Sure! Just created the voting thread :)
On 2/24/15, 4:44 PM, "Jay Kreps" <j...@confluent.io> wrote:
>Hey Jiangjie,
>
>Let's do an official vote so that we know what we are voting on and we are
>crisp on what the outcome was. This thread is very long :-
>
>-Jay
>
>On Tue, Feb 24, 2015 at 2:53 PM, Jiangjie Qin <j...@linkedin.com.invalid>
>wrote:
>
>> I updated the KIP page based on the discussion we had.
>>
>> Should I launch another vote or we can think of this mail thread has
>> already included a vote?
>>
>> Jiangjie (Becket) Qin
>>
>> On 2/11/15, 5:15 PM, "Neha Nakhede" <n...@confluent.io> wrote:
>>
>> >Thanks for the explanation, Joel! Would love to see the results of the
>> >throughput experiment and I'm a +1 on everything else, ncluding the
>> >rebalance callback and record handler.
>> >
>> >-Neha
>> >
>> >On Wed, Feb 11, 2015 at 1:13 PM Jay Kreps <jay.kr...@gmail.com> wrote:
>> >
>> >> Cool, I agree with all that.
>> >>
>> >> I agree about the need for a rebalancing callback.
>> >>
>> >> Totally agree about record handler.
>> >>
>> >> It would be great to see if a prototype of this is workable.
>> >>
>> >> Thanks guys!
>> >>
>> >> -Jay
>> >>
>> >> On Wed, Feb 11, 2015 at 12:36 PM, Joel Koshy <jjkosh...@gmail.com>
>> >>wrote:
>> >>
>> >> > Hey Jay,
>> >> >
>> >> > Guozhang, Becket and I got together to discuss this and we think:
>> >> >
>> >> > - It seems that your proposal based on the new consumr and flush
>>call
>> >> > should work.
>> >> > - We would likely need to call the poll with a timeout that matches
>> >> > the offset commit interval in order to deal with low volume
>> >> > mirroring pipelines.
>> >> > - We will still need a rebalance callback to reduce duplicates -
>>the
>> >> > rebalance callback would need to flush and commit offsets.
>> >> > - The only remaining question is if the overall throughput is
>> >> > sufficient. I think someone at LinkedIn (I don't remember who)
>>did
>> >> > some experiments with data channel size == 1 and ran into issues.
>> >> > That was not thoroughly investigated though.
>> >> > - The addition of flush may actually make this solution viable for
>>the
>> >> > current mirror-maker (wih the old consumer). We can prototype
>>that
>> >> > offline and if it works out well we can redo KAFKA-1650 (i.e.,
>> >> > refactor the current mirror maker). The flush call and the new
>> >> > consumer didn't exist at the time we did KAFKA-1650 so this did
>>not
>> >> > occur to us.
>> >> > - We think the RecordHandler is still a useful small addition for
>>the
>> >> > use-cases mentioned earlier in this thread.
>> >> >
>> >> > Thanks,
>> >> >
>> >> > Joel
>> >> >
>> >> > On Wed, Feb 11, 2015 at 09:05:39AM -0800, Jay Kreps wrote:
>> >> > > Guozhang, I agree with 1-3, I do think what I was proposing was
>> >>simpler
>> >> > but
>> >> > > perhaps there re gaps in that?
>> >> > >
>> >> > > Hey Joel--Here was a sketch of what I was proposing. I do think
>>this
>> >> > get's
>> >> > > rid of manual offset tracking, especially doing so across threads
>> >>with
>> >> > > dedicated commit threads, which I think is prety complex.
>> >> > >
>> >> > > while(true) {
>> >> > > val recs = consumer.poll(Long.MaxValue);
>> >> > > for (rec <- recs)
>> >> > > producer.send(rec, logErrorCallback)
>> >> > > if(System.currentTimeMillis - lastCommit > commitInterval) {
>> >> > > producer.flush()
>> >> > > consumer.commit()
>> >> > > lastCommit = System.currentTimeMillis
>> >> > > }
>> >> > > }
>> >> > >
>> >> > > (See the previous email for details). I think the question is: is
>> >>there
>> >> > any
>> >> > > reason--performance, correctness, etc--that this won't work?
>> >>Basically
>> >> I
>> >> > > think you guys have thought about this more so I may be missing
> >> > something.
>> >> > > If so let's flag it while we still have leeway on the consumer.
>> >> > >
>> >> > > If we think that will work, well I do think it is conceptually a
>>lot
>> >> > > simpler than the current code, though I suppose one could
>>disagree
>> >>on
>> >> > that.
>> >> > >
>> >> > > -Jay
>> >> > >
>> >> > > On Wed, Feb 11, 2015 at 5:53 AM, Joel Koshy <jjkosh...@gmail.com>
>> >> wrote:
>> >> > >
>> >> > > > Hi Jay,
>> >> > > >
>> >> > > > > The data channels are actually a big part of the complexity
>>of
>> >>the
>> >> > zero
>> >> > > > > data loss design, though, right? Because then you need some
>> >>reverse
>> >> > > > channel
>> >> > > > > to flo the acks back to the consumer based on where you are
>> >>versus
>> >> > just
>> >> > > > > acking what you have read and written (as in the code
>>snippet I
>> >>put
>> >> > up).
>> >> > > >
>> >> > > > I'm not sure if we are on the same page. Even if the data
>>channel
>> >>was
>> >> > > > not there the current handling for zero data loss would remain
>> >>very
>> >> > > > similar - you would need to maintain lists of unacked source
>> >>offsets.
>> >> > > > I'm wondering if the KIP needs more detail on how it is
>>currently
>> >> > > > implemented; or are suggesting a different approach (in which
>> >>case I
>> >> > > > have not fully understood). I'm not sure what you mean by
>>flowing
>> >> acks
>> >> > > > back to the consumer - the MM commits offsets after the
>>producer
>> >>ack
>> >> > > > has been received. There is some additional complexity
>>introduced
>> >>in
>> >> > > > reducing duplicates on a rebalance - this is actually optional
>> >>(since
>> >> > > > duplicates are currently a given). The reason that was done
>> >>anyway is
>> >> > > > that with the auto-commit turned off duplicates are almost
>> >>guaranteed
>> >> > > > on a rebalance.
>> >> > > >
>> >> > > > > I think the point that Neha and I were trying to make was
>>that
>> >>the
>> >> > > > > motivation to embed stuff into MM kind of is related to how
>> >> complex a
>> >> > > > > simple "consume and produce" with good throughput will be. If
>> >>it is
>> >> > > > simple
>> >> > > > > to write such a thing in a few lines, the pain of embedding a
>> >>bunch
>> >> > of
>> >> > > > > stuff won't be worth it, if it has to be as complex as the
>> >>current
>> >> mm
>> >> > > > then
>> >> > > > > of course we will need all kinds of plug ins because no one
>> >>will be
>> >> > able
>> >> > > > to
>> >> > > > > write such a thing. I don't have a huge concern with a simple
>> >> plug-in
>> >> > > > but I
>> >> > > > > think if it turns into something more complex with filtering
>>and
>> >> > > > > aggregation or whatever we really need to stop and think a
>>bit
>> >> about
>> >> > the
> >> > > > > design.
>> >> > > >
>> >> > > > I agree - I don't think there is a use-case for any comple
>> >>plug-in.
>> >> > > > It is pretty much what Becket has described currently for the
>> >>message
>> >> > > > handler - i.e., take an incoming record and return a list of
>> >>outgoing
>> >> > > > records (which could be empty if you filter).
>> >> > > >
>> >> > > > So here is my take on the MM:
>> >> > > > - Bare bones: simple consumer - producer pairs (0.7 style).
>>This
>> >>is
>> >> > > > ideal, but does not handle no data los
>> >> > > > - Above plus support no data loss. This actually adds quite a
>>bit
>> >>of
>> >> > > > complexity.
>> >> > > > - Above plus the message handler. This is a trivial addition I
>> >>think
>> >> > > > that makes the MM usable in a few other mirroring-like
>> >> applications.
>> >> > > >
>> >> > > > Joel
>> >> > > >
>> >> > > > > On Tue, Feb 10, 2015 at 12:31 PM, Joel Koshy
>> >><jjkosh...@gmail.com>
>> >> > > > wrote:
>> >> > > > >
>> >> > > > > >
>> >> > > > > >
>> >> > > > > > On Tue, Feb 10, 2015 at 12:13:46PM -0800, Neha Narkhede
>>wrote:
>> >> > > > > > > I think all of us agree that we want to design
>>MirrorMaker
>> >>for
>> >> 0
>> >> > data
>> >> > > > > > loss.
>> >> > > > > > > With the absence of the data channel, 0 data loss will be
>> >>much
>> >> > > > simpler to
>> >> > > > > > > implement.
>> >> > > > > >
>> >> > > > > > The data channel is irrelevant to the implementation of
>>zero
>> >>data
>> >> > > > > > loss. The complexity in the implementation of no data loss
>> >>that
>> >> you
>> >> > > > > > are seeing in mirror-maker affects all consume-then-produce
>> >> > patterns
>> >> > > > > > whether or not there is a data channel. You still need to
>> >> > maintain a
>> >> > > > > > list of unacked offsets. What I meant earlier is that we
>>can
>> >> > > > > > brainstorm completely different approaches to supporting no
>> >>data
>> >> > loss,
>> >> > > > > > but the current implementation is the only solution we are
>> >>aware
>> >> > of.
>> >> > > > > >
>> >> > > > > > >
>> >> > > > > > > My arguments for adding a message handler are that:
>> >> > > > > > > > 1. It is more efficient to do something in common for
>>all
>> >>the
>> >> > > > clients
>> >> > > > > > in
>> >> > > > > > > > pipeline than letting each client do the same thing for
>> >>many
>> >> > > > times. And
>> >> > > > > > > > there are concrete use cases for the message handler
>> >>already.
>> >> > > > > > > >
>> >> > > > > > >
>> >> > > > > > > What are the concrete use cases?
>> >> > > > > >
>> >> > > > > > I think Becket already described a couple of use cases
>> >>earlier in
>> >> > the
>> >> > > > > > thread.
