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https://issues.apache.org/jira/browse/CASSANDRA-15388?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17017559#comment-17017559
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Blake Eggleston commented on CASSANDRA-15388:
---------------------------------------------
Yeah I’d really like to quantify the performance changes from these tickets
before committing them. Given the size of the jmh patch though, I’d lean
towards reviewing it separately.
What's the compilation breakage you’re seeing? I haven’t had any issues.
> Add compaction allocation measurement test to support compaction gc
> optimization.
> ----------------------------------------------------------------------------------
>
> Key: CASSANDRA-15388
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15388
> Project: Cassandra
> Issue Type: Sub-task
> Components: Local/Compaction
> Reporter: Blake Eggleston
> Assignee: Blake Eggleston
> Priority: Normal
> Fix For: 4.0
>
>
> This adds a test that is able to quickly and accurately measure the effect of
> potential gc optimizations against a wide range of (synthetic) compaction
> workloads. This test accurately measures allocation rates from 16 workloads
> in less that 2 minutes.
> This test uses google’s {{java-allocation-instrumenter}} agent to measure the
> workloads. Measurements using this agent are very accurate and pretty
> repeatable from run to run, with most variance being negligible (1-2 bytes
> per partition), although workloads with larger but fewer partitions vary a
> bit more (still less that 0.03%).
> The thinking behind this patch is that with compaction, we’re generally
> interested in the memory allocated per partition, since garbage scales more
> or less linearly with the number of partitions compacted. So measuring
> allocation from a small number of partitions that otherwise represent real
> world use cases is a good enough approximation.
> In addition to helping with compaction optimizations, this test could be used
> as a template for future optimization work. This pattern could also be used
> to set allocation limits on workloads/operations and fail CI if the
> allocation behavior changes past some threshold.
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