Hello Luke, Thanks for the updated KIP, I've taken a look at it and still LGTM. Just a couple minor comments in the wiki:
* Both `StickyAssignor` and `CooperativeStickyAssignor` that there's already generation is encoded in user-data bytes, the difference is that the `StickyAssignor`'s user bytes also encode the prev-owned partitions while the `CooperativeStickyAssignor` relies on the prev-owned partitions on the subscription protocol directly. So we can add the `StickyAssignor` in your paragraph talking about `CooperativeStickyAssignor` as well. * This sentence: "otherwise, we'll take the ownedPartitions as default generation(-1)." does not read right to me, maybe need to rephrase a bit? Guozhang On Mon, Feb 7, 2022 at 7:36 PM Luke Chen <show...@gmail.com> wrote: > Hi David, > > Thanks for your comments. > I've updated the KIP to add changes in Subscription class. > > Thank you. > Luke > > On Fri, Feb 4, 2022 at 11:43 PM David Jacot <dja...@confluent.io.invalid> > wrote: > > > Hi Luke, > > > > Thanks for updating the KIP. I just have a minor request. > > Could you fully describe the changes to the Subscription > > public class in the KIP? I think that it would be better than > > just saying that the generation will be added to id. > > > > Otherwise, the KIP LGTM. > > > > Thanks, > > David > > > > On Mon, Nov 29, 2021 at 4:29 AM Luke Chen <show...@gmail.com> wrote: > > > > > > Hi devs, > > > Welcome to provide feedback. > > > > > > If there are no other comments, I'll start a vote tomorrow. > > > > > > Thank you. > > > Luke > > > > > > > > > On Mon, Nov 22, 2021 at 4:16 PM Luke Chen <show...@gmail.com> wrote: > > > > > > > Hello David, > > > > > > > > For (3): > > > > > > > > > > > > > > > > * I suppose that we could add a `generation` field to the > > JoinGroupRequest > > > > instead to do the fencing that you describe while handling the > > sentinel in > > > > the assignor directly. If we would add the `generation` to the > request > > > > itself, would we need the `generation` in the subscription protocol > as > > > > well?* > > > > > > > > On second thought, I think this is not better than adding > `generation` > > > > field in the subscription protocol, because I think we don't have to > > do any > > > > generation validation on joinGroup request. The purpose of > > > > `joinGroupRequest` is to accept any members to join this group, even > > if the > > > > member is new or ever joined or what. As long as we have the > > generationId > > > > in the subscription metadata, the consumer lead can leverage the info > > to > > > > ignore the old ownedPartitions (or do other handling), and the > > rebalance > > > > can still complete successfully and correctly. On the other hand, if > > we did > > > > the generation check on JoinGroupRequest, and return > > `ILLEGAL_GENERATION` > > > > back to consumer, the consumer needs to clear its generation info and > > > > rejoin the group to continue the rebalance. It needs more > > request/response > > > > network and slow down the rebalance. > > > > > > > > So I think we should add the `generationId` field into Subscription > > > > protocol to achieve what we want. > > > > > > > > Thank you. > > > > Luke > > > > > > > > On Thu, Nov 18, 2021 at 8:51 PM Luke Chen <show...@gmail.com> wrote: > > > > > > > >> Hi David, > > > >> Thanks for your feedback. > > > >> > > > >> I've updated the KIP for your comments (1)(2). > > > >> For (3), it's a good point! Yes, we didn't deserialize the > > subscription > > > >> metadata on broker side, and it's not necessary to add overhead on > > broker > > > >> side. And, yes, I think we can fix the original issue by adding a > > > >> "generation" field into `JoinGroupRequest` instead, and also add a > > field > > > >> into `JoinGroupResponse` in `JoinGroupResponseMember` field. That > > way, the > > > >> broker can identify the old member from `JoinGroupRequest`. And the > > > >> assignor can also get the "generation" info via the `Subscription` > > instance. > > > >> > > > >> I'll update the KIP to add "generation" field into > `JoinGroupRequest` > > and > > > >> `JoinGroupResponse`, if there is no other options. > > > >> > > > >> Thank you. > > > >> Luke > > > >> > > > >> > > > >> On Tue, Nov 16, 2021 at 12:31 AM David Jacot > > <dja...@confluent.io.invalid> > > > >> wrote: > > > >> > > > >>> Hi Luke, > > > >>> > > > >>> Thanks for the KIP. Overall, I think that the motivation makes > > sense. I > > > >>> have a couple of comments/questions: > > > >>> > > > >>> 1. In the Public Interfaces section, it would be great if you could > > put > > > >>> the > > > >>> end state not the current one. > > > >>> > > > >>> 2. Do we need to update the Subscription class to expose the > > > >>> generation? If so, it would be great to mention it in the Public > > > >>> Interfaces section as well. > > > >>> > > > >>> 3. You mention that the broker will set the generation if the > > > >>> subscription > > > >>> contains a sentinel value (-1). As of today, the broker does not > > parse > > > >>> the subscription so I am not sure how/why we would do this. I > suppose > > > >>> that we could add a `generation` field to the JoinGroupRequest > > instead > > > >>> to do the fencing that you describe while handling the sentinel in > > the > > > >>> assignor directly. If we would add the `generation` to the request > > > >>> itself, > > > >>> would we need the `generation` in the subscription protocol as > well? > > > >>> > > > >>> Best, > > > >>> David > > > >>> > > > >>> On Fri, Nov 12, 2021 at 3:31 AM Luke Chen <show...@gmail.com> > wrote: > > > >>> > > > > >>> > Hi all, > > > >>> > > > > >>> > I'd like to start the discussion for KIP-792: Add "generation" > > field > > > >>> into > > > >>> > consumer protocol. > > > >>> > > > > >>> > The goal of this KIP is to allow assignor/consumer > > coordinator/group > > > >>> > coordinator to have a way to identify the out-of-date > > > >>> members/assignments. > > > >>> > > > > >>> > Detailed description can be found here: > > > >>> > > > > >>> > > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=191336614 > > > >>> > > > > >>> > Any feedback is welcome. > > > >>> > > > > >>> > Thank you. > > > >>> > Luke > > > >>> > > > >> > > > -- -- Guozhang