>> >> > > > > >
>> >> > > > > > <quote>
>> >> > > > > >
>> >> > > > > > 1. Format conversion. We have a use case where clients of
>> >>source
>> >> > > > > > cluster
>> >> > > > > > use an internal schema and clients of target cluster use a
>> >> > different
>> >> > > > > > public schema.
>> >> > > > > > 2. Message filtering: For the messages published to source
>> >> cluster,
>> >> > > > > > there
>> >> > > > > > are some messages private to source cluster clients and
>>should
>> >> not
>> >> > > > > > exposed
>> >> > > > > > to target cluster clients. It would be difficult to publish
>> >>those
>> >> > > > > > messages
>> >> > > > > > into different partitions because they need to be ordered.
>> >> > > > > > I agree that we can always filter/convert messages after
>>they
>> >>are
>> >> > > > > > copied
>> >> > > > > > to the target cluster, but that costs network bandwidth
>> >> > unnecessarily,
>> >> > > > > > especially if that is a cross colo mirror. With the
>>handler,
>> >>we
>> >> can
>> >> > > > > > co-locate the mirror maker with source cluster and save
>>that
>> >> cost.
>> >> > > > > > Also,
>> >> > > > > > imagine there are many downstream consumers consuming from
>>the
>> >> > target
>> >> > > > > > cluster, filtering/reformatting the messages before the
>> >>messages
>> >> > reach
>> >> > > > > > the
>> >> > > > > > target cluster is much more efficient than having each of
>>the
>> >> > > > > > consumers do
>> >> > > > > > this individually on their own.
>> >> > > > > >
>> >> > > > > > </quote>
>> >> > > > > >
>> >> > > > > > >
>> >> > > > > > > Also the KIP still refers to the data channel in a few
>> >>places
>> >> > > > (Motivation
>> >> > > > > > > and "On consumer rebalance" sections). Can you update the
>> >>wiki
>> >> > so it
>> >> > > > is
>> >> > > > > > > easier to review the new design, especially the data loss
>> >>part.
>> >> > > > > > >
>> >> > > > > > >
>> >> > > > > > > On Tue, Feb 10, 2015 at 10:36 AM, Joel Koshy <
>> >> > jjkosh...@gmail.com>
>> >> > > > > > wrote:
>> >> > > > > > >
>> >> > > > > > > > I think the message handler adds little to no
>>complexity
>> >>to
>> >> the
>> >> > > > mirror
>> >> > > > > > > > maker. Jay/Neha, the MM became scary due to the
>> >> rearchitecture
>> >> > we
>> >> > > > did
>> >> > > > > > > > for 0.8 due to performance issues compared with 0.7 -
>>we
>> >> should
>> >> > > > remove
>> >> > > > > > > > the data channel if it can match the current
>>throughput. I
>> >> > agree
>> >> > > > it is
>> >> > > > > > > > worth prototyping and testing that so the MM
>>architecture
>> >>is
>> >> > > > > > > > simplified.
>> >> > > > > > > >
>> >> > > > > > > > The MM became a little scarier in KAFKA-1650 in order
>>to
>> >> > support no
>> >> > > > > > > > data loss. I think the implementation for no data loss
>> >>will
>> >> > remain
>> >> > > > > > > > about the same even in the new model (even without the
>> >>data
>> >> > > > channel) -
>> >> > > > > > > > we can probably brainstorm more if there is a
>> >>better/simpler
>> >> > way
>> >> > > > to do
>> >> > > > > > > > it (maybe there is in the absence of the data channel)
>> >>but at
>> >> > the
>> >> > > > time
>> >> > > > > > > > it was the best we (i.e., Becket, myself, Jun and
>>Guozhang
>> >> who
>> >> > > > > > > > participated on the review) could come up with.
>> >> > > > > > > >
>> >> > > > > > > > So I'm definitely +1 on whatever it takes to support no
>> >>data
>> >> > loss.
>> >> > > > I
>> >> > > > > > > > think most people would want that out of the box.
>> >> > > > > > > >
>> >> > > > > > > > As for the message handler, as Becket wrote and I agree
>> >>with,
>> >> > it is
>> >> > > > > > > > really a trivial addition that would benefit (perhaps
>>not
>> >> most,
>> >> > > > but at
>> >> > > > > > > > least some). So I'm personally +1 on that as well. That
>> >>said,
>> >> > I'm
>> >> > > > also
>> >> > > > > > > > okay with it not being there. I think the MM is fairly
>> >> > stand-alone
>> >> > > > and
>> >> > > > > > > > simple enough that it is entirely reasonable and
>> >>absolutely
>> >> > > > feasible
>> >> > > > > > > > for companies to fork/re-implement the mirror maker for
>> >>their
>> >> > own
>> >> > > > > > > > needs.
>> >> > > > > > > >
>> >> > > > > > > > So in summary, I'm +1 on the KIP.
>> >> > > > > > > >
>> >> > > > > > > > Thanks,
>> >> > > > > > > >
>> >> > > > > > > > Joel
>> >> > > > > > > >
>> >> > > > > > > > On Mon, Feb 09, 2015 at 09:19:57PM +0000, Jiangjie Qin
>> >>wrote:
>> >> > > > > > > > > I just updated the KIP page and incorporated Jay and
>> >>Neha’s
>> >> > > > > > suggestion.
>> >> > > > > > > > As
>> >> > > > > > > > > a brief summary of where we are:
>> >> > > > > > > > >
>> >> > > > > > > > > Consensus reached:
>> >> > > > > > > > > Have N independent mirror maker threads each has
>>their
>> >>own
>> >> > > > consumers
>> >> > > > > > but
>> >> > > > > > > > > share a producer. The mirror maker threads will be
>> >> > responsible
>> >> > > > for
>> >> > > > > > > > > decompression, compression and offset commit. No data
>> >> > channel and
>> >> > > > > > > > separate
>> >> > > > > > > > > offset commit thread is needed. Consumer rebalance
>> >>callback
>> >> > will
>> >> > > > be
>> >> > > > > > used
>> >> > > > > > > > > to avoid duplicates on rebalance.
>> >> > > > > > > > >
>> >> > > > > > > > > Still under discussion:
>> >> > > > > > > > > Whether message handler is needed.
>> >> > > > > > > > >
>> >> > > > > > > > > My arguments for adding a message handler are that:
>> >> > > > > > > > > 1. It is more efficient to do something in common for
>> >>all
>> >> the
>> >> > > > > > clients in
>> >> > > > > > > > > pipeline than letting each client do the same thing
>>for
>> >> many
>> >> > > > times.
>> >> > > > > > And
>> >> > > > > > > > > there are concrete use cases for the message handler
>> >> already.
>> >> > > > > > > > > 2. It is not a big complicated add-on to mirror
>>maker.
>> >> > > > > > > > > 3. Without a message handler, for customers needs it,
>> >>they
>> >> > have
>> >> > > > to
>> >> > > > > > > > > re-implement all the logics of mirror maker by
>> >>themselves
>> >> > just in
>> >> > > > > > order
>> >> > > > > > > > to
>> >> > > > > > > > > add this handling in pipeline.
>> >> > > > > > > > >
>> >> > > > > > > > > Any thoughts?
>> >> > > > > > > > >
>> >> > > > > > > > > Thanks.
>> >> > > > > > > > >
>> >> > > > > > > > > ―Jiangjie (Becket) Qin
>> >> > > > > > > > >
>> >> > > > > > > > > On 2/8/15, 6:35 PM, "Jiangjie Qin"
>><j...@linkedin.com>
>> >> > wrote:
>> >> > > > > > > > >
>> >> > > > > > > > > >Hi Jay, thanks a lot for the comments.
>> >> > > > > > > > > >I think this solution is better. We probably don’t
>>need
>> >> data
>> >> > > > channel
>> >> > > > > > > > > >anymore. It can be replaced with a list of producer
>>if
>> >>we
>> >> > need
>> >> > > > more
>> >> > > > > > > > sender
>> >> > > > > > > > > >thread.
>> >> > > > > > > > > >I’ll update the KIP page.
>> >> > > > > > > > > >
>> >> > > > > > > > > >The reasoning about message handler is mainly for
>> >> efficiency
>> >> > > > > > purpose.
>> >> > > > > > > > I’m
>> >> > > > > > > > > >thinking that if something can be done in pipeline
>>for
>> >>all
>> >> > the
>> >> > > > > > clients
>> >> > > > > > > > > >such as filtering/reformatting, it is probably
>>better
>> >>to
>> >> do
>> >> > it
>> >> > > > in
>> >> > > > > > the
>> >> > > > > > > > > >pipeline than asking 100 clients do the same thing
>>for
>> >>100
>> >> > > > times.
