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https://issues.apache.org/jira/browse/CASSANDRA-3411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis updated CASSANDRA-3411:
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Attachment: 3411-v7.txt
v7 attached.
Cleaned out uses of CLS.length which were mostly incorrect now.
Cleaned up the size tracking code.
Made allocator responsible for recycle/discard decision.
Added enableReserveSegmentCreation "magic flag" to avoid so much churn on
restart/reply.
Switched to pre-append capacity check instead of post-, so no need to mmap more
than a single buffer per segment.
Moved all segment tracking into allocator.
Will create tickets for switching to a txid-based reply, and saving the extra
local copy.
> Pre-allocated, Recycled Commitlog Segment Files
> -----------------------------------------------
>
> Key: CASSANDRA-3411
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3411
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Rick Branson
> Priority: Minor
> Attachments:
> 001-pre-allocated-recycled-commitlog-segment-files-CASSANDRA-3411.patch,
> 003-pre-allocated-recycled-commitlog-segment-files-CASSANDRA-3411.patch,
> 004-pre-allocated-recycled-commitlog-segment-files-CASSANDRA-3411.patch,
> 006-pre-allocated-recycled-commitlog-segment-files-CASSANDRA-3411.patch,
> 3411-cleaned.txt, 3411-v5.txt, 3411-v6-retry.txt, 3411-v7.txt
>
>
> An approach for improving commitlog performance is to pre-allocate the full
> 128MB segment files and reuse them once all the mutations have been flushed.
> Pre-allocation allows writes to be performed without modifying the file size
> metadata, and should (in theory) allow the filesystem to allocate a
> contiguous block of space for the file. Recycling the segment files prevents
> the overhead of pre-allocation from impacting overall performance.
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