Thanks for the update Crispin - very helpful to have actual performance data. 2-5% for the default configuration is a bit on the low side for this kind of proposal.
Ismael On Thu, Jul 20, 2023 at 11:33 PM Crispin Bernier <cbern...@confluent.io.invalid> wrote: > Benchmark numbers have been posted on the KIP, please review. > > On 2023/07/20 13:03:00 Mayank Shekhar Narula wrote: > > Jun > > > > Thanks for the feedback. > > > > Numbers to follow. > > > > If we don't plan to > > > bump up the FetchResponse version, we could just remove the reference > to > > > version 16. > > > > Fixed. > > > > On Thu, Jul 20, 2023 at 1:28 AM Jun Rao <ju...@confluent.io.invalid> > wrote: > > > > > Hi, Mayank, > > > > > > Thanks for the KIP. I agree with others that it would be useful to see > the > > > performance results. Otherwise, just a minor comment. If we don't plan > to > > > bump up the FetchResponse version, we could just remove the reference > to > > > version 16. > > > > > > Jun > > > > > > On Wed, Jul 19, 2023 at 2:31 PM Mayank Shekhar Narula < > > > mayanks.nar...@gmail.com> wrote: > > > > > > > Luke > > > > > > > > Thanks for the interest in the KIP. > > > > > > > > But what if the consumer was fetching from the follower? > > > > > > > > We already include `PreferredReadReplica` in the fetch response. > > > > > Should we put the node info of PreferredReadReplica under this > case, > > > > > instead of the leader's info? > > > > > > > > > > > > > PreferredReadReplica is the decided on the leader. Looking at the > Java > > > > client code, AbstractFetch::selectReadReplica, first fetch request > goes > > > to > > > > Leader of the partition -> Sends back PreferredReadReplica -> Next > fetch > > > > uses PreferredReadReplica. So as long as leader is available, > > > > PreferredReadReplica would be found in subsequent fetches. > > > > > > > > Also, under this case, should we include the leader's info in the > > > response? > > > > > > > > > > > > In this case, I think the follower would fail the fetch if it knows a > > > > different leader. If the follower knows a newer leader, it would > return > > > new > > > > leader information in the response, for the client to act on. > > > > > > > > > > > > Will we include the leader/node info in the response when having > > > > > `UNKNOWN_LEADER_EPOCH` error? > > > > > > > > > > > > My understanding is UNKNOWN_LEADER_EPOCH when a request from a client > > > has a > > > > newer epoch than the broker. So the client is already up to date on > new > > > > leader information, it's the broker that has the catching up to do. I > > > think > > > > there might be some optimisations to make sure the broker refreshes > its > > > > metadata quickly, so it can quickly recover to handle requests that > > > > previously returned UNKNOWN_LEADER_EPOCH. But this work is outside > the > > > > scope of this KIP, as for now this KIP focusses on client-side > > > > optimisations. > > > > > > > > Mayank > > > > > > > > On Tue, Jul 18, 2023 at 8:51 AM Luke Chen <sh...@gmail.com> wrote: > > > > > > > > > Hi Mayank, > > > > > > > > > > Thanks for the KIP! > > > > > > > > > > Some questions: > > > > > 1. I can see most of the cases we only care about consumer fetch > from > > > the > > > > > leader. > > > > > But what if the consumer was fetching from the follower? > > > > > We already include `PreferredReadReplica` in the fetch response. > > > > > Should we put the node info of PreferredReadReplica under this > case, > > > > > instead of the leader's info? > > > > > Also, under this case, should we include the leader's info in the > > > > response? > > > > > > > > > > 2. Will we include the leader/node info in the response when having > > > > > `UNKNOWN_LEADER_EPOCH` error? > > > > > I think it's fine we ignore the `UNKNOWN_LEADER_EPOCH` error since > when > > > > > this happens, the node might have some error which should refresh > the > > > > > metadata. On the other hand, it might also be good if we can heal > the > > > > node > > > > > soon to do produce/consume works. > > > > > > > > > > > > > > > Thank you. > > > > > Luke > > > > > > > > > > On Tue, Jul 18, 2023 at 2:00 AM Philip Nee <ph...@gmail.com> > > > wrote: > > > > > > > > > > > Hey Mayank: > > > > > > > > > > > > For #1: I think fetch and produce behave a bit differently on > > > metadata. > > > > > > Maybe it is worth highlighting the changes for each client in > detail. > > > > In > > > > > > producer did you mean by the metadata timeout before sending out > > > > produce > > > > > > requests? For consumer: I think for fetches it requires user to > retry > > > > if > > > > > > the position does not exist on the leader. I don't have the > detail on > > > > top > > > > > > of my head, but I think we should lay out these behavioral > changes. > > > > > > > > > > > > For #3: Thanks for the clarification. > > > > > > > > > > > > On Mon, Jul 17, 2023 at 10:39 AM Mayank Shekhar Narula < > > > > > > mayanks.nar...