>> >> > > > > > > > > >
>> >> > > > > > > > > >―Jiangjie (Becket) Qin
>> >> > > > > > > > > >
>> >> > > > > > > > > >
>> >> > > > > > > > > >On 2/8/15, 4:59 PM, "Jay Kreps"
>><jay.kr...@gmail.com>
>> >> > wrote:
>> >> > > > > > > > > >
>> >> > > > > > > > > >>Yeah, I second Neha's comments. The current mm code
>> >>has
>> >> > taken
>> >> > > > > > something
>> >> > > > > > > > > >>pretty simple and made it pretty scary with
>>callbacks
>> >>and
>> >> > > > > > wait/notify
>> >> > > > > > > > > >>stuff. Do we believe this works? I can't tell by
>> >>looking
>> >> > at it
>> >> > > > > > which is
>> >> > > > > > > > > >>kind of bad for something important like this. I
>>don't
>> >> mean
>> >> > > > this as
>> >> > > > > > > > > >>criticism, I know the history: we added in memory
>> >>queues
>> >> to
>> >> > > > help
>> >> > > > > > with
>> >> > > > > > > > > >>other
>> >> > > > > > > > > >>performance problems without thinking about
>> >>correctness,
>> >> > then
>> >> > > > we
>> >> > > > > > added
>> >> > > > > > > > > >>stuff to work around the in-memory queues not lose
>> >>data,
>> >> > and
>> >> > > > so on.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>Can we instead do the opposite exercise and start
>>with
>> >> the
>> >> > > > basics
>> >> > > > > > of
>> >> > > > > > > > what
>> >> > > > > > > > > >>mm should do and think about what deficiencies
>> >>prevents
>> >> > this
>> >> > > > > > approach
>> >> > > > > > > > > >>from
>> >> > > > > > > > > >>working? Then let's make sure the currently
>>in-flight
>> >> work
>> >> > will
>> >> > > > > > remove
>> >> > > > > > > > > >>these deficiencies. After all mm is kind of the
>> >> > prototypical
>> >> > > > kafka
>> >> > > > > > use
>> >> > > > > > > > > >>case
>> >> > > > > > > > > >>so if we can't make our clients to this probably no
>> >>one
>> >> > else
>> >> > > > can.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>I think mm should just be N independent threads
>>each
>> >>of
>> >> > which
>> >> > > > has
>> >> > > > > > their
>> >> > > > > > > > > >>own
>> >> > > > > > > > > >>consumer but share a producer and each of which
>>looks
>> >> like
>> >> > > > this:
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>while(true) {
>> >> > > > > > > > > >> val recs = consumer.poll(Long.MaxValue);
>> >> > > > > > > > > >> for (rec <- recs)
>> >> > > > > > > > > >> producer.send(rec, logErrorCallback)
>> >> > > > > > > > > >> if(System.currentTimeMillis - lastCommit >
>> >> > commitInterval)
>> >> > > > {
>> >> > > > > > > > > >> producer.flush()
>> >> > > > > > > > > >> consumer.commit()
>> >> > > > > > > > > >> lastCommit = System.currentTimeMillis
>> >> > > > > > > > > >> }
>> >> > > > > > > > > >>}
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>This will depend on setting the retry count in the
>> >> > producer to
>> >> > > > > > > > something
>> >> > > > > > > > > >>high with a largish backoff so that a failed send
>> >>attempt
>> >> > > > doesn't
>> >> > > > > > drop
>> >> > > > > > > > > >>data.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>We will need to use the callback to force a flush
>>and
>> >> > offset
>> >> > > > > > commit on
>> >> > > > > > > > > >>rebalance.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>This approach may have a few more TCP connections
>>due
>> >>to
>> >> > using
>> >> > > > > > multiple
>> >> > > > > > > > > >>consumers but I think it is a lot easier to reason
>> >>about
>> >> > and
>> >> > > > the
>> >> > > > > > total
>> >> > > > > > > > > >>number of mm instances is always going to be small.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>Let's talk about where this simple approach falls
>> >>short,
>> >> I
>> >> > > > think
>> >> > > > > > that
>> >> > > > > > > > > >>will
>> >> > > > > > > > > >>help us understand your motivations for additional
>> >> > elements.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>Another advantage of this is that it is so simple I
>> >>don't
>> >> > > > think we
>> >> > > > > > > > really
>> >> > > > > > > > > >>even need to both making mm extensible because
>>writing
>> >> > your own
>> >> > > > > > code
>> >> > > > > > > > that
>> >> > > > > > > > > >>does custom processing or transformation is just
>>ten
>> >> lines
>> >> > and
>> >> > > > no
>> >> > > > > > plug
>> >> > > > > > > > in
>> >> > > > > > > > > >>system is going to make it simpler.
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>-Jay
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>On Sun, Feb 8, 2015 at 2:40 PM, Neha Narkhede <
>> >> > > > n...@confluent.io>
>> >> > > > > > > > wrote:
>> >> > > > > > > > > >>
>> >> > > > > > > > > >>> Few comments -
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>> 1. Why do we need the message handler? Do you
>>have
>> >> > concrete
>> >> > > > use
>> >> > > > > > cases
>> >> > > > > > > > > >>>in
>> >> > > > > > > > > >>> mind? If not, we should consider adding it in the
>> >> future
>> >> > > > when/if
>> >> > > > > > we
>> >> > > > > > > > do
>> >> > > > > > > > > >>>have
>> >> > > > > > > > > >>> use cases for it. The purpose of the mirror maker
>> >>is a
>> >> > simple
>> >> > > > > > tool
>> >> > > > > > > > for
>> >> > > > > > > > > >>> setting up Kafka cluster replicas. I don't see
>>why
>> >>we
>> >> > need to
>> >> > > > > > > > include a
>> >> > > > > > > > > >>> message handler for doing stream transformations
>>or
>> >> > > > filtering.
>> >> > > > > > You
>> >> > > > > > > > can
>> >> > > > > > > > > >>> always write a simple process for doing that once
>> >>the
>> >> > data is
>> >> > > > > > copied
>> >> > > > > > > > as
>> >> > > > > > > > > >>>is
>> >> > > > > > > > > >>> in the target cluster
>> >> > > > > > > > > >>> 2. Why keep both designs? We should prefer the
>> >>simpler
>> >> > design
>> >> > > > > > unless
>> >> > > > > > > > it
>> >> > > > > > > > > >>>is
>> >> > > > > > > > > >>> not feasible due to the performance issue that we
>> >> > previously
>> >> > > > > > had. Did
>> >> > > > > > > > > >>>you
>> >> > > > > > > > > >>> get a chance to run some tests to see if that is
>> >>really
>> >> > > > still a
>> >> > > > > > > > problem
>> >> > > > > > > > > >>>or
>> >> > > > > > > > > >>> not? It will be easier to think about the design
>>and
>> >> also
>> >> > > > make
>> >> > > > > > the
>> >> > > > > > > > KIP
>> >> > > > > > > > > >>> complete if we make a call on the design first.
>> >> > > > > > > > > >>> 3. Can you explain the need for keeping a list of
>> >> unacked
>> >> > > > > > offsets per
>> >> > > > > > > > > >>> partition? Consider adding a section on retries
>>and
>> >>how
>> >> > you
>> >> > > > plan
>> >> > > > > > to
>> >> > > > > > > > > >>>handle
>> >> > > > > > > > > >>> the case when the producer runs out of all
>>retries.
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>> Thanks,
>> >> > > > > > > > > >>> Neha
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>> On Sun, Feb 8, 2015 at 2:06 PM, Jiangjie Qin
>> >> > > > > > > > > >>><j...@linkedin.com.invalid>
>> >> > > > > > > > > >>> wrote:
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>> > Hi Neha,
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > Yes, I’ve updated the KIP so the entire KIP is
>> >>based
>> >> > on new
>> >> > > > > > > > consumer
>> >> > > > > > > > > >>>now.
>> >> > > > > > > > > >>> > I’ve put both designs with and without data
>> >>channel
>> >> in
>> >> > the
>> >> > > > KIP
>> >> > > > > > as I
>> >> > > > > > > > > >>>still
>> >> > > > > > > > > >>> > feel we might need the data channel to provide
>> >>more
>> >> > > > > > flexibility,
>> >> > > > > > > > > >>> > especially after message handler is introduced.
>> >>I’ve
>> >> > put my
>> >> > > > > > > > thinking
>> >> > > > > > > > > >>>of
>> >> > > > > > > > > >>> > the pros and cons of the two designs in the
>>KIP as
>> >> > well.
>> >> > > > It’ll
>> >> > > > > > be
>> >> > > > > > > > > >>>great
>> >> > > > > > > > > >>> if
>> >> > > > > > > > > >>> > you can give a review and comment.
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > Thanks.
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > On 2/6/15, 7:30 PM, "Neha Narkhede" <
>> >> n...@confluent.io
>> >> > >
>> >> > > > wrote:
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > >Hey Becket,
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >What are the next steps on this KIP. As per
>>your
>> >> > comment
>> >> > > > > > earlier
>> >> > > > > > > > on
>> >> > > > > > > > > >>>the
>> >> > > > > > > > > >>> > >thread -
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >I do agree it makes more sense
>> >> > > > > > > > > >>> > >> to avoid duplicate effort and plan based on
>>new
>> >> > > > consumer.
>> >> > > > > > I’ll
>> >> > > > > > > > > >>>modify
>> >> > > > > > > > > >>> > >>the
>> >> > > > > > > > > >>> > >> KIP.
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >Did you get a chance to think about the
>> >>simplified
>> >> > design
>> >> > > > > > that we
>> >> > > > > > > > > >>> proposed
>> >> > > > > > > > > >>> > >earlier? Do you plan to update the KIP with
>>that
>> >> > proposal?
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >Thanks,
>> >> > > > > > > > > >>> > >Neha
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >On Wed, Feb 4, 2015 at 12:12 PM, Jiangjie Qin
>> >> > > > > > > > > >>><j...@linkedin.com.invalid
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> > >wrote:
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >> In mirror maker we do not do
>>de-serialization
>> >>on
>> >> the
>> >> > > > > > messages.
>> >> > > > > > > > > >>>Mirror
>> >> > > > > > > > > >>> > >> maker use source TopicPartition hash to
>>chose a
>> >> > > > producer to
>> >> > > > > > send
>> >> > > > > > > > > >>> > >>messages
>> >> > > > > > > > > >>> > >> from the same source partition. The
>>partition
>> >> those
>> >> > > > > > messages end
>> >> > > > > > > > > >>>up
>> >> > > > > > > > > >>> with
>> >> > > > > > > > > >>> > >> are decided by Partitioner class in
>> >>KafkaProducer
>> >> > > > (assuming
>> >> > > > > > you
>> >> > > > > > > > > >>>are
>> >> > > > > > > > > >>> > >>using
>> >> > > > > > > > > >>> > >> the new producer), which uses hash code of
>> >> bytes[].
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >> If deserialization is needed, it has to be
>> >>done in
>> >> > > > message
>> >> > > > > > > > > >>>handler.
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >> Thanks.
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >> Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >> On 2/4/15, 11:33 AM, "Bhavesh Mistry" <
>> >> > > > > > > > mistry.p.bhav...@gmail.com>
>> >> > > > > > > > > >>> > >>wrote:
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >> >Hi Jiangjie,
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >Thanks for entertaining my question so far.
