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https://issues.apache.org/jira/browse/CASSANDRA-3432?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sylvain Lebresne updated CASSANDRA-3432:
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Attachment: 0001-Break-down-large-long-array.patch
Attaching patch to do this. I suppose in a perfect world we could reuse the
added BigLongArray class in our OpenBitSet implementation, but I didn't
bothered for now (it wouldn't save much).
> Avoid large array allocation for compressed chunk offsets
> ---------------------------------------------------------
>
> Key: CASSANDRA-3432
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3432
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.0.0
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Priority: Minor
> Labels: compression
> Fix For: 1.0.2
>
> Attachments: 0001-Break-down-large-long-array.patch
>
>
> For each compressed file we keep the chunk offsets in memory (a long[]). The
> size of this array is directly proportional to the sstable file and the
> chunk_length_kb used, but say for a 64GB sstable, we're talking ~8MB in
> memory by default.
> Without being absolutely huge, this probably makes the life of the GC harder
> than necessary for the same reasons than CASSANDRA-2466, and this ticket
> proposes the same solution, i.e. to break down those big array into smaller
> ones to ease fragmentation.
> Note that this is only a concern for size tiered compaction. But until
> leveled compaction is battle tested, the default and we know nobody uses size
> tiered anymore, it's probably worth making the optimization.
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