Overall, agree on point #1, less sure on point #2. 1. Some protocols never ever add new errors, while others add errors without bumping versions. HTTP is a good example of the second type. HTTP-451 was added fairly recently, there are some errors specific to NGINX, etc. No one cares. I think we should properly document in the wire-protocol doc that new errors can be added, and I think we should strongly suggest (and implement ourselves) that unknown error codes should be shown to users (or at least logged), so they can be googled and understood through our documentation. In addition, hierarchy of error codes, so clients will know if an error is retry-able just by looking at the code could be nice. Same for adding an error string to the protocol. These are future enhancements that should be discussed separately.
2. I think we want to allow admins to upgrade their Kafka brokers without having to chase down clients in their organization and without getting blamed if clients break. I think it makes sense to have one version that will support existing behavior, but log warnings, so admins will know about misbehaving clients and can track them down before an upgrade that breaks them (or before the broken config causes them to lose data!). Hopefully this is indeed a very rare behavior and we are taking extra precaution for nothing, but I have customers where one traumatic upgrade means they will never upgrade a Kafka again, so I'm being conservative. Gwen On Sun, Jan 18, 2015 at 3:50 PM, Jun Rao <j...@confluent.io> wrote: > Overall, I agree with Jay on both points. > > 1. I think it's reasonable to add new error codes w/o bumping up the > protocol version. In most cases, by adding new error codes, we are just > refining the categorization of those unknown errors. So, a client shouldn't > behave worse than before as long as unknown errors have been properly > handled. > > 2. I think it's reasonable to just document that 0.8.2 will be the last > release that will support ack > 1 and remove the support completely in trunk > w/o bumping up the protocol. This is because (a) we never included ack > 1 > explicitly in the documentation and so the usage should be limited; (2) ack >> 1 doesn't provide the guarantee that people really want and so it > shouldn't really be used. > > Thanks, > > Jun > > > On Sun, Jan 18, 2015 at 11:03 AM, Jay Kreps <jay.kr...@gmail.com> wrote: >> >> Hey guys, >> >> I really think we are discussing two things here: >> >> How should we generally handle changes to the set of errors? Should >> introducing new errors be considered a protocol change or should we reserve >> the right to introduce new error codes? >> Given that this particular change is possibly incompatible, how should we >> handle it? >> >> I think it would be good for people who are responding here to be specific >> about which they are addressing. >> >> Here is what I think: >> >> 1. Errors should be extensible within a protocol version. >> >> We should change the protocol documentation to list the errors that can be >> given back from each api, their meaning, and how to handle them, BUT we >> should explicitly state that the set of errors are open ended. That is we >> should reserve the right to introduce new errors and explicitly state that >> clients need a blanket "unknown error" handling mechanism. The error can >> link to the protocol definition (something like "Unknown error 42, see >> protocol definition at http://link";). We could make this work really well by >> instructing all the clients to report the error in a very googlable way as >> Oracle does with their error format (e.g. "ORA-32") so that if you ever get >> the raw error google will take you to the definition. >> >> I agree that