[jira] [Commented] (KAFKA-14415) ThreadCache is getting slower with every additional state store

["A. Sophie Blee-Goldman (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-14415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17638119#comment-17638119 ] 

A. Sophie Blee-Goldman commented on KAFKA-14415:
------------------------------------------------

Nice find, I bet the assumption when this was first implemented was that the number of named caches/actual state stores would be pretty low, but the reality is many apps can easily grow to the point of this many sizeBytes() invocations having nontrivial overhead...so yeah, good catch :) 

> ThreadCache is getting slower with every additional state store
> ---------------------------------------------------------------
>
>                 Key: KAFKA-14415
>                 URL: https://issues.apache.org/jira/browse/KAFKA-14415
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>            Reporter: Lucas Brutschy
>            Assignee: Lucas Brutschy
>            Priority: Major
>
> There are a few lines in `ThreadCache` that I think should be optimized. `sizeBytes` is called at least once, and potentially many times in every `put` and is linear in the number of caches (= number of state stores, so typically proportional to number of tasks). That means, with every additional task, every put gets a little slower.Compare the throughput of TIME_ROCKS on trunk (green graph):
> [http://kstreams-benchmark-results.s3-website-us-west-2.amazonaws.com/experiments/stateheavy-3-5-3-4-0-51b7eb7937-jenkins-20221113214104-streamsbench/]
> This is the throughput of TIME_ROCKS is 20% higher when a constant time `sizeBytes` implementation is used:
> [http://kstreams-benchmark-results.s3-website-us-west-2.amazonaws.com/experiments/stateheavy-3-5-LUCASCOMPARE-lucas-20221122140846-streamsbench/]
> The same seems to apply for the MEM backend (initial throughput >8000 instead of 6000), however, I cannot run the same benchmark here because the memory is filled too quickly.
> [http://kstreams-benchmark-results.s3-website-us-west-2.amazonaws.com/experiments/stateheavy-3-5-LUCASSTATE-lucas-20221121231632-streamsbench/]
>  



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