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From tao xiao <xiaotao...@gmail.com>
Subject Re: New consumer not fetching as quickly as possible
Date Thu, 03 Dec 2015 01:42:41 GMT
It does help with increasing the poll timeout to Long.MAX_VALUE. I got
messages in every poll but just the time between each poll is long. That is
how I discovered it was an network issue btw consumer and broker.  I
believe it will have the same effect as long as I set the poll timeout high
enough, not necessary to be Long.MAX_VALUE.

On Thu, 3 Dec 2015 at 02:04 Guozhang Wang <wangguoz@gmail.com> wrote:

> Thanks for the updates Tao.
>
> Just wanted to make sure that there is no other potential issues when
> consumer and broker are remote, which is also quite common in practice: if
> you increase the timeout value in poll(timeout) to even larger values (say
> two times the average latency in your network) and also set the
> request.timeout.ms config to be large enough as well, does that resolve
> the
> issue even if your consumer is not co-located?
>
> Guozhang
>
> On Wed, Dec 2, 2015 at 12:46 AM, tao xiao <xiaotao183@gmail.com> wrote:
>
> > 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
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
>
>
> --
> -- Guozhang
>

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