a more rigid definition seems like "right thing", but having >> just implemented two clients and spent a bunch of time on the server side, I >> think, it will work out poorly in practice. Here is why: >> >> I think we will make a lot of mistakes in nailing down the set of error >> codes up front and we will end up going through 3-4 churns of the protocol >> definition just realizing the set of errors that can be thrown. I think this >> churn will actually make life worse for clients that now have to figure out >> 7 identical versions of the protocol and will be a mess in terms of testing >> on the server side. I actually know this to be true because while >> implementing the clients I tried to guess the errors that could be thrown, >> then checked my guess by close code inspection. It turned out that I always >> missed things in my belief about errors, but more importantly even after >> close code inspection I found tons of other errors in my stress testing. >> In practice error handling always involves calling out one or two >> meaningful failures that have special recovery and then a blanket case that >> just handles everything else. It's true that some clients may not have done >> this well, but I think it is for the best if they fix that. >> Reserving the right to add errors doesn't mean we will do it without care. >> We will think through each change and decide whether giving a little more >> precision in the error is worth the overhead and churn of a protocol version >> bump. >> >> 2. In this case in particular we should not introduce a new protocol >> version >> >> In this particular case we are saying that acks > 1 doesn't make sense and >> we want to give an error to people specifying this so that they change their >> configuration. This is a configuration that few people use and we want to >> just make it an error. The bad behavior will just be that the error will not >> be as good as it could be. I think that is a better tradeoff than >> introducing a separate protocol version (this may be true of the java >> clients too). >> >> We will have lots of cases like this in the future and we aren't going to >> want to churn the protocol for each of them. For example we previously had >> to get more precise about which characters were legal and which illegal in >> topic names. >> >> -Jay >> >> On Fri, Jan 16, 2015 at 11:55 AM, Gwen Shapira <gshap...@cloudera.com> >> wrote: >>> >>> I updated the KIP: Using acks > 1 in version 0 will log a WARN message >>> in the broker about client using deprecated behavior (suggested by Joe >>> in the JIRA, and I think it makes sense). >>> >>> Gwen >>> >>> On Fri, Jan 16, 2015 at 10:40 AM, Gwen Shapira <gshap...@cloudera.com> >>> wrote: >>> > How about we continue the discussion on this thread, so we won't lose >>> > the context of this discussion, and put it up for VOTE when this has >>> > been finalized? >>> > >>> > On Fri, Jan 16, 2015 at 10:22 AM, Neha Narkhede <n...@confluent.io> >>> > wrote: >>> >> Gwen, >>> >> >>> >> KIP write-up looks good. According to the rest of the KIP process >>> >> proposal, >>> >> would you like to start a DISCUSS/VOTE thread for it? >>> >> >>> >> Thanks, >>> >> Neha >>> >> >>> >> On Fri, Jan 16, 2015 at 9:37 AM, Ewen Cheslack-Postava >>> >> <e...