[jira] [Reopened] (KAFKA-10254) 100% cpu usage by kafkaConsumer poll , when broker can‘t be connect

["John Roesler (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-10254?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

John Roesler reopened KAFKA-10254:
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> 100% cpu usage by kafkaConsumer poll , when broker can‘t be connect 
> --------------------------------------------------------------------
>
>                 Key: KAFKA-10254
>                 URL: https://issues.apache.org/jira/browse/KAFKA-10254
>             Project: Kafka
>          Issue Type: Bug
>          Components: clients
>    Affects Versions: 2.5.0
>            Reporter: xiaotong.wang
>            Priority: Critical
>             Fix For: 2.5.1
>
>         Attachments: image-2020-07-09-19-24-20-604.png
>
>
> steps
> 1、start kafka broker 
> 2、start kafka consumer and subscribe some topic with some kafkaConsumer instance and  call  kafkaConsumer.*poll(Duration.ofMillis(pollTimeout))*   and set auto.commit.enabled=false
> 3、iptables to disable kafka broker  ip  in client vm or shutdown kafka brokers
> 4、cpu go to 100%
>  
> *why?*
>  
>  
> left Vserison :2.3.1
> right Version:2.5.0
>  
> for 2.3.1 kafkaConsumer when kafka  brokers go  down,updateAssignmentMetadataIfNeeded will block x ms and return empty records ,
> !image-2020-07-09-19-24-20-604.png|width=926,height=164!
>  
> for 2.5.0
> private Map<TopicPartition, List<ConsumerRecord<K, V>>> pollForFetches(Timer timer) {
>  *long pollTimeout = coordinator == null ? timer.remainingMs() :*
>  *Math.min(coordinator.timeToNextPoll(timer.currentTimeMs()), timer.remainingMs());*
> i check the source of kafka client ,poll timeout will be change to 0 ms ,when heartbeat timeout ，so  it will call poll without any block ,this will cause cpu go to 100%
>  
>  
>  



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