>> >>Last
>> >> > > > > > question, I
>> >> > > > > > > > > >>>have is
>> >> > > > > > > > > >>> > >> >about
>> >> > > > > > > > > >>> > >> >serialization of message key. If the key
>> >> > > > de-serialization
>> >> > > > > > > > > >>>(Class) is
>> >> > > > > > > > > >>> > >>not
>> >> > > > > > > > > >>> > >> >present at the MM instance, then does it
>>use
>> >>raw
>> >> > byte
>> >> > > > > > hashcode
>> >> > > > > > > > to
>> >> > > > > > > > > >>> > >> >determine
>> >> > > > > > > > > >>> > >> >the partition ? How are you going to
>>address
>> >>the
>> >> > > > situation
>> >> > > > > > > > where
>> >> > > > > > > > > >>>key
>> >> > > > > > > > > >>> > >> >needs
>> >> > > > > > > > > >>> > >> >to be de-serialization and get actual
>>hashcode
>> >> > needs
>> >> > > > to be
>> >> > > > > > > > > >>>computed
>> >> > > > > > > > > >>> ?.
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >Thanks,
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >Bhavesh
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >On Fri, Jan 30, 2015 at 1:41 PM, Jiangjie
>>Qin
>> >> > > > > > > > > >>> > >><j...@linkedin.com.invalid>
>> >> > > > > > > > > >>> > >> >wrote:
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >> Hi Bhavesh,
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >> >> Please see inline comments.
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >> >> Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >> >> On 1/29/15, 7:00 PM, "Bhavesh Mistry"
>> >> > > > > > > > > >>><mistry.p.bhav...@gmail.com>
>> >> > > > > > > > > >>> > >> >>wrote:
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >> >> >Hi Jiangjie,
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >Thanks for the input.
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >a) Is MM will producer ack will be
>>attach
>> >>to
>> >> > > > Producer
>> >> > > > > > > > > >>>Instance or
>> >> > > > > > > > > >>> > >>per
>> >> > > > > > > > > >>> > >> >> >topic. Use case is that one instance
>>of MM
>> >> > > > > > > > > >>> > >> >> >needs to handle both strong ack and also
>> >>ack=0
>> >> > for
>> >> > > > some
>> >> > > > > > > > topic.
>> >> > > > > > > > > >>> Or
>> >> > > > > > > > > >>> > >>it
>> >> > > > > > > > > >>> > >> >> >would
>> >> > > > > > > > > >>> > >> >> >be better to set-up another instance of
>>MM.
>> >> > > > > > > > > >>> > >> >> The acks setting is producer level
>>setting
>> >> > instead of
>> >> > > > > > topic
>> >> > > > > > > > > >>>level
>> >> > > > > > > > > >>> > >> >>setting.
>> >> > > > > > > > > >>> > >> >> In this case you probably need to set up
>> >> another
>> >> > > > > > instance.
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >b) Regarding TCP connections, Why does
>> >> #producer
>> >> > > > > > instance
>> >> > > > > > > > > >>>attach
>> >> > > > > > > > > >>> to
>> >> > > > > > > > > >>> > >>TCP
>> >> > > > > > > > > >>> > >> >> >connection. Is it possible to use
>>Broker
>> >> > > > Connection TCP
>> >> > > > > > > > Pool,
>> >> > > > > > > > > >>> > >>producer
>> >> > > > > > > > > >>> > >> >> >will just checkout TCP connection to
>> >>Broker.
>> >> > So,
>> >> > > > # of
>> >> > > > > > > > > >>>Producer
>> >> > > > > > > > > >>> > >> >>Instance
>> >> > > > > > > > > >>> > >> >> >does not correlation to Brokers
>>Connection.
>> >> Is
>> >> > this
>> >> > > > > > > > possible
>> >> > > > > > > > > >>>?
>> >> > > > > > > > > >>> > >> >> In new producer, each producer maintains
>>a
>> >> > > > connection to
>> >> > > > > > each
>> >> > > > > > > > > >>> broker
>> >> > > > > > > > > >>> > >> >> within the producer instance. Making
>> >>producer
>> >> > > > instances
>> >> > > > > > to
>> >> > > > > > > > > >>>share
>> >> > > > > > > > > >>> the
>> >> > > > > > > > > >>> > >>TCP
>> >> > > > > > > > > >>> > >> >> connections is a very big change to the
>> >>current
>> >> > > > design,
>> >> > > > > > so I
>> >> > > > > > > > > >>> suppose
>> >> > > > > > > > > >>> > >>we
>> >> > > > > > > > > >>> > >> >> won’t be able to do that.
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >Thanks,
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >Bhavesh
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >On Thu, Jan 29, 2015 at 11:50 AM,
>>Jiangjie
>> >>Qin
>> >> > > > > > > > > >>> > >> >><j...@linkedin.com.invalid
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >wrote:
>> >> > > > > > > > > >>> > >> >> >
>> >> > > > > > > > > >>> > >> >> >> Hi Bhavesh,
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >> >> I think it is the right discussion to
>> >>have
>> >> > when
>> >> > > > we are
>> >> > > > > > > > > >>>talking
>> >> > > > > > > > > >>> > >>about
>> >> > > > > > > > > >>> > >> >>the
>> >> > > > > > > > > >>> > >> >> >> new new design for MM.
>> >> > > > > > > > > >>> > >> >> >> Please see the inline comments.
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >> >> Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >> >> On 1/28/15, 10:48 PM, "Bhavesh Mistry"
>> >> > > > > > > > > >>> > >><mistry.p.bhav...@gmail.com>
>> >> > > > > > > > > >>> > >> >> >>wrote:
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >Hi Jiangjie,
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >I just wanted to let you know about
>>our
>> >>use
>> >> > case
>> >> > > > and
>> >> > > > > > > > stress
>> >> > > > > > > > > >>>the
>> >> > > > > > > > > >>> > >> >>point
>> >> > > > > > > > > >>> > >> >> >>that
>> >> > > > > > > > > >>> > >> >> >> >local data center broker cluster have
>> >>fewer
>> >> > > > > > partitions
>> >> > > > > > > > than
>> >> > > > > > > > > >>>the
>> >> > > > > > > > > >>> > >> >> >> >destination
>> >> > > > > > > > > >>> > >> >> >> >offline broker cluster. Just because
>>we
>> >>do
>> >> > the
>> >> > > > batch
>> >> > > > > > pull
>> >> > > > > > > > > >>>from
>> >> > > > > > > > > >>> > >>CAMUS
>> >> > > > > > > > > >>> > >> >> >>and
>> >> > > > > > > > > >>> > >> >> >> >in
>> >> > > > > > > > > >>> > >> >> >> >order to drain data faster than the
>> >> injection
>> >> > > > rate
>> >> > > > > > (from
>> >> > > > > > > > > >>>four
>> >> > > > > > > > > >>> DCs
>> >> > > > > > > > > >>> > >> >>for
>> >> > > > > > > > > >>> > >> >> >>same
>> >> > > > > > > > > >>> > >> >> >> >topic).
>> >> > > > > > > > > >>> > >> >> >> Keeping the same partition number in
>> >>source
>> >> > and
>> >> > > > target
>> >> > > > > > > > > >>>cluster
>> >> > > > > > > > > >>> > >>will
>> >> > > > > > > > > >>> > >> >>be
>> >> > > > > > > > > >>> > >> >> >>an
>> >> > > > > > > > > >>> > >> >> >> option but will not be enforced by
>> >>default.
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >We are facing following issues
>>(probably
>> >> due
>> >> > to
>> >> > > > > > > > > >>>configuration):
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >1) We occasionally loose data
>>due
>> >>to
>> >> > message
>> >> > > > > > batch
>> >> > > > > > > > > >>>size is
>> >> > > > > > > > > >>> > >>too
>> >> > > > > > > > > >>> > >> >> >>large
>> >> > > > > > > > > >>> > >> >> >> >(2MB) on target data (we are using
>>old
>> >> > producer
>> >> > > > but I
>> >> > > > > > > > think
>> >> > > > > > > > > >>>new
>> >> > > > > > > > > >>> > >> >> >>producer
>> >> > > > > > > > > >>> > >> >> >> >will solve this problem to some
>>extend).
>> >> > > > > > > > > >>> > >> >> >> We do see this issue in LinkedIn as
>>well.
>> >> New
>> >> > > > producer
>> >> > > > > > > > also
>> >> > > > > > > > > >>> might
>> >> > > > > > > > > >>> > >> >>have
>> >> > > > > > > > > >>> > >> >> >> this issue. There are some proposal of
>> >> > solutions,
>> >> > > > but
>> >> > > > > > no
>> >> > > > > > > > > >>>real
>> >> > > > > > > > > >>> work
>> >> > > > > > > > > >>> > >> >> >>started
>> >> > > > > > > > > >>> > >> >> >> yet. For now, as a workaround,
>>setting a
>> >> more
>> >> > > > > > aggressive
>> >> > > > > > > > > >>>batch
>> >> > > > > > > > > >>> > >>size
>> >> > > > > > > > > >>> > >> >>on
>> >> > > > > > > > > >>> > >> >> >> producer side should work.
>> >> > > > > > > > > >>> > >> >> >> >2) Since only one instance is
>>set
>> >>to
>> >> MM
>> >> > > > data,
>> >> > > > > > we
>> >> > > > > > > > are
>> >> > > > > > > > > >>>not
>> >> > > > > > > > > >>> > >>able
>> >> > > > > > > > > >>> > >> >>to
>> >> > > > > > > > > >>> > >> >> >> >set-up ack per topic instead ack is
>> >> attached
>> >> > to
>> >> > > > > > producer
>> >> > > > > > > > > >>> > >>instance.
>> >> > > > > > > > > >>> > >> >> >> I don’t quite get the question here.
>> >> > > > > > > > > >>> > >> >> >> >3) How are you going to address
>>two
>> >> > phase
>> >> > > > commit
>> >> > > > > > > > > >>>problem
>> >> > > > > > > > > >>> if
>> >> > > > > > > > > >>> > >> >>ack is
>> >> > > > > > > > > >>> > >> >> >> >set
>> >> > > > > > > > > >>> > >> >> >> >to strongest, but auto commit is on
>>for
>> >> > consumer
>> >> > > > > > (meaning
>> >> > > > > > > > > >>> > >>producer
>> >> > > > > > > > > >>> > >> >>does
>> >> > > > > > > > > >>> > >> >> >> >not
>> >> > > > > > > > > >>> > >> >> >> >get ack, but consumer auto committed
>> >> offset
>> >> > that
>> >> > > > > > > > message).
