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From tao xiao <xiaotao...@gmail.com>
Subject Re: New consumer not fetching as quickly as possible
Date Wed, 02 Dec 2015 08:46:14 GMT
It turned out it was due to network latency btw consumer and broker.  Once
I moved the consumer to the same box of broker messages were returned in
every poll.

Thanks for all the helps.

On Wed, 2 Dec 2015 at 15:38 Gerard Klijs <gerard.klijs@dizzit.com> wrote:

> Another possible reason witch comes to me mind is that you have multiple
> consumer threads, but not the partitions/brokers to support them. When I'm
> running my tool on multiple threads I get a lot of time-outs. When I only
> use one consumer thread I get them only at the start and the end.
>
> On Wed, Dec 2, 2015 at 5:43 AM Jason Gustafson <jason@confluent.io> wrote:
>
> > There is some initial overhead before data can be fetched. For example,
> the
> > group has to be joined and topic metadata has to be fetched. Do you see
> > unexpected empty fetches beyond the first 10 polls?
> >
> > Thanks,
> > Jason
> >
> > On Tue, Dec 1, 2015 at 7:43 PM, tao xiao <xiaotao183@gmail.com> wrote:
> >
> > > Hi Jason,
> > >
> > > You are correct. I initially produced 10000 messages in Kafka before I
> > > started up my consumer with auto.offset.reset=earliest. But like I said
> > the
> > > majority number of first 10 polls returned 0 message and the lag
> remained
> > > above 0 which means I still have enough messages to consume.  BTW I
> > commit
> > > offset manually so the lag should accurately reflect how many messages
> > > remaining.
> > >
> > > I will turn on debug logging and test again.
> > >
> > > On Wed, 2 Dec 2015 at 07:17 Jason Gustafson <jason@confluent.io>
> wrote:
> > >
> > > > Hey Tao, other than high latency between the brokers and the
> consumer,
> > > I'm
> > > > not sure what would cause this. Can you turn on debug logging and run
> > > > again? I'm looking for any connection problems or metadata/fetch
> > request
> > > > errors. And I have to ask a dumb question, how do you know that more
> > > > messages are available? Are you monitoring the consumer's lag?
> > > >
> > > > -Jason
> > > >
> > > > On Tue, Dec 1, 2015 at 10:07 AM, Gerard Klijs <
> gerard.klijs@dizzit.com
> > >
> > > > wrote:
> > > >
> > > > > Thanks Tao, it worked.
> > > > > I also played around with my test setting trying to replicate your
> > > > results,
> > > > > using default settings. But als long as the poll timeout is set to
> > > 100ms
> > > > or
> > > > > larger the only time-out I get are near the start and near the end
> > > (when
> > > > > indeed there is nothing to consume). This is with a producer
> putting
> > > out
> > > > > 1000 messages a second. Maybe the load of the producer your using
> is
> > > not
> > > > > constant? Maybe you could run a test with the
> > > > > org.apache.kafka.tools.ProducerPerformance class to see if it
> makes a
> > > > > difference?
> > > > >
> > > > > On Tue, Dec 1, 2015 at 11:35 AM tao xiao <xiaotao183@gmail.com>
> > wrote:
> > > > >
> > > > > > Gerard,
> > > > > >
> > > > > > In your case I think you can set fetch.min.bytes=1 so that the
> > server
> > > > > will
> > > > > > answer the fetch request as soon as a single byte of data is
> > > available
> > > > > > instead of accumulating enough messages.
> > > > > >
> > > > > > But in my case is I have plenty of messages in broker and I
am
> sure
> > > the
> > > > > > size of total message are much larger than the default setting
> > which
> > > is
> > > > > > 1024 bytes but still the consumer doesn't return messages for
> every
> > > > poll.
> > > > > >
> > > > > >
> > > > > > On Tue, 1 Dec 2015 at 18:29 Gerard Klijs <
> gerard.klijs@dizzit.com>
> > > > > wrote:
> > > > > >
> > > > > > > I was experimenting with the timeout setting, but as long
as
> > > messages
> > > > > are
> > > > > > > produced and the consumer(s) keep polling I saw little
> > difference.
> > > I
> > > > > did
> > > > > > > see for example that when producing only 1 message a second,
> > still
> > > it
> > > > > > > sometimes wait to get three messages. So I also would like
to
> > know
> > > if
> > > > > > there
> > > > > > > is a faster way.
> > > > > > >
> > > > > > > On Tue, Dec 1, 2015 at 10:35 AM tao xiao <xiaotao183@gmail.com
> >
> > > > wrote:
> > > > > > >
> > > > > > > > Hi team,
> > > > > > > >
> > > > > > > > I am using the new consumer with broker version 0.9.0.
I
> notice
> > > > that
> > > > > > > > poll(time) occasionally returns 0 message even though
I have
> > > enough
> > > > > > > > messages in broker. The rate of returning 0 message
is quite
> > high
> > > > > like
> > > > > > 4
> > > > > > > > out of 5 polls return 0 message. It doesn't help by
> increasing
> > > the
> > > > > poll
> > > > > > > > timeout from 300ms to 1 second. are there any configurations
> > > that I
> > > > > can
> > > > > > > > tune to fetch  data as quickly as possible?
> > > > > > > >
> > > > > > > > Both consumer and broker configs are default
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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