@confluent.io> >>> >> wrote: >>> >> >>> >>> Gwen -- KIP write up looks good. Deprecation schedule probably needs >>> >>> to be >>> >>> more specific, but I think that discussion probably needs to happen >>> >>> after a >>> >>> solution is agreed upon. >>> >>> >>> >>> Jay -- I think "older clients will get a bad error message instead of >>> >>> a >>> >>> good one" isn't what would be happening with this change. Previously >>> >>> they >>> >>> wouldn't have received an error and they would have been able to >>> >>> produce >>> >>> messages. After the change they'll just receive this new error >>> >>> message >>> >>> which their clients can't possibly handle gracefully since it didn't >>> >>> exist >>> >>> when the client was written. Whether the acks > 1 setting was >>> >>> actually >>> >>> accomplishing what they thought doesn't matter. Someone could have >>> >>> reasonably read the docs on 0.8.1.1, thought acks = 2 is an ok >>> >>> setting for >>> >>> their applications, set it as a default across a bunch of apps, then >>> >>> follow >>> >>> the recommended upgrade path of updating brokers to 0.8.2 and all >>> >>> their >>> >>> apps will start failing on produce requests. >>> >>> >>> >>> >>> >>> On Thu, Jan 15, 2015 at 8:27 PM, Jay Kreps <jay.kr...@gmail.com> >>> >>> wrote: >>> >>> >>> >>> > This is a good case to discuss. >>> >>> > >>> >>> > Let's figure the general case of how we want to handle errors and >>> >>> > get >>> >>> that >>> >>> > documented in the protocol. The problem right now is that we give >>> >>> > no >>> >>> > guidance on this. I actually thought Gwen's suggestion made sense >>> >>> > on the >>> >>> > guidance we should have given which is that we will enumerate a set >>> >>> > of >>> >>> > errors and their meaning for each API but it is possible that other >>> >>> errors >>> >>> > will occur and they should be handled (maybe poorly) in the same >>> >>> > way >>> >>> > UNKNOWN_ERROR is handled which is our normal escape hatch for >>> >>> > things like >>> >>> > OOMException. >>> >>> > >>> >>> > I really do think we shouldn't be dogmatic here: In considering a >>> >>> > change >>> >>> > to errors we should consider the potential ill-effect vs the >>> >>> > complexity >>> >>> of >>> >>> > yet another protocol version. >>> >>> > >>> >>> > In this case I actually am not sure we need to bump the protocol >>> >>> > because >>> >>> > the whole point of the change was to make a setting we think >>> >>> > doesn't make >>> >>> > sense break, right? Well this will break it. It seems like the only >>> >>> > downside is that older clients will get a bad error message instead >>> >>> > of a >>> >>> > good one. But it isn't like we will have rendered a client >>> >>> > unusable, it >>> >>> is >>> >>> > just that they will need to change their config. >>> >>> > >>> >>> > -Jay >>> >>> > >>> >>> > On Thu, Jan 15, 2015 at 6:14 PM, Gwen Shapira >>> >>> > <gshap...@cloudera.com> >>> >>> > wrote: >>> >>> > >>> >>> >> I created a KIP for this suggestion: >>> >>> >> >>> >>> >> >>> >>> >> >>> >>> >>> >>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-1+-+Remove+support+of+request.required.acks >>> >>> >> >>> >>> >> Basically documenting what was already discussed here. Comments >>> >>> >> will >>> >>> >> be awesome! >>> >>> >> >>> >>> >> Gwen >>> >>> >> >>> >>> >> On Thu, Jan 15, 2015 at 5:19 PM, Gwen Shapira >>> >>> >> <gshap...@cloudera.com> >>> >>> >> wrote: >>> >>> >> > The errors are part of the KIP process now, so I think the >>> >>> >> > clients are >>> >>> >> safe :) >>> >>> >> > >>> >>> >> > >>> >>> >> >>> >>> >>> >>> https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals >>> >>> >> > >>> >>> >> > On Thu, Jan 15, 2015 at 5:12 PM, Steve Morin >>> >>> >> > <steve.mo...@gmail.com> >>> >>> >> wrote: >>> >>> >> >> Agree errors should be part of the protocol >>> >>> >> >> >>> >>> >> >>> On Jan 15, 2015, at 17:59, Gwen Shapira >>> >>> >> >>> <gshap...