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https://issues.apache.org/jira/browse/KAFKA-19804?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18033304#comment-18033304
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Kuan Po Tseng commented on KAFKA-19804:
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Hi [~shivsundar], you're right — I misunderstood the code. I just ran a quick
test to verify your explanation, and it matches what you said. So there’s no
blocking issue here.
I originally noticed this “blocking” behavior during my implementation and
found the test {{testAsyncConsumeUnsubscribeWithoutGroupPermission}} failed. I
did some investigation at that time but ended up drawing the wrong conclusion.
Based on your explanation, it seems that the issue in that test is actually
unrelated. I’ll take another look later.
Thanks again for the correction!
> Improve heartbeat request manager initial HB interval
> ------------------------------------------------------
>
> Key: KAFKA-19804
> URL: https://issues.apache.org/jira/browse/KAFKA-19804
> Project: Kafka
> Issue Type: Task
> Components: clients, consumer
> Reporter: Lianet Magrans
> Assignee: Kuan Po Tseng
> Priority: Major
> Fix For: 4.2.0
>
>
> With KIP-848, consumer HB interval config moved to the broker, so currently,
> the consumer HB request manager starts with a 0ms interval (mainly to send a
> first HB right away after the consumer subscribe + poll). Once a response is
> received, the consumer takes the interval from the response and starts using
> it.
> That 0ms initial interval makes that the HB mgr poll continuously executes
> logic on a tight loop that may not really be needed. It mostly has to wait
> for a response (or a failure).
> Probably worse than this, is the impact on the app thread, given that
> pollTimeout takes into account the maxTimeToWait from the network thread,
> that is directly impacted by the timeToNextHeartbeat
> *
> [https://github.com/apache/kafka/blob/388739f5d847d7a16e389d9891f806547f023476/clients/src/main/java/org/apache/kafka/clients/consumer/internals/AsyncKafkaConsumer.java#L1764-L1766]
> *
> [https://github.com/apache/kafka/blob/781bc7a54b8c4f7c86f0d6bb9ef8399d86d0735e/clients/src/main/java/org/apache/kafka/clients/consumer/internals/AbstractHeartbeatRequestManager.java#L255]
> We should review and consider setting a non-zero initial interval (while we
> wait for the actual interval from the broker). One option to consider would
> be using the request timeout maybe (just a first thought)
> High level goals here would be to:
> * maintain the behaviour of sending a first HB without delay
> * ensure no unneeded activity on the HB mgr poll in the background, in tight
> loop, while we're just waiting for the first HB response with an interval
> * ensure the app thread poll timeout is not affected
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