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From "Yiquan Zhou (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KAFKA-4348) On Mac OS, KafkaConsumer.poll returns 0 when there are still messages on Kafka server
Date Mon, 31 Oct 2016 12:28:59 GMT

    [ https://issues.apache.org/jira/browse/KAFKA-4348?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15622015#comment-15622015
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Yiquan Zhou commented on KAFKA-4348:
------------------------------------

Did you get any "polled 0 records" before polling all the records? Because sometimes the consumer
did poll all the records without interruption like what you got, but only after several seconds
polling 0 record. This happens often right after the start of the server. But if you run the
test for 4-5 more times you might get the same result as I did.

If I set "enable.auto.commit" to true, here is an output that I got:

Mon Oct 31 11:25:39 CET 2016 polled 0 records // first poll
Mon Oct 31 11:25:40 CET 2016 polled 0 records
Mon Oct 31 11:25:41 CET 2016 polled 0 records
Mon Oct 31 11:25:42 CET 2016 polled 0 records
Mon Oct 31 11:25:43 CET 2016 polled 0 records
Mon Oct 31 11:25:43 CET 2016 polled 27171 records
Mon Oct 31 11:25:43 CET 2016 polled 26886 records
Mon Oct 31 11:25:43 CET 2016 polled 26886 records
Mon Oct 31 11:25:44 CET 2016 polled 0 records
Mon Oct 31 11:25:45 CET 2016 polled 0 records
Mon Oct 31 11:25:46 CET 2016 polled 0 records
Mon Oct 31 11:25:47 CET 2016 polled 0 records
Mon Oct 31 11:25:48 CET 2016 polled 0 records
Mon Oct 31 11:25:48 CET 2016 polled 26690 records
Mon Oct 31 11:25:49 CET 2016 polled 26214 records
Mon Oct 31 11:25:49 CET 2016 polled 26214 records
Mon Oct 31 11:25:49 CET 2016 polled 26214 records
Mon Oct 31 11:25:49 CET 2016 polled 13725 records
Mon Oct 31 11:25:50 CET 2016 polled 0 records
Mon Oct 31 11:25:51 CET 2016 polled 0 records
Mon Oct 31 11:25:52 CET 2016 polled 0 records

> On Mac OS, KafkaConsumer.poll returns 0 when there are still messages on Kafka server
> -------------------------------------------------------------------------------------
>
>                 Key: KAFKA-4348
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4348
>             Project: Kafka
>          Issue Type: Bug
>          Components: consumer
>    Affects Versions: 0.9.0.0, 0.9.0.1, 0.10.0.1
>         Environment: Mac OS X EI Capitan, Java 1.8.0_111
>            Reporter: Yiquan Zhou
>              Labels: consumer, mac, polling
>
> Steps to reproduce:
> 1. start the zookeeper and kafka server using the default properties from the distribution:

> $ bin/zookeeper-server-start.sh config/zookeeper.properties
> $ bin/kafka-server-start.sh config/server.properties 
> 2. create a Kafka consumer using the Java API KafkaConsumer.poll(long timeout). It polls
the records from the server every second (timeout set to 1000) and prints the number of records
polled. The code can be found here: https://gist.github.com/yiquanzhou/a94569a2c4ec8992444c83f3c393f596
> 3. use bin/kafka-verifiable-producer.sh to generate some messages: 
> $ bin/kafka-verifiable-producer.sh --topic connect-test --max-messages 200000 --broker-list
localhost:9092
> wait until all 200k messages are generated and sent to the server. 
> 4. Run the consumer Java code. In the output console of the consumer, we can see that
the consumer starts to poll some records, then it polls 0 records for several seconds before
polling some more. like this:
> polled 27160 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 26886 records
> polled 26886 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 0 records
> polled 26701 records
> polled 26214 records
> The bug slows down the consumption of messages a lot. And in our use case, the consumer
wrongly assumes that all messages are read from the topic.
> It is only reproducible on Mac OS X but neither on Linux nor Windows.



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