@cloudera.com> >>> >>> >> wrote: >>> >>> >> >>> >>> >>> >> >>> Hi, >>> >>> >> >>> >>> >>> >> >>> I got convinced by Joe and Dana that errors are indeed part of >>> >>> >> >>> the >>> >>> >> >>> protocol and can't be randomly added. >>> >>> >> >>> >>> >>> >> >>> So, it looks like we need to bump version of ProduceRequest in >>> >>> >> >>> the >>> >>> >> >>> following way: >>> >>> >> >>> Version 0 -> accept acks >1. I think we should keep the >>> >>> >> >>> existing >>> >>> >> >>> behavior too (i.e. not replace it with -1) to avoid surprising >>> >>> >> >>> clients, but I'm willing to hear other opinions. >>> >>> >> >>> Version 1 -> do not accept acks >1 and return an error. >>> >>> >> >>> Are we ok with the error I added in KAFKA-1697? We can use >>> >>> >> >>> something >>> >>> >> >>> less specific like InvalidRequestParameter. This error can be >>> >>> >> >>> reused >>> >>> >> >>> in the future and reduce the need to add errors, but will also >>> >>> >> >>> be >>> >>> less >>> >>> >> >>> clear to the client and its users. Maybe even add the error >>> >>> >> >>> message >>> >>> >> >>> string to the protocol in addition to the error code? (since >>> >>> >> >>> we are >>> >>> >> >>> bumping versions....) >>> >>> >> >>> >>> >>> >> >>> I think maintaining the old version throughout 0.8.X makes >>> >>> >> >>> sense. >>> >>> IMO >>> >>> >> >>> dropping it for 0.9 is feasible, but I'll let client owners >>> >>> >> >>> help >>> >>> make >>> >>> >> >>> that call. >>> >>> >> >>> >>> >>> >> >>> Am I missing anything? Should I start a KIP? It seems like a >>> >>> KIP-type >>> >>> >> >>> discussion :) >>> >>> >> >>> >>> >>> >> >>> Gwen >>> >>> >> >>> >>> >>> >> >>> >>> >>> >> >>> On Thu, Jan 15, 2015 at 2:31 PM, Ewen Cheslack-Postava >>> >>> >> >>> <e...@confluent.io> wrote: >>> >>> >> >>>> Gwen, >>> >>> >> >>>> >>> >>> >> >>>> I think the only option that wouldn't require a protocol >>> >>> >> >>>> version >>> >>> >> change is >>> >>> >> >>>> the one where acks > 1 is converted to acks = -1 since it's >>> >>> >> >>>> the >>> >>> only >>> >>> >> one >>> >>> >> >>>> that doesn't potentially break older clients. The protocol >>> >>> >> >>>> guide >>> >>> >> says that >>> >>> >> >>>> the expected upgrade path is servers first, then clients, so >>> >>> >> >>>> old >>> >>> >> clients, >>> >>> >> >>>> including non-java clients, that may be using acks > 1 should >>> >>> >> >>>> be >>> >>> >> able to >>> >>> >> >>>> work with a new broker version. >>> >>> >> >>>> >>> >>> >> >>>> It's more work, but I think dealing with the protocol change >>> >>> >> >>>> is the >>> >>> >> right >>> >>> >> >>>> thing to do since it eventually gets us to the behavior I >>> >>> >> >>>> think is >>> >>> >> better -- >>> >>> >> >>>> the broker should reject requests with invalid values. I >>> >>> >> >>>> think Joe >>> >>> >> and I >>> >>> >> >>>> were basically in agreement. In my mind the major piece >>> >>> >> >>>> missing >>> >>> from >>> >>> >> his >>> >>> >> >>>> description is how long we're going to maintain his "case 0" >>> >>> >> behavior. It's >>> >>> >> >>>> impractical to maintain old versions forever, but it sounds >>> >>> >> >>>> like >>> >>> >> there >>> >>> >> >>>> hasn't been a decision on how long to maintain them. Maybe >>> >>> >> >>>> that's >>> >>> >> another >>> >>> >> >>>> item to add to KIPs -- protocol versions and behavior need to >>> >>> >> >>>> be >>> >>> >> listed as >>> >>> >> >>>> deprecated and the earliest version in which they'll be >>> >>> >> >>>> removed >>> >>> >> should be >>> >>> >> >>>> specified so users can understand which versions are >>> >>> >> >>>> guaranteed to >>> >>> be >>> >>> >> >>>> compatible, even if they're using (well-written) non-java >>> >>> >> >>>> clients. >>> >>> >> >>>> >>> >>> >> >>>> -Ewen >>> >>> >> >>>> >>> >>> >> >>>> >>> >>> >> >>>>> On Thu, Jan 15, 2015 at 12:52 PM, Dana Powers < >>> >>> >> dana.pow...