Throwing a +1 on "Allow the consumer to reset its offset to some arbitrary value, and then write that offset into ZK".
We're currently running into a scenario where we would like to have 100% reliability, and we're losing a few messages when a connection is broken, but there were still a few messages in the OS TCP buffers. So, we're planning on shifting the ZK offset by a few seconds "back in time" if we detect a broker has gone down, to make sure all the messages will be actually delivered to the end consumer when that broker comes back up, even if there's a small amount of overlapping messages. Thanks, Marcos On Jun 14, 2012, at 2:39 PM, Evan Chan wrote: > I would like to throw in a couple use cases: > > > - Allow the new consumer to reset its offset to either the current > largest or smallest. This would be a great way to restart a process that > has fallen behind. The only way I know how to do this today, with the > high-level consumer, is to delete the ZK nodes manually and restart the > consumer. > - Allow the consumer to reset its offset to some arbitrary value, and > then write that offset into ZK. Kind of like the first case, but would > make rewinding/replays much easier. > > Modularity (the ability to layer the ZK infrastructure on top of the simple > interface) would be great. > > thanks, > Evan > > > On Tue, Jun 12, 2012 at 9:59 AM, Jay Kreps <jay.kr...@gmail.com> wrote: > >> This is a great summary Neha. It would be good to get people's feedback on >> this since we don't want to keep breaking api and >> protocol compatibility here, so the hope is to really get it right this >> time now that we have really seen all the use cases and live with the >> output for a while. I think the consumer design is a pretty hard protocol >> and API design problem, so its fun to think about. >> >> If I were to summarize Neha's requirements list, I think there are three >> high-level goals: >> >> 1. Simplify the consumer protocol to enable ease of development of >> consumer clients in other languages >> 2. Try to replace the "simple consumer" and "high level consumer" with a >> single, general interface that has all the advantages of both. >> 3. Support a bunch of use cases that either we didn't think of, or that >> weren't possible in the partitioning model of the pre-0.8 code base. >> >> -Jay >> >> >> On Mon, Jun 11, 2012 at 4:52 PM, Neha Narkhede <neha.narkh...@gmail.com >>> wrote: >> >>> Hi, >>> >>> Over the past few months, we've received quite a lot of feedback on the >>> consumer side features and design. Some of them are improvements to the >>> current consumer design and some are simply new feature/API requests. I >>> have attempted to write up the requirements that I've heard on this wiki >> - >>> >> https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Client+Re-Design >>> >>> This would involve some significant changes to the consumer APIs, so we >>> would like to collect feedback on the proposal from our community. Since >>> the list of changes is not small, we would like to understand if some >>> features are preferred over others, and more importantly, if some >> features >>> are not required at all. >>> >>> Since some part of this proposal is experimental and the consumer side >>> changes are non-trivial, we would like this initiative to not interfere >>> with the forthcoming replication release. However, it will be good to >> have >>> people from the community give this some thought and help out with the >>> JIRAs if interested. One way of managing this project could be creating a >>> separate branch from the kafka trunk and continue development on it. Once >>> it is ready and in good shape, we can think about cutting another release >>> (after 0.8) for the releasing the new consumer API. Do people have >>> preferences/concerns regarding creating a separate branch for this >> project >>> ? >>> >>> Please feel free to start a discussion on this JIRA - >>> https://issues.apache.org/jira/browse/KAFKA-364 >>> >>> Thanks, >>> >>> Neha >>> >> > > > > -- > -- > *Evan Chan* > Senior Software Engineer | > e...@ooyala.com | (650) 996-4600 > www.ooyala.com | blog <http://www.ooyala.com/blog> | > @ooyala<http://www.twitter.com/ooyala>
