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Kafka >> mail # user >> Kafka wiki Documentation conventions - looking for feedback


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Chris Curtin 2013-03-25, 12:03
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Chris Curtin 2013-03-29, 15:28
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Jun Rao 2013-04-22, 16:27
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Chris Curtin 2013-04-22, 17:41
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Jun Rao 2013-04-22, 22:12
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Jun Rao 2013-04-29, 04:51
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Chris Curtin 2013-04-29, 12:55
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Jun Rao 2013-04-29, 15:03
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Chris Curtin 2013-04-29, 15:17
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Jun Rao 2013-04-29, 15:58
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Chris Curtin 2013-04-29, 18:19
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Jun Rao 2013-04-29, 22:18
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Chris Curtin 2013-05-01, 13:56
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Re: Kafka wiki Documentation conventions - looking for feedback
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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[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

 
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Chris Curtin 2013-05-01, 19:34
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Jun Rao 2013-05-01, 21:37
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Jun Rao 2013-04-24, 16:26
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Chris Curtin 2013-04-24, 18:12
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Jun Rao 2013-04-25, 04:08