@gmail.com> wrote: >>> >>> >> >>>>> >>> >>> >> >>>>>> clients don't break on unknown errors >>> >>> >> >>>>> >>> >>> >> >>>>> maybe true for the official java clients, but I dont think >>> >>> >> >>>>> the >>> >>> >> assumption >>> >>> >> >>>>> holds true for community-maintained clients and users of >>> >>> >> >>>>> those >>> >>> >> clients. >>> >>> >> >>>>> kafka-python generally follows the fail-fast philosophy and >>> >>> >> >>>>> raises >>> >>> >> an >>> >>> >> >>>>> exception on any unrecognized error code in any server >>> >>> >> >>>>> response. >>> >>> >> in this >>> >>> >> >>>>> case, kafka-python allows users to set their own >>> >>> >> >>>>> required-acks >>> >>> >> policy when >>> >>> >> >>>>> creating a producer instance. It is possible that users of >>> >>> >> kafka-python >>> >>> >> >>>>> have deployed producer code that uses ack>1 -- perhaps in >>> >>> production >>> >>> >> >>>>> environments -- and for those users the new error code will >>> >>> >> >>>>> crash >>> >>> >> their >>> >>> >> >>>>> producer code. I would not be surprised if the same were >>> >>> >> >>>>> true of >>> >>> >> other >>> >>> >> >>>>> community clients. >>> >>> >> >>>>> >>> >>> >> >>>>> *one reason for the fail-fast approach is that there isn't >>> >>> >> >>>>> great >>> >>> >> >>>>> documentation on what errors to expect for each request / >>> >>> >> >>>>> response >>> >>> >> -- so >>> >>> >> >>>>> we >>> >>> >> >>>>> use failures to alert that some error case is not handled >>> >>> >> properly. and >>> >>> >> >>>>> because of that, introducing new error cases without bumping >>> >>> >> >>>>> the >>> >>> api >>> >>> >> >>>>> version is likely to cause those errors to get raised/thrown >>> >>> >> >>>>> all >>> >>> >> the way >>> >>> >> >>>>> back up to the user. of course we (client maintainers) can >>> >>> >> >>>>> fix >>> >>> the >>> >>> >> issues >>> >>> >> >>>>> in the client libraries and suggest users upgrade, but it's >>> >>> >> >>>>> not >>> >>> the >>> >>> >> ideal >>> >>> >> >>>>> situation. >>> >>> >> >>>>> >>> >>> >> >>>>> >>> >>> >> >>>>> long-winded way of saying: I agree w/ Joe. >>> >>> >> >>>>> >>> >>> >> >>>>> -Dana >>> >>> >> >>>>> >>> >>> >> >>>>> >>> >>> >> >>>>> On Thu, Jan 15, 2015 at 12:07 PM, Gwen Shapira < >>> >>> >> gshap...@cloudera.com> >>> >>> >> >>>>> wrote: >>> >>> >> >>>>> >>> >>> >> >>>>>> Is the protocol bump caused by the behavior change or the >>> >>> >> >>>>>> new >>> >>> error >>> >>> >> >>>>>> code? >>> >>> >> >>>>>> >>> >>> >> >>>>>> 1) IMO, error_codes are data, and clients can expect to >>> >>> >> >>>>>> receive >>> >>> >> errors >>> >>> >> >>>>>> that they don't understand (i.e. unknown errors). AFAIK, >>> >>> >> >>>>>> clients >>> >>> >> don't >>> >>> >> >>>>>> break on unknown errors, they are simple more challenging >>> >>> >> >>>>>> to >>> >>> >> debug. If >>> >>> >> >>>>>> we document the new behavior, then its definitely >>> >>> >> >>>>>> debuggable and >>> >>> >> >>>>>> fixable. >>> >>> >> >>>>>> >>> >>> >> >>>>>> 2) The behavior change is basically a deprecation - i.e. >>> >>> >> >>>>>> acks > 1 >>> >>> >> were >>> >>> >> >>>>>> never documented, and are not supported by Kafka clients >>> >>> >> >>>>>> starting >>> >>> >> with >>> >>> >> >>>>>> version 0.8.2. I'm not sure this requires a protocol bump >>> >>> >> >>>>>> either, >>> >>> >> >>>>>> although its a better case than new error codes. >>> >>> >> >>>>>> >>> >>> >> >>>>>> Thanks, >>> >>> >> >>>>>> Gwen >>> >>> >> >>>>>> >>> >>> >> >>>>>> On Thu, Jan 15, 2015 at 10:10 AM, Joe Stein < >>> >>> joe.st...