But why? What is reason for triggering a rebalance if none of the topics of
a consumers are affected? Is there some reason  for triggering a rebalance
irrespective of the consumers topics getting affected ?

On 11 May 2015 at 11:06, Manikumar Reddy <ku...@nmsworks.co.in> wrote:

> If both C1,C2 belongs to same consumer group, then the re-balance will be
> triggered.
> A consumer subscribes to event changes of the consumer id registry within
> its group.
>
> On Mon, May 11, 2015 at 10:55 AM, dinesh kumar <dinesh...@gmail.com>
> wrote:
>
> > Hi,
> > I am looking at the code of
> kafka.consumer.ZookeeperConsumerConnector.scala
> > (link here
> > <
> >
> https://github.com/apache/kafka/blob/0.8.2/core/src/main/scala/kafka/consumer/ZookeeperConsumerConnector.scala
> > >)
> > and I see that all ids registered to a particular group ids are
> registered
> > to  the path /consumers/[group_id]/ids in zookeeper. the ids contain the
> > consumer_id -> topics mapping.
> >
> > A watcher is registered in zookeeper that is triggered when there is a
> > change to /consumers/[group_id]/ids. This watcher event is handled by the
> > class ZKRebalancerListener. This class calls a synced rebalance whenever
> a
> > watcher event is received.
> >
> > So here is my question.
> > 1. Lets consider a scenario where there a two topics T1 and T2 and two
> > consumers C1 and C2. C1 consumes only from T1 and C2 only from T2. Say if
> > C2 dies for some reason as explained before, C1 will get a watcher event
> > from zookeeper and a synced rebalance will be triggered. Why does C2
> dying
> > which has absolutely nothing with C1 (there is no intersection of topics
> > between C1 and C2) should trigger a rebalance event in C1. Is there some
> > condition where this is necessary that I am missing?
> >
> > Thanks,
> > Dinesh
> >
>

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