Thanks Luke, in that case I'm +1 on this KIP. On Thu, Dec 9, 2021 at 1:46 AM Luke Chen <show...@gmail.com> wrote:
> Hi Guozhang, > > Thanks for your comment. > > > we need to make sure the old-versioned leader would be able to ignore the > new > field during an upgrade e.g. without crashing. > > Yes, I understand. I'll be careful to make sure it won't crash the old > versioned leader. > But basically, it won't, because we appended the new field into the last of > the ConsumerProtocolSubscription, which means, when read/deserialize the > Subscription metadata, the old versioned leader will just read the head > part of the data. > > Thanks for the reminder! > > Luke > > On Thu, Dec 9, 2021 at 4:00 AM Guozhang Wang <wangg...@gmail.com> wrote: > > > Hi Luke, > > > > Thanks for the KIP. > > > > One thing I'd like to double check is that, since the > > ConsumerProtocolSubscription is not auto generated from the json file, we > > need to make sure the old-versioned leader would be able to ignore the > new > > field during an upgrade e.g. without crashing. Other than that, the KIP > > lgtm. > > > > Guozhang > > > > On Tue, Dec 7, 2021 at 6:16 PM Luke Chen <show...@gmail.com> wrote: > > > > > Hi Colin, > > > > > > I'm not quite sure if I understand your thoughts correctly. > > > If I was wrong, please let me know. > > > > > > Also, I'm not quite sure how I could lock this feature to a new IBP > > > version. > > > I saw "KIP-584: Versioning scheme for features" is still under > > development. > > > Not sure if I need to lock the IBP version, how should I do? > > > > > > Thank you. > > > Luke > > > > > > On Tue, Dec 7, 2021 at 9:41 PM Luke Chen <show...@gmail.com> wrote: > > > > > > > Hi Colin, > > > > > > > > Thanks for your comments. I've updated the KIP to mention about the > KIP > > > > won't affect current broker side behavior. > > > > > > > > > One scenario that we need to consider is what happens during a > > rolling > > > > upgrade. If the coordinator moves back and forth between brokers with > > > > different IBPs, it seems that the same epoch numbers could be reused > > for > > > a > > > > group, if things are done in the obvious manner (old IBP = don't read > > or > > > > write epoch, new IBP = do) > > > > > > > > I think this KIP doesn't care about the group epoch number at all. > The > > > > subscription metadata is passed from each member to group > coordinator, > > > and > > > > then the group coordinator pass all of them back to the consumer > lead. > > So > > > > even if the epoch number is reused in a group, it should be fine. On > > the > > > > other hand, the group coordinator will have no idea if the join group > > > > request sent from consumer containing the new subscription > "generation" > > > > field or not, because group coordinator won't deserialize the > metadata. > > > > > > > > I've added also added them into the KIP. > > > > > > > > Thank you. > > > > Luke > > > > > > > > On Mon, Dec 6, 2021 at 10:39 AM Colin McCabe <cmcc...@apache.org> > > wrote: > > > > > > > >> Hi Luke, > > > >> > > > >> Thanks for the explanation. > > > >> > > > >> I don't see any description of how the broker decides to use the new > > > >> version of ConsumerProtocolSubscription or not. This probably needs > to > > > be > > > >> locked to a new IBP version. > > > >> > > > >> One scenario that we need to consider is what happens during a > rolling > > > >> upgrade. If the coordinator moves back and forth between brokers > with > > > >> different IBPs, it seems that the same epoch numbers could be reused > > > for a > > > >> group, if things are done in the obvious manner (old IBP = don't > read > > or > > > >> write epoch, new IBP = do). > > > >> > > > >> best, > > > >> Colin > > > >> > > > >> > > > >> On Fri, Dec 3, 2021, at 18:46, Luke Chen wrote: > > > >> > Hi Colin, > > > >> > Thanks for your comment. > > > >> > > > > >> >> How are we going to avoid the situation where the broker > restarts, > > > and > > > >> > the same generation number is reused? > > > >> > > > > >> > Actually, this KIP doesn't have anything to do with the brokers. > The > > > >> > "generation" field I added, is in the subscription metadata, which > > > will > > > >> not > > > >> > be deserialized by brokers. The metadata is only deserialized by > > > >> consumer > > > >> > lead. And for the consumer lead, the only thing the lead cared > > about, > > > is > > > >> > the highest generation of the ownedPartitions among all the > > consumers. > > > >> With > > > >> > the highest generation of the ownedPartitions, the consumer lead > can > > > >> > distribute the partitions as sticky as possible, and most > > importantly, > > > >> > without errors. > > > >> > > > > >> > That is, after this KIP, if the broker restarts, and the same > > > generation > > > >> > number is reused, it won't break current rebalance behavior. But > > it'll > > > >> help > > > >> > the consumer lead do the sticky assignments correctly. > > > >> > > > > >> > Thank you. > > > >> > Luke > > > >> > > > > >> > On Fri, Dec 3, 2021 at 6:30 AM Colin McCabe <co...@cmccabe.xyz> > > > wrote: > > > >> > > > > >> >> How are we going to avoid the situation where the broker > restarts, > > > and > > > >> the > > > >> >> same generation number is reused? > > > >> >> > > > >> >> best, > > > >> >> Colin > > > >> >> > > > >> >> On Tue, Nov 30, 2021, at 16:36, Luke Chen wrote: > > > >> >> > Hi all, > > > >> >> > > > > >> >> > I'd like to start the vote for KIP-792: Add "generation" field > > into > > > >> >> > consumer protocol. > > > >> >> > > > > >> >> > The goal of this KIP is to allow the assignor/consumer > > coordinator > > > to > > > >> >> have > > > >> >> > a way to identify the out-of-date members/assignments, to avoid > > > >> rebalance > > > >> >> > stuck issues in current protocol. > > > >> >> > > > > >> >> > Detailed description can be found here: > > > >> >> > > > > >> >> > > > >> > > > > > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=191336614 > > > >> >> > > > > >> >> > Any feedback is welcome. > > > >> >> > > > > >> >> > Thank you. > > > >> >> > Luke > > > >> >> > > > >> > > > > > > > > > > > > > -- > > -- Guozhang > > > -- -- Guozhang