@stealth.ly> >>> >>> >> >>>>>> wrote: >>> >>> >> >>>>>>> Looping in the mailing list that the client developers >>> >>> >> >>>>>>> live on >>> >>> >> because >>> >>> >> >>>>>> they >>> >>> >> >>>>>>> are all not on dev (though they should be if they want to >>> >>> >> >>>>>>> be >>> >>> >> helping >>> >>> >> >>>>>>> to >>> >>> >> >>>>>>> build the best client libraries they can). >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> I whole hardily believe that we need to not break existing >>> >>> >> >>>>>>> functionality >>> >>> >> >>>>>> of >>> >>> >> >>>>>>> the client protocol, ever. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> There are many reasons for this and we have other threads >>> >>> >> >>>>>>> on the >>> >>> >> >>>>>>> mailing >>> >>> >> >>>>>>> list where we are discussing that topic (no pun intended) >>> >>> >> >>>>>>> that I >>> >>> >> don't >>> >>> >> >>>>>> want >>> >>> >> >>>>>>> to re-hash here. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> If we change wire protocol functionality OR the binary >>> >>> >> >>>>>>> format >>> >>> >> (either) >>> >>> >> >>>>>>> we >>> >>> >> >>>>>>> must bump version AND treat version as a feature flag with >>> >>> >> backward >>> >>> >> >>>>>>> compatibility support until it is deprecated for some time >>> >>> >> >>>>>>> for >>> >>> >> folks >>> >>> >> >>>>>>> to >>> >>> >> >>>>>> deal >>> >>> >> >>>>>>> with it. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> match version = { >>> >>> >> >>>>>>> case 0: keepDoingWhatWeWereDoing() >>> >>> >> >>>>>>> case 1: doNewStuff() >>> >>> >> >>>>>>> case 2: doEvenMoreNewStuff() >>> >>> >> >>>>>>> } >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> has to be a practice we adopt imho ... I know feature >>> >>> >> >>>>>>> flags can >>> >>> be >>> >>> >> >>>>>> construed >>> >>> >> >>>>>>> as "messy code" but I am eager to hear another (better? >>> >>> >> different?) >>> >>> >> >>>>>> solution >>> >>> >> >>>>>>> to this. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> If we don't do a feature flag like this specifically with >>> >>> >> >>>>>>> this >>> >>> >> change >>> >>> >> >>>>>> then >>> >>> >> >>>>>>> what happens is that someone upgrades their brokers with a >>> >>> rolling >>> >>> >> >>>>>> restart >>> >>> >> >>>>>>> in 0.8.3 and every single one of their producer requests >>> >>> >> >>>>>>> start >>> >>> to >>> >>> >> fail >>> >>> >> >>>>>> and >>> >>> >> >>>>>>> they have a major production outage. eeeek!!!! >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> I do 100% agree that > 1 makes no sense and we *REALLY* >>> >>> >> >>>>>>> need >>> >>> >> people to >>> >>> >> >>>>>> start >>> >>> >> >>>>>>> using 0,1,-1 but we need to-do that in a way that is going >>> >>> >> >>>>>>> to >>> >>> >> work for >>> >>> >> >>>>>>> everyone. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> Old producers and consumers must keep working with new >>> >>> >> >>>>>>> brokers >>> >>> >> and if >>> >>> >> >>>>>>> we >>> >>> >> >>>>>> are >>> >>> >> >>>>>>> not going to support that then I am unclear what the use >>> >>> >> >>>>>>> of >>> >>> >> "version" >>> >>> >> >>>>>>> is >>> >>> >> >>>>>>> based on our original intentions of having it because of >>> >>> >> >>>>>>> the >>> >>> >> >>>>>>> 0.7=>-0.8. >>> >>> >> >>>>>> We >>> >>> >> >>>>>>> said no more breaking changes when we did that. >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> - Joe Stein >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> On Thu, Jan 15, 2015 at 12:38 PM, Ewen Cheslack-Postava < >>> >>> >> >>>>>> e...