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https://issues.apache.org/jira/browse/KAFKA-20917?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kamal Chandraprakash reassigned KAFKA-20917:
--------------------------------------------
Assignee: Xi Wang
> [Java-client] RecordAccumulator.ready performance regression
> ------------------------------------------------------------
>
> Key: KAFKA-20917
> URL: https://issues.apache.org/jira/browse/KAFKA-20917
> Project: Kafka
> Issue Type: Bug
> Components: producer
> Reporter: Xi Wang
> Assignee: Xi Wang
> Priority: Major
> Attachments: Screenshot 2026-07-02 at 1.59.07 PM-1.png, Screenshot
> 2026-07-02 at 1.59.07 PM.png, Screenshot 2026-08-19 at 2.29.20 PM.png,
> Screenshot 2026-08-19 at 2.34.29 PM.png, Screenshot 2026-08-19 at 2.38.46
> PM.png, Screenshot 2026-08-19 at 2.40.28 PM.png, Screenshot 2026-08-19 at
> 2.49.09 PM.png, Screenshot 2026-08-19 at 3.00.26 PM.png, Screenshot
> 2026-08-19 at 9.27.11 PM.png, Screenshot 2026-08-19 at 9.27.35 PM.png,
> Screenshot 2026-08-19 at 9.27.47 PM.png, Screenshot 2026-08-19 at 9.30.29
> PM.png
>
>
> *Produce latency regression after upgrading from 2.8 to 3.9*
> After upgrading producer client from 2.8 to 3.9, we noticed produce latency
> increase, e.g. for ack-all producer, P50 latency increase from 8ms to 13ms.
> (Production set up: 180 brokers, 1000 partitions per broker, replication
> factor is 4).
> !Screenshot 2026-08-19 at 2.49.09 PM.png|width=906,height=228!
> *What changed?*
> The profiling shows RecordAccumulator.ready call is hot. 3.9 introduced
> adaptive partitioning and added more checks and calculations per topic
> partition in RecordAccumulator.ready -> partitionReady method.
> *2.8 client profiling*
> !Screenshot 2026-08-19 at 2.29.20 PM.png|width=906,height=228!
> low cluster.leaderFor call.
> !Screenshot 2026-08-19 at 2.34.29 PM.png|width=906,height=228!
> no metadataSnapshot.leaderEpochFor call (introduced in 3.9)
> *3.9 client profiling* {*}({*}{*}With adaptive partitioning disabled){*}
> heavy cluster.leaderFor and metadataSnapshot.leaderEpochFor calls
> !Screenshot 2026-08-19 at 9.30.29 PM.png|width=906,height=228!
> !Screenshot 2026-08-19 at 2.40.28 PM.png|width=906,height=228!
> !Screenshot 2026-08-19 at 2.38.46 PM.png|width=906,height=228!
> *After Fix*
> Check the fix in the linked PRs.
> {*}3.9 client with fix profiling ({*}{*}With adaptive partitioning
> disabled){*}
> !Screenshot 2026-08-19 at 9.27.11 PM.png|width=906,height=228!
> reduce the cluster.leaderFor call to similar as 2.9 client
> !Screenshot 2026-08-19 at 9.27.35 PM.png|width=906,height=228!
> very low metadataSnapshot.leaderEpochFor call
> !Screenshot 2026-08-19 at 9.27.47 PM.png|width=906,height=228!
> latency reduced to 8ms, similar to 2.8 client latency.
> !Screenshot 2026-08-19 at 3.00.26 PM.png|width=884,height=240!
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