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https://issues.apache.org/jira/browse/CASSANDRA-21677?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yifan Cai reassigned CASSANDRA-21677:
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Assignee: Stefan Miklosovic (was: Yifan Cai)
> Pool Native Zstd Contexts in Plain ZstdCompressor
> -------------------------------------------------
>
> Key: CASSANDRA-21677
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21677
> Project: Apache Cassandra
> Issue Type: Improvement
> Components: Feature/Compression
> Reporter: Yifan Cai
> Assignee: Stefan Miklosovic
> Priority: Normal
> Attachments: dicts.png, image2.png
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> ZstdCompressorBase.compress()/uncompress() call Zstd's static one-shot
> helpers (Zstd.compress, Zstd.decompress, Zstd.decompressByteArray), each of
> which allocates a native ZSTD_CCtx/ZSTD_DCtx and frees it before returning,
> once per chunk.
> According to CASSANDRA-21672, profiling of the dictionary-compression path
> found roughly 6.5% of node CPU in ZSTD_createCCtx alone at small chunk sizes,
> and the same per-chunk allocation cost applies to plain, non-dictionary Zstd
> compression, which is unaffected by that work. ZstdCompressor should pool a
> reusable ZstdCompressCtx/ZstdDecompressCtx per compressor instance, instead
> of allocating and freeing a native context on every chunk.
> That said, the plain ZstdCompressor is likely less impacted by the per chunk
> allocation, as it typically requires larger chunk size to achieve a good
> compression ratio. The effect of per chunk allocation is more significant for
> small chunks such as 4KiB.
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