On 2026/04/11 02:13:19 黃竣陽 wrote: >>>>> Hello Andrew, >>>>> >>>>> Thanks for the helpful feedback. >>>>> >>>>> AS12: GROUP-CREATION-TIME is now only shown in --describe --state —verbose >>>>> output. This avoids cluttering the default output for normal users. >>>>> >>>>> AS13: Addressed in the KIP. >>>>> >>>>> AS14: Applied the same changes to kafka-streams-groups.sh. Both >>>>> --describe --state —verbose >>>>> and --reset-offsets --to-start-time are now supported for streams groups >>>>> as well. >>>>> >>>>> Best Regards, >>>>> Jiunn-Yang >>>>> >>>>>> Andrew Schofield <[email protected]> 於 2026年4月11日 清晨5:17 寫道： >>>>>> >>>>>> A few more comments I'm afraid. >>>>> >>>>> >>> >>> >
