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https://issues.apache.org/jira/browse/KAFKA-6626?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16391839#comment-16391839
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Maciej Bryński commented on KAFKA-6626:
---------------------------------------
I think even standard java HashMap can be used.
The only thing I wonder is if we need to use IdentityHashMap (comparing records
by instance, not by equals)
[~ewencp] ?
> Performance bottleneck in Kafka Connect sendRecords
> ---------------------------------------------------
>
> Key: KAFKA-6626
> URL: https://issues.apache.org/jira/browse/KAFKA-6626
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 1.0.0
> Reporter: Maciej Bryński
> Priority: Major
> Attachments: MapPerf.java, image-2018-03-08-08-35-19-247.png
>
>
> Kafka Connect is using IdentityHashMap for storing records.
> [https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerSourceTask.java#L239]
> Unfortunately this solution is very slow (2-4 times slower than normal
> HashMap / HashSet).
> Benchmark result (code in attachment).
> {code:java}
> Identity 4220
> Set 2115
> Map 1941
> Fast Set 2121
> {code}
> Things are even worse when using default GC configuration
> (-server -XX:+UseG1GC -XX:MaxGCPauseMillis=20
> -XX:InitiatingHeapOccupancyPercent=35 -Djava.awt.headless=true)
> {code:java}
> Identity 7885
> Set 2364
> Map 1548
> Fast Set 1520
> {code}
> Java version
> {code:java}
> java version "1.8.0_152"
> Java(TM) SE Runtime Environment (build 1.8.0_152-b16)
> Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)
> {code}
> This problem is greatly slowing Kafka Connect.
> !image-2018-03-08-08-35-19-247.png!
>
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