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.kl...@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 <ja...@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 <xiaotao...@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 <ja...@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.kl...@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 <xiaotao...@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.kl...@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 <xiaotao...@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 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
