kafka-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Chris Curtin <curtin.ch...@gmail.com>
Subject Re: Kafka wiki Documentation conventions - looking for feedback
Date Wed, 01 May 2013 19:33:35 GMT
Hi Jun

I've added #1 and #2.

I'll need to think about where to put #3, maybe even adding a 'tips and
tricks' section?

I've not had to do any encoder/decoders. Can anyone else offer some example
code I can incorporate into an example?

Thanks,

Chris


On Wed, May 1, 2013 at 11:45 AM, Jun Rao <junrao@gmail.com> wrote:

> Chris,
>
> Thanks. This is very helpful. I linked your wiki pages to our website. A
> few more comments:
>
> 1. Producer: The details of the meaning of request.required.acks are
> described in http://kafka.apache.org/08/configuration.html. It would be
> great if you can add a link to the description in your wiki.
>
> 2. High level consumer: Could you add the proper way of stopping the
> consumer? One just need to call consumer.shutdown(). After this is called,
> hasNext() call in the Kafka stream iterator will return false.
>
> 3. SimpleConsumer: We have the following api that returns the offset of the
> last message exposed to the consumer. The difference btw high watermark and
> the offset of the last consumed message tells you how many messages the
> consumer is behind the broker.
>   highWatermark(topic: String, partition: Int)
>
> Finally, it would be great if you can extend the wiki with customized
> encoder (Producer) and decoder (Consumer) at some point.
> Thanks,
>
> Jun
>
>
> On Wed, May 1, 2013 at 6:44 AM, Chris Curtin <curtin.chris@gmail.com>
> wrote:
>
> > I've tested my examples with the new (4/30) release and they work, so
> I've
> > updated the documentation.
> >
> > Thanks,
> >
> > Chris
> >
> >
> > On Mon, Apr 29, 2013 at 6:18 PM, Jun Rao <junrao@gmail.com> wrote:
> >
> > > 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 <curtin.chris@gmail.com
> > > >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 <junrao@gmail.com> 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 <
> > curtin.chris@gmail.com
> > > > > >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 <junrao@gmail.com>
> > 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 <
> > > > curtin.chris@gmail.com
> > > > > > > >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
> > > > > > > >
> > > > > > > >
> > > > > > > > On Mon, Apr 29, 2013 at 12:50 AM, Jun Rao <junrao@gmail.com>
> > > > wrote:
> > > > > > > >
> > > > > > > > > Chris,
> > > > > > > > >
> > > > > > > > > Any update of the high level consumer example?
> > > > > > > > >
> > > > > > > > > Also, in the Producer example, it would be useful
to
> describe
> > > how
> > > > > to
> > > > > > > > write
> > > > > > > > > a customized encoder. One subtle thing is that
the encoder
> > > needs
> > > > a
> > > > > > > > > constructor that takes a a single VerifiableProperties
> > > argument (
> > > > > > > > > https://issues.apache.org/jira/browse/KAFKA-869).
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > >
> > > > > > > > > Jun
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message