@gmail.com> wrote: > > > > > > > > > > > > > Philip > > > > > > > > > > > > > > 1. Good call out about "poll" behaviour, my understanding is > the > > > > same. > > > > > I > > > > > > am > > > > > > > assuming it's about the motivation of the KIP. There with > async, my > > > > > > > intention was to convey that the client doesn't wait for the > > > > > > > metadata-refresh before a subsequent retry of the produce or > fetch > > > > > > request > > > > > > > that failed due to stale metadata(i.e. going to an old > leader). The > > > > > only > > > > > > > wait client has is the configured retry-delay. > > > > > > > > > > > > > > 2. Yes, in theory other APIs could benefit from this too. But > that > > > is > > > > > > > outside of the scope of the KIP. > > > > > > > > > > > > > > 3. Do you mean the response for the Metadata RPC? I think > brokers > > > > > always > > > > > > > have a view of the cluster, although it can be stale,it would > > > always > > > > > > return > > > > > > > a leader(whether old or new). > > > > > > > > > > > > > > Mayank > > > > > > > > > > > > > > On Fri, Jul 14, 2023 at 8:53 PM Philip Nee <ph...@gmail.com> > > > > > wrote: > > > > > > > > > > > > > > > Hey Mayank, > > > > > > > > > > > > > > > > Thanks for the KIP. I think this is a great proposal, and > I'm in > > > > > favor > > > > > > > > of this idea. A few comments: > > > > > > > > > > > > > > > > 1. Claiming metadata refresh is done asynchronously is > > > misleading. > > > > > The > > > > > > > > metadata refresh requires Network Client to be physically > polled, > > > > > which > > > > > > > is > > > > > > > > done in a separate thread in Producer and Admin Client > (IIRC!) > > > but > > > > > not > > > > > > > > Consumer. > > > > > > > > 2. There are other API calls that might result in > > > > > > NOT_LEADER_OR_FOLLOWER > > > > > > > > response, but it seems like this KIP only wants to update on > > > fetch > > > > > and > > > > > > > > produce. Do we want to make the leader information available > for > > > > > other > > > > > > > API > > > > > > > > calls? > > > > > > > > 3. Do you know what would happen during a leader election? > I'm > > > not > > > > > sure > > > > > > > > about this process and I wonder if the current metadata > response > > > > uses > > > > > > the > > > > > > > > old leader or null as the leader isn't readily available yet. > > > > > > > > > > > > > > > > Thanks, > > > > > > > > P > > > > > > > > > > > > > > > > On Fri, Jul 14, 2023 at 11:30 AM Kirk True < > ki...@kirktrue.pro> > > > > > wrote: > > > > > > > > > > > > > > > > > Hi Mayank, > > > > > > > > > > > > > > > > > > > On Jul 14, 2023, at 11:25 AM, Mayank Shekhar Narula < > > > > > > > > > mayanks.nar...@gmail.com> wrote: > > > > > > > > > > > > > > > > > > > > Kirk > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >> Is the requested restructuring of the response “simply” > to > > > > > > preserve > > > > > > > > > bytes, > > > > > > > > > >> or is it possible that the fetch response > could/should/would > > > > > > return > > > > > > > > > >> leadership changes for partitions that we’re > specifically > > > > > > requested? > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > Moving endpoints to top-level fields would preserve > bytes, > > > > > > otherwise > > > > > > > > the > > > > > > > > > > endpoint-information would be duplicated if included > with the > > > > > > > > > > partition-data in the response. Right now, the top-level > > > field > > > > > will > > > > > > > > only > > > > > > > > > be > > > > > > > > > > set in case leader changes for any requested partitions. > But > > > it > > > > > can > > > > > > > be > > > > > > > > > > re-used in the future, for which Jose has a use-case in > mind > > > > > shared > > > > > > > up > > > > > > > > in > > > > > > > > > > the thread. KIP is now upto date with endpoint info > being at > > > > > > > top-level. > > > > > > > > > > > > > > > > > > > > > > > > > > > I didn’t catch before that there was a separate section > for the > > > > > full > > > > > > > node > > > > > > > > > information, not just the ID and epoch. > > > > > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > > > > > > >>> 3. In the future, I may use this information in the > > > > > > KRaft/Metadata > > > > > > > > > >>> implementation of FETCH. In that implementation not > all of > > > > the > > > > > > > > > >>> replicas are brokers. > > > > > > > > > >> > > > > > > > > > >> Side point: any references to the change you’re > referring > > > to? > > > > > The > > > > > > > idea > > > > > > > > > of > > > > > > > > > >> non-brokers serving as replicas is blowing my mind a > bit :) > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > > Jose, I missed this as well, would love to know more > about > > > > > > non-broker > > > > > > > > > > serving as replica! > > > > > > > > > > -- > > > > > > > > > > Regards, > > > > > > > > > > Mayank Shekhar Narula > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > Regards, > > > > > > > Mayank Shekhar Narula > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > Regards, > > > > Mayank Shekhar Narula > > > > > > > > > > > > > -- > > Regards, > > Mayank Shekhar Narula > >
