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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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Rick Branson updated CASSANDRA-3411:
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Attachment:
006-pre-allocated-recycled-commitlog-segment-files-CASSANDRA-3411.patch
006 recycles commit log segments after recovery. This holds the segment count
steady across restarts. I removed the initial segment allocation as it seemed
unnecessary after this change.
At this point, there's a deadlock condition that arises if the cap is held
hard. If the cap is hit, in order to make some room in the commit log, a
memtable flush must take place. The memtable flush thread submits a task for
execution on the commit log thread, which is already blocked waiting for the
memtable flush to finish.
> 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
>
>
> 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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