@confluent.io> >>> >>> >> >>>>>>> wrote: >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> Right, so this looks like it could create an issue >>> >>> >> >>>>>>>> similar to >>> >>> >> what's >>> >>> >> >>>>>>>> currently being discussed in >>> >>> >> >>>>>>>> https://issues.apache.org/jira/browse/KAFKA-1649 where >>> >>> >> >>>>>>>> users >>> >>> >> now get >>> >>> >> >>>>>>>> errors >>> >>> >> >>>>>>>> under conditions when they previously wouldn't. Old >>> >>> >> >>>>>>>> clients >>> >>> won't >>> >>> >> >>>>>>>> even >>> >>> >> >>>>>>>> know >>> >>> >> >>>>>>>> about the error code, so besides failing they won't even >>> >>> >> >>>>>>>> be >>> >>> able >>> >>> >> to >>> >>> >> >>>>>>>> log >>> >>> >> >>>>>>>> any >>> >>> >> >>>>>>>> meaningful error messages. >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> I think there are two options for compatibility: >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> 1. An alternative change is to remove the ack > 1 code, >>> >>> >> >>>>>>>> but >>> >>> >> silently >>> >>> >> >>>>>>>> "upgrade" requests with acks > 1 to acks = -1. This isn't >>> >>> >> >>>>>>>> the >>> >>> >> same as >>> >>> >> >>>>>>>> other >>> >>> >> >>>>>>>> changes to behavior since the interaction between the >>> >>> >> >>>>>>>> client >>> >>> and >>> >>> >> >>>>>>>> server >>> >>> >> >>>>>>>> remains the same, no error codes change, etc. The client >>> >>> >> >>>>>>>> might >>> >>> >> just >>> >>> >> >>>>>>>> see >>> >>> >> >>>>>>>> some increased latency since the message might need to be >>> >>> >> replicated >>> >>> >> >>>>>>>> to >>> >>> >> >>>>>>>> more brokers than they requested. >>> >>> >> >>>>>>>> 2. Split this into two patches, one that bumps the >>> >>> >> >>>>>>>> protocol >>> >>> >> version >>> >>> >> >>>>>>>> on >>> >>> >> >>>>>>>> that >>> >>> >> >>>>>>>> message to include the new error code but maintains both >>> >>> >> >>>>>>>> old >>> >>> (now >>> >>> >> >>>>>>>> deprecated) and new behavior, then a second that would be >>> >>> >> applied in >>> >>> >> >>>>>>>> a >>> >>> >> >>>>>>>> later release that removes the old protocol + code for >>> >>> >> >>>>>>>> handling >>> >>> >> acks >>> >>> >> >>>>>> 1. >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> 2 is probably the right thing to do. If we specify the >>> >>> >> >>>>>>>> release >>> >>> >> when >>> >>> >> >>>>>> we'll >>> >>> >> >>>>>>>> remove the deprecated protocol at the time of deprecation >>> >>> >> >>>>>>>> it >>> >>> >> makes >>> >>> >> >>>>>> things >>> >>> >> >>>>>>>> a >>> >>> >> >>>>>>>> lot easier for people writing non-java clients and could >>> >>> >> >>>>>>>> give >>> >>> >> users >>> >>> >> >>>>>> better >>> >>> >> >>>>>>>> predictability (e.g. if clients are at most 1 major >>> >>> >> >>>>>>>> release >>> >>> >> behind >>> >>> >> >>>>>>>> brokers, >>> >>> >> >>>>>>>> they'll remain compatible but possibly use deprecated >>> >>> features). >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> On Wed, Jan 14, 2015 at 3:51 PM, Gwen Shapira < >>> >>> >> gshap...@cloudera.com> >>> >>> >> >>>>>>>> wrote: >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>>> Hi Kafka Devs, >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> We are working on KAFKA-1697 - remove code related to >>> >>> >> >>>>>>>>> ack>1 on >>> >>> >> the >>> >>> >> >>>>>>>>> broker. Per Neha's suggestion, I'd like to give everyone >>> >>> >> >>>>>>>>> a >>> >>> >> heads up >>> >>> >> >>>>>>>>> on >>> >>> >> >>>>>>>>> what these changes mean. >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> Once this patch is included, any produce requests that >>> >>> >> >>>>>>>>> include >>> >>> >> >>>>>>>>> request.required.acks > 1 will result in an exception. >>> >>> >> >>>>>>>>> This >>> >>> >> will be >>> >>> >> >>>>>>>>> InvalidRequiredAcks in new versions (0.8.3 and up, I >>> >>> >> >>>>>>>>> assume) >>> >>> and >>> >>> >> >>>>>>>>> UnknownException in existing versions (sorry, but I >>> >>> >> >>>>>>>>> can't add >>> >>> >> error >>> >>> >> >>>>>>>>> codes retroactively). >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> This behavior is already enforced by 0.8.2 producers >>> >>> >> >>>>>>>>> (sync and >>> >>> >> >>>>>>>>> new), >>> >>> >> >>>>>>>>> but we expect impact on users with older producers that >>> >>> >> >>>>>>>>> relied >>> >>> >> on >>> >>> >> >>>>>>>>> acks >>> >>> >> >>>>>>>>>> 1 and external clients (i.e python, go, etc). >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> Users who relied on acks > 1 are expected to switch to >>> >>> >> >>>>>>>>> using >>> >>> >> acks = >>> >>> >> >>>>>>>>> -1 >>> >>> >> >>>>>>>>> and a min.isr parameter than matches their user case. >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> This change was discussed in the past in the context of >>> >>> >> KAFKA-1555 >>> >>> >> >>>>>>>>> (min.isr), but let us know if you have any questions or >>> >>> concerns >>> >>> >> >>>>>>>>> regarding this change. >>> >>> >> >>>>>>>>> >>> >>> >> >>>>>>>>> Gwen >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> >>> >>> >> >>>>>>>> -- >>> >>> >> >>>>>>>> Thanks, >>> >>> >> >>>>>>>> Ewen >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> -- >>> >>> >> >>>>>>> You received this message because you are subscribed to >>> >>> >> >>>>>>> the >>> >>> Google >>> >>> >> >>>>>>> Groups >>> >>> >> >>>>>>> "kafka-clients" group. >>> >>> >> >>>>>>> To unsubscribe from this group and stop receiving emails >>> >>> >> >>>>>>> from >>> >>> it, >>> >>> >> send >>> >>> >> >>>>>>> an >>> >>> >> >>>>>>> email to kafka-clients+unsubscr...@googlegroups.com. >>> >>> >> >>>>>>> To post to this group, send email to >>> >>> >> kafka-clie...@googlegroups.com. >>> >>> >> >>>>>>> Visit this group at >>> >>> http://groups.google.com/group/kafka-clients. >>> >>> >> >>>>>>> To view this discussion on the web visit >>> >>> >> >>>>>> >>> >>> >> >>>>>> >>> >>> >> >>> >>> >>> >>> https://groups.google.com/d/msgid/kafka-clients/CAA7ooCBtH2JjyQsArdx_%3DV25B4O1QJk0YvOu9U6kYt9sB4aqng%40mail.gmail.com >>> >>> >> >>>>>> . >>> >>> >> >>>>>>> >>> >>> >> >>>>>>> For more options, visit >>> >>> >> >>>>>>> https://groups.google.com/d/optout. >>> >>> >> >>>>>> >>> >>> >> >>>>>> -- >>> >>> >> >>>>>> You received this message because you are subscribed to the >>> >>> Google >>> >>> >> >>>>>> Groups >>> >>> >> >>>>>> "kafka-clients" group. >>> >>> >> >>>>>> To unsubscribe from this group and stop receiving emails >>> >>> >> >>>>>> from it, >>> >>> >> send >>> >>> >> >>>>>> an >>> >>> >> >>>>>> email to kafka-clients+unsubscr...@googlegroups.com. >>> >>> >> >>>>>> To post to this group, send email to >>> >>> >> kafka-clie...@googlegroups.com. >>> >>> >> >>>>>> Visit this group at >>> >>> >> >>>>>> http://groups.google.com/group/kafka-clients >>> >>> . >>> >>> >> >>>>>> To view this discussion on the web visit >>> >>> >> >>>>>> >>> >>> >> >>>>>> >>> >>> >> >>> >>> >>> >>> https://groups.google.com/d/msgid/kafka-clients/CAHBV8WeUebxi%2B%2BSbjz8E9Yf4u4hkcPJ80Xsj0XTKcTac%3D%2B613A%40mail.gmail.com >>> >>> >> >>>>>> . >>> >>> >> >>>>>> For more options, visit https://groups.google.com/d/optout. >>> >>> >> >>>> >>> >>> >> >>>> >>> >>> >> >>>> >>> >>> >> >>>> >>> >>> >> >>>> -- >>> >>> >> >>>> Thanks, >>> >>> >> >>>> Ewen >>> >>> >> >>> >>> > >>> >>> > >>> >>> >>> >>> >>> >>> -- >>> >>> Thanks, >>> >>> Ewen >>> >>> >>> >> >>> >> >>> >> >>> >> -- >>> >> Thanks, >>> >> Neha >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "kafka-clients" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to kafka-clients+unsubscr...@googlegroups.com. >> To post to this group, send email to kafka-clie...@googlegroups.com. >> Visit this group at http://groups.google.com/group/kafka-clients. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/kafka-clients/CAOeJiJh17CYq%3D-qgPu9rnArsPW%3D7RL9AAW_h%3DrrXx0%2BKhhKgNQ%40mail.gmail.com. >> >> For more options, visit https://groups.google.com/d/optout. > >
