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https://issues.apache.org/jira/browse/KAFKA-15402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17916037#comment-17916037
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Benoit Delbosc commented on KAFKA-15402:
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Hi David, thanks for your response,
I have just tested a 3.9.0, here is my limited understanding:
The {{ClassicKafkaConsumer}} is closing the {{Fetcher}}, in
{{Fetcher#MaybecloseFetchSession}} a `FetchRequest` is prepared with sessionId
and the {{epoch=FINAL}} metadata to release the session.
The request is sent during the first call to {{ConsumerNetworkClient:poll}}
which return nothing, the Fetcher perform another poll and it takes ~500ms,
this is reported in the {{ClientResponse(latencyMs=508)}}, the time is spent in
`org.apache.kafka.common.network.Selector#select` which is invoking the
nioSelect.
On the broker side I see that the FetchRequest is processed only in few
milliseconds in {{kafka.server.KafkaApis#handleFetchRequest}} and the response
is immediately received by the consumer.
So it's like the FetchRequest is sent by the consumer but it is not flushed or
not readable immediately by the broker but I am not able to prove it.
Let me know if you have any ideas for moving forward.
Note that Kafka is deployed with ZK and consumer properties contain a
{{group.id}} and {{enable.auto.commit=false}}.
> Performance regression on close consumer after upgrading to 3.5.0
> -----------------------------------------------------------------
>
> Key: KAFKA-15402
> URL: https://issues.apache.org/jira/browse/KAFKA-15402
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.5.0, 3.6.0, 3.5.1
> Reporter: Benoit Delbosc
> Assignee: Kirk True
> Priority: Major
> Fix For: 4.1.0
>
> Attachments: image-2023-08-24-18-51-21-720.png,
> image-2023-08-24-18-51-57-435.png, image-2023-08-25-10-50-28-079.png
>
>
> Hi,
> After upgrading to Kafka client version 3.5.0, we have observed a significant
> increase in the duration of our Java unit tests. These unit tests heavily
> rely on the Kafka Admin, Producer, and Consumer API.
> When using Kafka server version 3.4.1, the duration of the unit tests
> increased from 8 seconds (with Kafka client 3.4.1) to 18 seconds (with Kafka
> client 3.5.0).
> Upgrading the Kafka server to 3.5.1 show similar results.
> I have come across the issue KAFKA-15178, which could be the culprit. I will
> attempt to test the proposed patch.
> In the meantime, if you have any ideas that could help identify and address
> the regression, please let me know.
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