>> >> > > > > > > > > >>> Is
>> >> > > > > > > > > >>> > >> >>there
>> >> > > > > > > > > >>> > >> >> >> >transactional (Kafka transaction is
>>in
>> >> > process)
>> >> > > > > > based ack
>> >> > > > > > > > > >>>and
>> >> > > > > > > > > >>> > >>commit
>> >> > > > > > > > > >>> > >> >> >> >offset
>> >> > > > > > > > > >>> > >> >> >> >?
>> >> > > > > > > > > >>> > >> >> >> Auto offset commit should be turned
>>off
>> >>in
>> >> > this
>> >> > > > case.
>> >> > > > > > The
>> >> > > > > > > > > >>>offset
>> >> > > > > > > > > >>> > >>will
>> >> > > > > > > > > >>> > >> >> >>only
>> >> > > > > > > > > >>> > >> >> >> be committed once by the offset commit
>> >> > thread. So
>> >> > > > > > there is
>> >> > > > > > > > > >>>no
>> >> > > > > > > > > >>> two
>> >> > > > > > > > > >>> > >> >>phase
>> >> > > > > > > > > >>> > >> >> >> commit.
>> >> > > > > > > > > >>> > >> >> >> >4) How are you planning to avoid
>> >> > duplicated
>> >> > > > > > message?
>> >> > > > > > > > > >>>( Is
>> >> > > > > > > > > >>> > >> >> >> >brokergoing
>> >> > > > > > > > > >>> > >> >> >> >have moving window of message
>>collected
>> >>and
>> >> > > > de-dupe
>> >> > > > > > ?)
>> >> > > > > > > > > >>> > >>Possibly, we
>> >> > > > > > > > > >>> > >> >> >>get
>> >> > > > > > > > > >>> > >> >> >> >this from retry set to 5…?
>> >> > > > > > > > > >>> > >> >> >> We are not trying to completely avoid
>> >> > duplicates.
>> >> > > > The
>> >> > > > > > > > > >>>duplicates
>> >> > > > > > > > > >>> > >>will
>> >> > > > > > > > > >>> > >> >> >> still be there if:
>> >> > > > > > > > > >>> > >> >> >> 1. Producer retries on failure.
>> >> > > > > > > > > >>> > >> >> >> 2. Mirror maker is hard killed.
>> >> > > > > > > > > >>> > >> >> >> Currently, dedup is expected to be
>>done
>> >>by
>> >> > user if
>> >> > > > > > > > > >>>necessary.
>> >> > > > > > > > > >>> > >> >> >> >5) Last, is there any warning or
>> >>any
>> >> > thing
>> >> > > > you
>> >> > > > > > can
>> >> > > > > > > > > >>>provide
>> >> > > > > > > > > >>> > >> >>insight
>> >> > > > > > > > > >>> > >> >> >> >from MM component about data
>>injection
>> >>rate
>> >> > into
>> >> > > > > > > > > >>>destination
>> >> > > > > > > > > >>> > >> >> >>partitions is
>> >> > > > > > > > > >>> > >> >> >> >NOT evenly distributed regardless of
>> >> keyed
>> >> > or
>> >> > > > > > non-keyed
>> >> > > > > > > > > >>> message
>> >> > > > > > > > > >>> > >> >> >>(Hence
>> >> > > > > > > > > >>> > >> >> >> >there is ripple effect such as data
>>not
>> >> > arriving
>> >> > > > > > late, or
>> >> > > > > > > > > >>>data
>> >> > > > > > > > > >>> is
>> >> > > > > > > > > >>> > >> >> >>arriving
>> >> > > > > > > > > >>> > >> >> >> >out of order in intern of time stamp
>> >>and
>> >> > early
>> >> > > > some
>> >> > > > > > > > time,
>> >> > > > > > > > > >>>and
>> >> > > > > > > > > >>> > >> >>CAMUS
>> >> > > > > > > > > >>> > >> >> >> >creates huge number of file count on
>> >>HDFS
>> >> > due to
>> >> > > > > > uneven
>> >> > > > > > > > > >>> injection
>> >> > > > > > > > > >>> > >> >>rate
>> >> > > > > > > > > >>> > >> >> >>.
>> >> > > > > > > > > >>> > >> >> >> >Camus Job is configured to run
>>every 3
>> >> > minutes.)
>> >> > > > > > > > > >>> > >> >> >> I think uneven data distribution is
>> >> typically
>> >> > > > caused
>> >> > > > > > by
>> >> > > > > > > > > >>>server
>> >> > > > > > > > > >>> > >>side
>> >> > > > > > > > > >>> > >> >> >> unbalance, instead of something mirror
>> >>maker
>> >> > could
>> >> > > > > > > > control.
>> >> > > > > > > > > >>>In
>> >> > > > > > > > > >>> new
>> >> > > > > > > > > >>> > >> >> >>mirror
>> >> > > > > > > > > >>> > >> >> >> maker, however, there is a
>>customizable
>> >> > message
>> >> > > > > > handler,
>> >> > > > > > > > > >>>that
>> >> > > > > > > > > >>> > >>might
>> >> > > > > > > > > >>> > >> >>be
>> >> > > > > > > > > >>> > >> >> >> able to help a little bit. In message
>> >> handler,
>> >> > > > you can
>> >> > > > > > > > > >>> explicitly
>> >> > > > > > > > > >>> > >> >>set a
>> >> > > > > > > > > >>> > >> >> >> partition that you want to produce the
>> >> message
>> >> > > > to. So
>> >> > > > > > if
>> >> > > > > > > > you
>> >> > > > > > > > > >>> know
>> >> > > > > > > > > >>> > >>the
>> >> > > > > > > > > >>> > >> >> >> uneven data distribution in target
>> >>cluster,
>> >> > you
>> >> > > > may
>> >> > > > > > offset
>> >> > > > > > > > > >>>it
>> >> > > > > > > > > >>> > >>here.
>> >> > > > > > > > > >>> > >> >>But
>> >> > > > > > > > > >>> > >> >> >> that probably only works for non-keyed
>> >> > messages.
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >I am not sure if this is right
>> >>discussion
>> >> > form to
>> >> > > > > > bring
>> >> > > > > > > > > >>>these
>> >> > > > > > > > > >>> to
>> >> > > > > > > > > >>> > >> >> >> >your/kafka
>> >> > > > > > > > > >>> > >> >> >> >Dev team attention. This might be
>>off
>> >> track,
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >Thanks,
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >Bhavesh
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >On Wed, Jan 28, 2015 at 11:07 AM,
>> >>Jiangjie
>> >> > Qin
>> >> > > > > > > > > >>> > >> >> >><j...@linkedin.com.invalid
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >wrote:
>> >> > > > > > > > > >>> > >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> I’ve updated the KIP page.
>>Feedbacks
>> >>are
>> >> > > > welcome.
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> Regarding the simple mirror maker
>> >> design. I
>> >> > > > thought
>> >> > > > > > > > over
>> >> > > > > > > > > >>>it
>> >> > > > > > > > > >>> and
>> >> > > > > > > > > >>> > >> >>have
>> >> > > > > > > > > >>> > >> >> >> >>some
>> >> > > > > > > > > >>> > >> >> >> >> worries:
>> >> > > > > > > > > >>> > >> >> >> >> There are two things that might
>>worth
>> >> > thinking:
>> >> > > > > > > > > >>> > >> >> >> >> 1. One of the enhancement to mirror
>> >>maker
>> >> > is
>> >> > > > > > adding a
>> >> > > > > > > > > >>>message
>> >> > > > > > > > > >>> > >> >> >>handler to
>> >> > > > > > > > > >>> > >> >> >> >> do things like reformatting. I
>>think
>> >>we
>> >> > might
>> >> > > > > > > > potentially
>> >> > > > > > > > > >>> want
>> >> > > > > > > > > >>> > >>to
>> >> > > > > > > > > >>> > >> >> >>have
>> >> > > > > > > > > >>> > >> >> >> >> more threads processing the
>>messages
>> >>than
>> >> > the
>> >> > > > > > number of
>> >> > > > > > > > > >>> > >>consumers.
>> >> > > > > > > > > >>> > >> >> >>If we
>> >> > > > > > > > > >>> > >> >> >> >> follow the simple mirror maker
>> >>solution,
>> >> we
>> >> > > > lose
>> >> > > > > > this
>> >> > > > > > > > > >>> > >>flexibility.
>> >> > > > > > > > > >>> > >> >> >> >> 2. This might not matter too much,
>>but
>> >> > creating
>> >> > > > > > more
>> >> > > > > > > > > >>> consumers
>> >> > > > > > > > > >>> > >> >>means
>> >> > > > > > > > > >>> > >> >> >> >>more
>> >> > > > > > > > > >>> > >> >> >> >> footprint of TCP connection /
>>memory.
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> Any thoughts on this?
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> Thanks.
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> On 1/26/15, 10:35 AM, "Jiangjie
>>Qin" <
>> >> > > > > > > > j...@linkedin.com>
>> >> > > > > > > > > >>> > wrote:
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >Hi Jay and Neha,
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >Thanks a lot for the reply and
>> >> > explanation. I
>> >> > > > do
>> >> > > > > > agree
>> >> > > > > > > > > >>>it
>> >> > > > > > > > > >>> > >>makes
>> >> > > > > > > > > >>> > >> >>more
>> >> > > > > > > > > >>> > >> >> >> >>sense
>> >> > > > > > > > > >>> > >> >> >> >> >to avoid duplicate effort and plan
>> >>based
>> >> > on
>> >> > > > new
>> >> > > > > > > > > >>>consumer.
>> >> > > > > > > > > >>> I’ll
>> >> > > > > > > > > >>> > >> >> >>modify
>> >> > > > > > > > > >>> > >> >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >KIP.
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >To Jay’s question on message
>> >>ordering -
>> >> > The
>> >> > > > data
>> >> > > > > > > > channel
>> >> > > > > > > > > >>> > >> >>selection
>> >> > > > > > > > > >>> > >> >> >> >>makes
>> >> > > > > > > > > >>> > >> >> >> >> >sure that the messages from the
>>same
>> >> > source
>> >> > > > > > partition
>> >> > > > > > > > > >>>will
>> >> > > > > > > > > >>> > >>sent
>> >> > > > > > > > > >>> > >> >>by
>> >> > > > > > > > > >>> > >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >same producer. So the order of the
>> >> > messages is
>> >> > > > > > > > > >>>guaranteed
>> >> > > > > > > > > >>> with
>> >> > > > > > > > > >>> > >> >> >>proper
>> >> > > > > > > > > >>> > >> >> >> >> >producer settings
>> >> > > > > > > > > >>> > >>
>> >>>>(MaxInFlightRequests=1,retries=Integer.MaxValue,
>> >> > > > > > > > > >>> > >> >> >> >>etc.)
