Thanks Neha for the clarification. I have created a new entry in FAQ for this question:
https://cwiki.apache.org/confluence/display/KAFKA/FAQ#FAQ-CanIpredicttheresultsoftheconsumerrebabalance%3F Dennis, please let me know if this does not fully answer your question. Guozhang On Thu, Aug 22, 2013 at 9:29 AM, Neha Narkhede <neha.narkh...@gmail.com>wrote: > We range partition a sorted list of topic-partitions over a sorted list of > consumer instances. This makes the rebalancing algorithm deterministic. As > soon as you bring up the 2nd consumer instance, if its position in the > sorted list is before the position of the 1st consumer client, it will end > up owning the partition. > > Thanks, > Neha > > > On Thu, Aug 22, 2013 at 8:53 AM, Dennis Haller <dhal...@talemetry.com > >wrote: > > > I have a situation where two high level consumers are being created to > > consume a single topic. There is only one partition for the topic, so I > > understand that only one Consumer will end up owning the topic and > > receiving messages. The two consumers are created from two servers in a > > redundant master - slave configuration, and it is our intention that the > > servers should start in the same configuration predictably, with all the > > Consumers active on the master server. > > > > However, we find after both Consumers have been created that sometimes > the > > first Consumer client succeeds in owning the topic and sometimes it is > the > > second. I first thought that the first Consumer client to register with > > the topic would be retained even if subsequent Consumers also register > for > > the topic, but I see sometimes the second Consumer client succeeds in > > replacing the first Consumer. > > > > The logs show a rebalancing algorithm working after each Consumer is > > registered. > > > > In this case, where there is only one topic-partition, is it possible to > > predict what Consumer client will own the topic? How is that rebalancing > > done? > > > > Thanks > > Dennis > > > -- -- Guozhang
