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Re: Kafka wiki Documentation conventions - looking for feedback
Thanks. I also updated your producer example to reflect a recent config
change (broker.list => metadata.broker.list).

Jun
On Mon, Apr 29, 2013 at 11:19 AM, Chris Curtin <[EMAIL PROTECTED]>wrote:

> Thanks, I missed that the addition of consumers can cause a re-balance.
> Thought it was only on Leader changes.
>
> I've updated the wording in the example.
>
> I'll pull down the beta and test my application then change the names on
> the properties.
>
> Thanks,
>
> Chris
>
>
> On Mon, Apr 29, 2013 at 11:58 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
>
> > Basically, every time a consumer joins a group, every consumer in the
> > groups gets a ZK notification and each of them tries to own a subset of
> the
> > total number of partitions. A given partition is only assigned to one of
> > the consumers in the same group. Once the ownership is determined, each
> > consumer consumes messages coming from its partitions and manages the
> > offset of those partitions. Since at any given point of time, a partition
> > is only owned by one consumer, there won't be conflicts on updating the
> > offsets. More details are described in the "consumer rebalancing
> algorithm"
> > section of http://kafka.apache.org/07/design.html
> >
> > Thanks,
> >
> > Jun
> >
> >
> > On Mon, Apr 29, 2013 at 8:16 AM, Chris Curtin <[EMAIL PROTECTED]
> > >wrote:
> >
> > > Jun, can you explain this a little better? I thought when using
> Consumer
> > > Groups that on startup Kafka connects to ZooKeeper and finds the last
> > read
> > > offset for every partition in the topic being requested for the group.
> > That
> > > is then the starting point for the consumer threads.
> > >
> > > If a second process starts while the first one is running with the same
> > > Consumer Group, won't the second one read the last offsets consumed by
> > the
> > > already running process and start processing from there? Then as the
> > first
> > > process syncs consumed offsets, won't the 2nd process's next update
> > > overwrite them?
> > >
> > > Thanks,
> > >
> > > Chris
> > >
> > >
> > >
> > >
> > > On Mon, Apr 29, 2013 at 11:03 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
> > >
> > > > Chris,
> > > >
> > > > Thanks for the writeup. Looks great overall. A couple of comments.
> > > >
> > > > 1. At the beginning, it sounds like that one can't run multiple
> > processes
> > > > of consumers in the same group. This is actually not true. We can
> > create
> > > > multiple instances of consumers for the same group in the same JVM or
> > > > different JVMs. The consumers will auto-balance among themselves.
> > > >
> > > > 2. We have changed the name of some config properties.
> > > > auto.commit.interval.ms is correct. However, zk.connect,
> > > > zk.session.timeout.ms and zk.sync.time.ms are changed to
> > > > zookeeper.connect,
> > > > zookeeper.session.timeout.ms, and zookeeper.sync.time.ms,
> > respectively.
> > > >
> > > > I will add a link to your wiki in our website.
> > > >
> > > > Thanks again.
> > > >
> > > > Jun
> > > >
> > > >
> > > > On Mon, Apr 29, 2013 at 5:54 AM, Chris Curtin <
> [EMAIL PROTECTED]
> > > > >wrote:
> > > >
> > > > > Hi Jun,
> > > > >
> > > > > I finished and published it this morning:
> > > > >
> > > > >
> > >
> https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example
> > > > >
> > > > > One question: when documenting the ConsumerConfig parameters I
> > couldn't
> > > > > find a description for the 'auto.commit.interval.ms' setting. I
> > found
> > > > one
> > > > > for 'autocommit.interval.ms' (no '.' between auto and commit) in
> the
> > > > > Google
> > > > > Cache only. Which spelling is it? Also is my description of it
> > correct?
> > > > >
> > > > > I'll take a look at custom encoders later this week. Today and
> > Tuesday
> > > > are
> > > > > going to be pretty busy.
> > > > >
> > > > > Please let me know if there are changes needed to the High Level
> > > Consumer
> > > > > page.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Chris