>> >> > > > > > > > > >>> > >> >> >> >> >For keyed messages, because they
>>come
>> >> > from the
>> >> > > > > > same
>> >> > > > > > > > > >>>source
>> >> > > > > > > > > >>> > >> >>partition
>> >> > > > > > > > > >>> > >> >> >> >>and
>> >> > > > > > > > > >>> > >> >> >> >> >will end up in the same target
>> >> partition,
>> >> > as
>> >> > > > long
>> >> > > > > > as
>> >> > > > > > > > > >>>they
>> >> > > > > > > > > >>> are
>> >> > > > > > > > > >>> > >> >>sent
>> >> > > > > > > > > >>> > >> >> >>by
>> >> > > > > > > > > >>> > >> >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >same producer, the order is
>> >>guaranteed.
>> >> > > > > > > > > >>> > >> >> >> >> >For non-keyed messages, the
>>messages
>> >> > coming
>> >> > > > from
>> >> > > > > > the
>> >> > > > > > > > > >>>same
>> >> > > > > > > > > >>> > >>source
>> >> > > > > > > > > >>> > >> >> >> >>partition
>> >> > > > > > > > > >>> > >> >> >> >> >might go to different target
>> >>partitions.
>> >> > The
>> >> > > > > > order is
>> >> > > > > > > > > >>>only
>> >> > > > > > > > > >>> > >> >> >>guaranteed
>> >> > > > > > > > > >>> > >> >> >> >> >within each partition.
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >Anyway, I’ll modify the KIP and
>>data
>> >> > channel
>> >> > > > will
>> >> > > > > > be
>> >> > > > > > > > > >>>away.
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >Thanks.
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >On 1/25/15, 4:34 PM, "Neha
>>Narkhede"
>> >><
>> >> > > > > > > > n...@confluent.io>
>> >> > > > > > > > > >>> > >>wrote:
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >> >>I think there is some value in
>> >> > investigating
>> >> > > > if
>> >> > > > > > we
>> >> > > > > > > > can
>> >> > > > > > > > > >>>go
>> >> > > > > > > > > >>> > >>back
>> >> > > > > > > > > >>> > >> >>to
>> >> > > > > > > > > >>> > >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>simple mirror maker design, as
>>Jay
>> >> points
>> >> > > > out.
>> >> > > > > > Here
>> >> > > > > > > > you
>> >> > > > > > > > > >>> have
>> >> > > > > > > > > >>> > >>N
>> >> > > > > > > > > >>> > >> >> >> >>threads,
>> >> > > > > > > > > >>> > >> >> >> >> >>each has a consumer and a
>>producer.
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>The reason why we had to move
>>away
>> >>from
>> >> > that
>> >> > > > was
>> >> > > > > > a
>> >> > > > > > > > > >>> > >>combination
>> >> > > > > > > > > >>> > >> >>of
>> >> > > > > > > > > >>> > >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>difference in throughput between
>>the
>> >> > consumer
>> >> > > > > > and the
>> >> > > > > > > > > >>>old
>> >> > > > > > > > > >>> > >> >>producer
>> >> > > > > > > > > >>> > >> >> >>and
>> >> > > > > > > > > >>> > >> >> >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>deficiency of the consumer
>> >>rebalancing
>> >> > that
>> >> > > > > > limits
>> >> > > > > > > > the
>> >> > > > > > > > > >>> total
>> >> > > > > > > > > >>> > >> >> >>number of
>> >> > > > > > > > > >>> > >> >> >> >> >>mirror maker threads. So the only
>> >> option
>> >> > > > > > available
>> >> > > > > > > > was
>> >> > > > > > > > > >>>to
>> >> > > > > > > > > >>> > >> >>increase
>> >> > > > > > > > > >>> > >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>throughput of the limited # of
>> >>mirror
>> >> > maker
>> >> > > > > > threads
>> >> > > > > > > > > >>>that
>> >> > > > > > > > > >>> > >>could
>> >> > > > > > > > > >>> > >> >>be
>> >> > > > > > > > > >>> > >> >> >> >> >>deployed.
>> >> > > > > > > > > >>> > >> >> >> >> >>Now that queuing design may not
>>make
>> >> > sense,
>> >> > > > if
>> >> > > > > > the
>> >> > > > > > > > new
>> >> > > > > > > > > >>> > >> >>producer's
>> >> > > > > > > > > >>> > >> >> >> >> >>throughput is almost similar to
>>the
>> >> > consumer
>> >> > > > AND
>> >> > > > > > the
>> >> > > > > > > > > >>>fact
>> >> > > > > > > > > >>> > >>that
>> >> > > > > > > > > >>> > >> >>the
>> >> > > > > > > > > >>> > >> >> >>new
>> >> > > > > > > > > >>> > >> >> >> >> >>round-robin based consumer
>> >>rebalancing
>> >> > can
>> >> > > > allow
>> >> > > > > > a
>> >> > > > > > > > very
>> >> > > > > > > > > >>> high
>> >> > > > > > > > > >>> > >> >> >>number of
>> >> > > > > > > > > >>> > >> >> >> >> >>mirror maker instances to exist.
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>This is the end state that the
>> >>mirror
>> >> > maker
>> >> > > > > > should be
>> >> > > > > > > > > >>>in
>> >> > > > > > > > > >>> once
>> >> > > > > > > > > >>> > >> >>the
>> >> > > > > > > > > >>> > >> >> >>new
>> >> > > > > > > > > >>> > >> >> >> >> >>consumer is complete, so it
>>wouldn't
>> >> > hurt to
>> >> > > > see
>> >> > > > > > if
>> >> > > > > > > > we
>> >> > > > > > > > > >>>can
>> >> > > > > > > > > >>> > >>just
>> >> > > > > > > > > >>> > >> >> >>move
>> >> > > > > > > > > >>> > >> >> >> >>to
>> >> > > > > > > > > >>> > >> >> >> >> >>that right now.
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>On Fri, Jan 23, 2015 at 8:40 PM,
>>Jay
>> >> > Kreps
>> >> > > > > > > > > >>> > >><jay.kr...@gmail.com
>> >> > > > > > > > > >>> > >> >
>> >> > > > > > > > > >>> > >> >> >> >>wrote:
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>> QQ: If we ever use a different
>> >> > technique
>> >> > > > for
>> >> > > > > > the
>> >> > > > > > > > data
>> >> > > > > > > > > >>> > >>channel
>> >> > > > > > > > > >>> > >> >> >> >>selection
>> >> > > > > > > > > >>> > >> >> >> >> >>> than for the producer
>>partitioning
>> >> > won't
>> >> > > > that
>> >> > > > > > break
>> >> > > > > > > > > >>> > >>ordering?
>> >> > > > > > > > > >>> > >> >>How
>> >> > > > > > > > > >>> > >> >> >> >>can
>> >> > > > > > > > > >>> > >> >> >> >> >>>we
>> >> > > > > > > > > >>> > >> >> >> >> >>> ensure these things stay in
>>sync?
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>> With respect to the new
>> >>consumer--I
>> >> > really
>> >> > > > do
>> >> > > > > > want
>> >> > > > > > > > to
>> >> > > > > > > > > >>> > >> >>encourage
>> >> > > > > > > > > >>> > >> >> >> >>people
>> >> > > > > > > > > >>> > >> >> >> >> >>>to
>> >> > > > > > > > > >>> > >> >> >> >> >>> think through how MM will work
>> >>with
>> >> > the new
>> >> > > > > > > > consumer.
>> >> > > > > > > > > >>>I
>> >> > > > > > > > > >>> > >>mean
>> >> > > > > > > > > >>> > >> >>this
>> >> > > > > > > > > >>> > >> >> >> >>isn't
>> >> > > > > > > > > >>> > >> >> >> >> >>> very far off, maybe a few
>>months
>> >>if
>> >> we
>> >> > > > hustle?
>> >> > > > > > I
>> >> > > > > > > > > >>>could
>> >> > > > > > > > > >>> > >> >>imagine us
>> >> > > > > > > > > >>> > >> >> >> >> >>>getting
>> >> > > > > > > > > >>> > >> >> >> >> >>> this mm fix done maybe sooner,
>> >>maybe
>> >> > in a
>> >> > > > > > month?
>> >> > > > > > > > So I
>> >> > > > > > > > > >>> guess
>> >> > > > > > > > > >>> > >> >>this
>> >> > > > > > > > > >>> > >> >> >> >>buys
>> >> > > > > > > > > >>> > >> >> >> >> >>>us an
>> >> > > > > > > > > >>> > >> >> >> >> >>> extra month before we rip it
>>out
>> >>and
>> >> > throw
>> >> > > > it
>> >> > > > > > away?
>> >> > > > > > > > > >>>Maybe
>> >> > > > > > > > > >>> > >>two?
>> >> > > > > > > > > >>> > >> >> >>This
>> >> > > > > > > > > >>> > >> >> >> >>bug
>> >> > > > > > > > > >>> > >> >> >> >> >>>has
>> >> > > > > > > > > >>> > >> >> >> >> >>> been there for a while, though,
>> >> right?
>> >> > Is
>> >> > > > it
>> >> > > > > > worth
>> >> > > > > > > > > >>>it?
>> >> > > > > > > > > >>> > >> >>Probably
>> >> > > > > > > > > >>> > >> >> >>it
>> >> > > > > > > > > >>> > >> >> >> >>is,
>> >> > > > > > > > > >>> > >> >> >> >> >>>but
>> >> > > > > > > > > >>> > >> >> >> >> >>> it still kind of sucks to have
>>the
>> >> > > > duplicate
>> >> > > > > > > > effort.
