poll block question

[xusheng <su...@126.com>]

hi
i find something not sure about poll.
i need some help
my kafka server version is 1.1.0
my kafka client version is 2.3.0
then 128 partition of topic xxx, start 128 thread in one application to consume message.
always run well, but run about a week long , i find there is a consumer hang forever.
strange is only one partition stop consume.
i dump the Thread info :

"ConsumerGroup-58" #302 prio=5 os_prio=0 tid=0x00007f5419626800 nid=0x191d9 runnable [0x00007f540c950000]

   java.lang.Thread.State: RUNNABLE

at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)

at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)

at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)

at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)

- locked <0x00000004461055c8> (a sun.nio.ch.Util$3)

- locked <0x00000004461055b8> (a java.util.Collections$UnmodifiableSet)

- locked <0x0000000449932670> (a sun.nio.ch.EPollSelectorImpl)

at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)

at org.apache.kafka.common.network.Selector.select(Selector.java:794)

at org.apache.kafka.common.network.Selector.poll(Selector.java:467)

at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:539)

at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:262)

at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:233)

at org.apache.kafka.clients.consumer.KafkaConsumer.pollForFetches(KafkaConsumer.java:1281)

at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1225)

at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1201)

Re: poll block question

[Luke Chen <sh...@gmail.com>]

Hi xusheng,
I checked the code stack, and mapped to the kafka code, I can see we either
use Selector#selectNow, or Selector#select(timeoutMs), which should never
hang forever.
If so, I think it might be the `timeoutMS` is too large, and from your code
stack, the timeoutMS came from the Consumer#poll().
Could you reduce the poll timeout to see if that fixes the issue?

Also, I'm checking the code in v3.1, so it might also be possible that
there are some bugs in V2.3 and fixed in future release.

Thank you.
Luke

On Wed, Nov 24, 2021 at 11:12 PM xusheng <su...@126.com> wrote:

> hi
> i find something not sure about poll.
> i need some help
> my kafka server version is 1.1.0
> my kafka client version is 2.3.0
> then 128 partition of topic xxx, start 128 thread in one application to
> consume message.
> always run well, but run about a week long , i find there is a consumer
> hang forever.
> strange is only one partition stop consume.
> i dump the Thread info :
>
> "ConsumerGroup-58" #302 prio=5 os_prio=0 tid=0x00007f5419626800
> nid=0x191d9 runnable [0x00007f540c950000]
>
>    java.lang.Thread.State: RUNNABLE
>
> at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
>
> at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
>
> at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)
>
> at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
>
> - locked <0x00000004461055c8> (a sun.nio.ch.Util$3)
>
> - locked <0x00000004461055b8> (a java.util.Collections$UnmodifiableSet)
>
> - locked <0x0000000449932670> (a sun.nio.ch.EPollSelectorImpl)
>
> at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
>
> at org.apache.kafka.common.network.Selector.select(Selector.java:794)
>
> at org.apache.kafka.common.network.Selector.poll(Selector.java:467)
>
> at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:539)
>
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:262)
>
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:233)
>
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.pollForFetches(KafkaConsumer.java:1281)
>
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1225)
>
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1201)
>
>
>
>
>
>