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>> So anyhow let's definitely
>>think
>> >> about
>> >> > how
>> >> > > > > > things
>> >> > > > > > > > > >>>will
>> >> > > > > > > > > >>> work
>> >> > > > > > > > > >>> > >> >>with
>> >> > > > > > > > > >>> > >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>>new
>> >> > > > > > > > > >>> > >> >> >> >> >>> consumer. I think we can
>>probably
>> >> just
>> >> > > > have N
>> >> > > > > > > > > >>>threads,
>> >> > > > > > > > > >>> each
>> >> > > > > > > > > >>> > >> >> >>thread
>> >> > > > > > > > > >>> > >> >> >> >>has
>> >> > > > > > > > > >>> > >> >> >> >> >>>a
>> >> > > > > > > > > >>> > >> >> >> >> >>> producer and consumer and is
>> >> internally
>> >> > > > single
>> >> > > > > > > > > >>>threaded.
>> >> > > > > > > > > >>> > >>Any
>> >> > > > > > > > > >>> > >> >> >>reason
>> >> > > > > > > > > >>> > >> >> >> >> >>>this
>> >> > > > > > > > > >>> > >> >> >> >> >>> wouldn't work?
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>> -Jay
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>> On Wed, Jan 21, 2015 at 5:29
>>PM,
>> >> > Jiangjie
>> >> > > > Qin
>> >> > > > > > > > > >>> > >> >> >> >> >>><j...@linkedin.com.invalid>
>> >> > > > > > > > > >>> > >> >> >> >> >>> wrote:
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Hi Jay,
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Thanks for comments. Please
>>see
>> >> > inline
>> >> > > > > > responses.
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > On 1/21/15, 1:33 PM, "Jay
>>Kreps"
>> >> > > > > > > > > >>><jay.kr...@gmail.com>
>> >> > > > > > > > > >>> > >> >>wrote:
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >Hey guys,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >A couple questions/comments:
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >1. The callback and
>> >> user-controlled
>> >> > > > commit
>> >> > > > > > > > offset
>> >> > > > > > > > > >>> > >> >> >>functionality
>> >> > > > > > > > > >>> > >> >> >> >>is
>> >> > > > > > > > > >>> > >> >> >> >> >>> already
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >in the new consumer which we
>> >>are
>> >> > > > working on
>> >> > > > > > in
>> >> > > > > > > > > >>> parallel.
>> >> > > > > > > > > >>> > >> >>If we
>> >> > > > > > > > > >>> > >> >> >> >> >>> accelerated
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >that work it might help
>> >> concentrate
>> >> > > > > > efforts. I
>> >> > > > > > > > > >>>admit
>> >> > > > > > > > > >>> > >>this
>> >> > > > > > > > > >>> > >> >> >>might
>> >> > > > > > > > > >>> > >> >> >> >>take
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >slightly longer in calendar
>> >>time
>> >> but
>> >> > > > could
>> >> > > > > > still
>> >> > > > > > > > > >>> > >>probably
>> >> > > > > > > > > >>> > >> >>get
>> >> > > > > > > > > >>> > >> >> >> >>done
>> >> > > > > > > > > >>> > >> >> >> >> >>>this
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >quarter. Have you guys
>> >>considered
>> >> > that
>> >> > > > > > approach?
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Yes, I totally agree that
>> >>ideally
>> >> we
>> >> > > > should
>> >> > > > > > put
>> >> > > > > > > > > >>>efforts
>> >> > > > > > > > > >>> > >>on
>> >> > > > > > > > > >>> > >> >>new
>> >> > > > > > > > > >>> > >> >> >> >> >>>consumer.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > The main reason for still
>> >>working
>> >> on
>> >> > the
>> >> > > > old
>> >> > > > > > > > > >>>consumer
>> >> > > > > > > > > >>> is
>> >> > > > > > > > > >>> > >> >>that
>> >> > > > > > > > > >>> > >> >> >>we
>> >> > > > > > > > > >>> > >> >> >> >> >>>expect
>> >> > > > > > > > > >>> > >> >> >> >> >>> it
>> >> > > > > > > > > >>> > >> >> >> >> >>> > would still be used in
>>LinkedIn
>> >>for
>> >> > > > quite a
>> >> > > > > > while
>> >> > > > > > > > > >>> before
>> >> > > > > > > > > >>> > >>the
>> >> > > > > > > > > >>> > >> >> >>new
>> >> > > > > > > > > >>> > >> >> >> >> >>>consumer
>> >> > > > > > > > > >>> > >> >> >> >> >>> > could be fully rolled out.
>>And
>> >>we
>> >> > > > recently
>> >> > > > > > > > > >>>suffering a
>> >> > > > > > > > > >>> > >>lot
>> >> > > > > > > > > >>> > >> >>from
>> >> > > > > > > > > >>> > >> >> >> >> >>>mirror
>> >> > > > > > > > > >>> > >> >> >> >> >>> > maker data loss issue. So our
>> >> current
>> >> > > > plan is
>> >> > > > > > > > > >>>making
>> >> > > > > > > > > >>> > >> >>necessary
>> >> > > > > > > > > >>> > >> >> >> >> >>>changes to
>> >> > > > > > > > > >>> > >> >> >> >> >>> > make current mirror maker
>> >>stable in
>> >> > > > > > production.
>> >> > > > > > > > > >>>Then we
>> >> > > > > > > > > >>> > >>can
>> >> > > > > > > > > >>> > >> >> >>test
>> >> > > > > > > > > >>> > >> >> >> >>and
>> >> > > > > > > > > >>> > >> >> >> >> >>> > rollout new consumer
>>gradually
>> >> > without
>> >> > > > > > getting
>> >> > > > > > > > > >>>burnt.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >2. I think partitioning on
>>the
>> >> hash
>> >> > of
>> >> > > > the
>> >> > > > > > topic
>> >> > > > > > > > > >>> > >>partition
>> >> > > > > > > > > >>> > >> >>is
>> >> > > > > > > > > >>> > >> >> >> >>not a
>> >> > > > > > > > > >>> > >> >> >> >> >>>very
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >good idea because that will
>> >>make
>> >> the
>> >> > > > case of
>> >> > > > > > > > going
>> >> > > > > > > > > >>> from
>> >> > > > > > > > > >>> > >>a
>> >> > > > > > > > > >>> > >> >> >>cluster
>> >> > > > > > > > > >>> > >> >> >> >> >>>with
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >fewer partitions to one with
>> >>more
>> >> > > > > > partitions not
>> >> > > > > > > > > >>> work. I
>> >> > > > > > > > > >>> > >> >> >>think an
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >intuitive
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >way to do this would be the
>> >> > following:
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >a. Default behavior: Just do
>> >>what
>> >> > the
>> >> > > > > > producer
>> >> > > > > > > > > >>>does.
>> >> > > > > > > > > >>> > >>I.e.
>> >> > > > > > > > > >>> > >> >>if
>> >> > > > > > > > > >>> > >> >> >>you
>> >> > > > > > > > > >>> > >> >> >> >> >>> specify a
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >key use it for
>>partitioning, if
>> >> not
>> >> > just
>> >> > > > > > > > partition
>> >> > > > > > > > > >>>in
>> >> > > > > > > > > >>> a
>> >> > > > > > > > > >>> > >> >> >> >>round-robin
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >fashion.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >b. Add a
>>--preserve-partition
>> >> option
>> >> > > > that
>> >> > > > > > will
>> >> > > > > > > > > >>> > >>explicitly
>> >> > > > > > > > > >>> > >> >> >> >>inherent
>> >> > > > > > > > > >>> > >> >> >> >> >>>the
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >partition from the source
>> >> > irrespective
>> >> > > > of
>> >> > > > > > > > whether
>> >> > > > > > > > > >>> there
>> >> > > > > > > > > >>> > >>is
>> >> > > > > > > > > >>> > >> >>a
>> >> > > > > > > > > >>> > >> >> >>key
>> >> > > > > > > > > >>> > >> >> >> >>or
>> >> > > > > > > > > >>> > >> >> >> >> >>> which
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >partition that key would
>>hash
>> >>to.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Sorry that I did not explain
>> >>this
>> >> > clear
>> >> > > > > > enough.
>> >> > > > > > > > The
>> >> > > > > > > > > >>> hash
>> >> > > > > > > > > >>> > >>of
>> >> > > > > > > > > >>> > >> >> >>topic
>> >> > > > > > > > > >>> > >> >> >> >> >>> > partition is only used when
>> >>decide
>> >> > which
>> >> > > > > > mirror
>> >> > > > > > > > > >>>maker
>> >> > > > > > > > > >>> > >>data
>> >> > > > > > > > > >>> > >> >> >>channel
>> >> > > > > > > > > >>> > >> >> >> >> >>>queue
>> >> > > > > > > > > >>> > >> >> >> >> >>> > the consumer thread should
>>put
>> >> > message
>> >> > > > into.
>> >> > > > > > It
>> >> > > > > > > > > >>>only
>> >> > > > > > > > > >>> > >>tries
>> >> > > > > > > > > >>> > >> >>to
>> >> > > > > > > > > >>> > >> >> >>make
>> >> > > > > > > > > >>> > >> >> >> >> >>>sure
>> >> > > > > > > > > >>> > >> >> >> >> >>> > the messages from the same
>> >> partition
>> >> > is
>> >> > > > sent
>> >> > > > > > by
>> >> > > > > > > > the
>> >> > > > > > > > > >>> same
>> >> > > > > > > > > >>> > >> >> >>producer
>> >> > > > > > > > > >>> > >> >> >> >> >>>thread
>> >> > > > > > > > > >>> > >> >> >> >> >>> > to guarantee the sending
>>order.
>> >> This
>> >> > is
>> >> > > > not
>> >> > > > > > at
>> >> > > > > > > > all
>> >> > > > > > > > > >>> > >>related
>> >> > > > > > > > > >>> > >> >>to
>> >> > > > > > > > > >>> > >> >> >> >>which
>> >> > > > > > > > > >>> > >> >> >> >> >>> > partition in target cluster
>>the
>> >> > messages
>> >> > > > end
>> >> > > > > > up.
>> >> > > > > > > > > >>>That
>> >> > > > > > > > > >>> is
>> >> > > > > > > > > >>> > >> >>still
>> >> > > > > > > > > >>> > >> >> >> >> >>>decided by
>> >> > > > > > > > > >>> > >> >> >> >> >>> > producer.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >3. You don't actually give
>>the
>> >> > > > > > > > > >>> ConsumerRebalanceListener
>> >> > > > > > > > > >>> > >> >> >> >>interface.
>> >> > > > > > > > > >>> > >> >> >> >> >>>What
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >is
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >that going to look like?
>> >> > > > > > > > > >>> > >> >> >> >> >>> > Good point! I should have put
>> >>it in
>> >> > the
>> >> > > > > > wiki. I
>> >> > > > > > > > > >>>just
>> >> > > > > > > > > >>> > >>added
>> >> > > > > > > > > >>> > >> >>it.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >4. What is
>>MirrorMakerRecord? I
>> >> > think
>> >> > > > > > ideally
>> >> > > > > > > > the
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >MirrorMakerMessageHandler
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >interface would take a
>> >> > ConsumerRecord as
>> >> > > > > > input
>> >> > > > > > > > and
>> >> > > > > > > > > >>> > >>return a
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >ProducerRecord,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >right? That would allow you
>>to
>> >> > > > transform the
>> >> > > > > > > > key,
>> >> > > > > > > > > >>> value,
>> >> > > > > > > > > >>> > >> >> >> >>partition,
>> >> > > > > > > > > >>> > >> >> >> >> >>>or
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >destination topic...
>> >> > > > > > > > > >>> > >> >> >> >> >>> > MirrorMakerRecord is
>>introduced
>> >>in
>> >> > > > > > KAFKA-1650,
>> >> > > > > > > > > >>>which is
>> >> > > > > > > > > >>> > >> >>exactly
>> >> > > > > > > > > >>> > >> >> >> >>the
>> >> > > > > > > > > >>> > >> >> >> >> >>>same
>> >> > > > > > > > > >>> > >> >> >> >> >>> > as ConsumerRecord in
>>KAFKA-1760.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > private[kafka] class
>> >> > MirrorMakerRecord
>> >> > > > (val
>> >> > > > > > > > > >>> sourceTopic:
>> >> > > > > > > > > >>> > >> >> >>String,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > val sourcePartition: Int,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > val sourceOffset: Long,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > val key: Array[Byte],
>> >> > > > > > > > > >>> > >> >> >> >> >>> > val value: Array[Byte]) {
>> >> > > > > > > > > >>> > >> >> >> >> >>> > def size = value.length +
>>{if
>> >> (key
>> >> > ==
>> >> > > > > > null) 0
>> >> > > > > > > > > >>>else
>> >> > > > > > > > > >>> > >> >> >>key.length}
>> >> > > > > > > > > >>> > >> >> >> >> >>> > }
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > However, because source
>> >>partition
>> >> and
>> >> > > > offset
>> >> > > > > > is
>> >> > > > > > > > > >>>needed
>> >> > > > > > > > > >>> in
>> >> > > > > > > > > >>> > >> >> >>producer
>> >> > > > > > > > > >>> > >> >> >> >> >>>thread
>> >> > > > > > > > > >>> > >> >> >> >> >>> > for consumer offsets
>> >>bookkeeping,
>> >> the
>> >> > > > record
>> >> > > > > > > > > >>>returned
>> >> > > > > > > > > >>> by
>> >> > > > > > > > > >>> > >> >> >> >> >>> > MirrorMakerMessageHandler
>>needs
>> >>to
>> >> > > > contain
>> >> > > > > > those
>> >> > > > > > > > > >>> > >> >>information.
>> >> > > > > > > > > >>> > >> >> >> >> >>>Therefore
>> >> > > > > > > > > >>> > >> >> >> >> >>> > ProducerRecord does not work
>> >>here.
>> >> We
>> >> > > > could
>> >> > > > > > > > > >>>probably
>> >> > > > > > > > > >>> let
>> >> > > > > > > > > >>> > >> >> >>message
>> >> > > > > > > > > >>> > >> >> >> >> >>>handler
>> >> > > > > > > > > >>> > >> >> >> >> >>> > take ConsumerRecord for both
>> >>input
>> >> > and
>> >> > > > > > output.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >5. Have you guys thought
>>about
>> >> what
>> >> > the
>> >> > > > > > > > > >>>implementation
>> >> > > > > > > > > >>> > >>will
>> >> > > > > > > > > >>> > >> >> >>look
>> >> > > > > > > > > >>> > >> >> >> >> >>>like in
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >terms of threading
>>architecture
>> >> etc
>> >> > with
>> >> > > > > > the new
>> >> > > > > > > > > >>> > >>consumer?
>> >> > > > > > > > > >>> > >> >> >>That
>> >> > > > > > > > > >>> > >> >> >> >>will
>> >> > > > > > > > > >>> > >> >> >> >> >>>be
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >soon so even if we aren't
>> >>starting
>> >> > with
>> >> > > > that
>> >> > > > > > > > let's
>> >> > > > > > > > > >>> make
>> >> > > > > > > > > >>> > >> >>sure
>> >> > > > > > > > > >>> > >> >> >>we
>> >> > > > > > > > > >>> > >> >> >> >>can
>> >> > > > > > > > > >>> > >> >> >> >> >>>get
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >rid
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >of a lot of the current
>>mirror
>> >> maker
>> >> > > > > > accidental
>> >> > > > > > > > > >>> > >>complexity
>> >> > > > > > > > > >>> > >> >>in
>> >> > > > > > > > > >>> > >> >> >> >>terms
>> >> > > > > > > > > >>> > >> >> >> >> >>>of
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >threads and queues when we
>> >>move to
>> >> > that.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > I haven¹t thought about it
>> >> > throughly. The
>> >> > > > > > quick
>> >> > > > > > > > > >>>idea is
>> >> > > > > > > > > >>> > >> >>after
>> >> > > > > > > > > >>> > >> >> >> >> >>>migration
>> >> > > > > > > > > >>> > >> >> >> >> >>> to
>> >> > > > > > > > > >>> > >> >> >> >> >>> > the new consumer, it is
>>probably
>> >> > better
>> >> > > > to
>> >> > > > > > use a
>> >> > > > > > > > > >>>single
>> >> > > > > > > > > >>> > >> >> >>consumer
>> >> > > > > > > > > >>> > >> >> >> >> >>>thread.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > If multithread is needed,
>> >> decoupling
>> >> > > > > > consumption
>> >> > > > > > > > > >>>and
>> >> > > > > > > > > >>> > >> >>processing
>> >> > > > > > > > > >>> > >> >> >> >>might
>> >> > > > > > > > > >>> > >> >> >> >> >>>be
>> >> > > > > > > > > >>> > >> >> >> >> >>> > used. MirrorMaker definitely
>> >>needs
>> >> > to be
>> >> > > > > > changed
>> >> > > > > > > > > >>>after
>> >> > > > > > > > > >>> > >>new
>> >> > > > > > > > > >>> > >> >> >> >>consumer
>> >> > > > > > > > > >>> > >> >> >> >> >>>get
>> >> > > > > > > > > >>> > >> >> >> >> >>> > checked in. I¹ll document the
>> >> changes
>> >> > > > and can
>> >> > > > > > > > > >>>submit
>> >> > > > > > > > > >>> > >>follow
>> >> > > > > > > > > >>> > >> >>up
>> >> > > > > > > > > >>> > >> >> >> >> >>>patches
>> >> > > > > > > > > >>> > >> >> >> >> >>> > after the new consumer is
>> >> available.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >-Jay
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >On Tue, Jan 20, 2015 at 4:31
>> >>PM,
>> >> > > > Jiangjie
>> >> > > > > > Qin
>> >> > > > > > > > > >>> > >> >> >> >> >>><j...@linkedin.com.invalid
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >wrote:
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> Hi Kafka Devs,
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >>
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> We are working on Kafka
>> >>Mirror
>> >> > Maker
>> >> > > > > > > > > >>>enhancement. A
>> >> > > > > > > > > >>> > >>KIP
>> >> > > > > > > > > >>> > >> >>is
>> >> > > > > > > > > >>> > >> >> >> >>posted
>> >> > > > > > > > > >>> > >> >> >> >> >>>to
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> document and discuss on
>>the
>> >> > > > followings:
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> 1. KAFKA-1650: No Data
>>loss
>> >> mirror
>> >> > > > maker
>> >> > > > > > > > change
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> 2. KAFKA-1839: To allow
>> >> partition
>> >> > > > aware
>> >> > > > > > > > mirror.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> 3. KAFKA-1840: To allow
>> >>message
>> >> > > > > > > > filtering/format
>> >> > > > > > > > > >>> > >> >>conversion
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> Feedbacks are welcome.
>>Please
>> >> let
>> >> > us
>> >> > > > know
>> >> > > > > > if
>> >> > > > > > > > you
>> >> > > > > > > > > >>> have
>> >> > > > > > > > > >>> > >>any
>> >> > > > > > > > > >>> > >> >> >> >> >>>questions or
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> concerns.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >>
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> Thanks.
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >>
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >> Jiangjie (Becket) Qin
>> >> > > > > > > > > >>> > >> >> >> >> >>> > >>
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>> >
>> >> > > > > > > > > >>> > >> >> >> >> >>>
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >> >>--
>> >> > > > > > > > > >>> > >> >> >> >> >>Thanks,
>> >> > > > > > > > > >>> > >> >> >> >> >>Neha
>> >> > > > > > > > > >>> > >> >> >> >> >
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >> >>
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >> >>
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >> >>
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >>
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >
>> >> > > > > > > > > >>> > >--
>> >> > > > > > > > > >>> > >Thanks,
>> >> > > > > > > > > >>> > >Neha
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>> >
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >>> --
>> >> > > > > > > > > >>> Thanks,
>> >> > > > > > > > > >>> Neha
>> >> > > > > > > > > >>>
>> >> > > > > > > > > >
>> >> > > > > > > > >
>> >> > > > > > > >
>> >> > > > > > > >
>> >> > > > > > >
>> >> > > > > > >
>> >> > > > > > > --
>> >> > > > > > > Thanks,
>> >> > > > > > > Neha
>> >> > > > > >
>> >> > > > > >
>> >> > > >
>> >> > > >
>> >> >
>> >> >
>> >>
>> >
>> >
>> >
>> >--
>> >Thanks,
>> >Neha
>>
>>
