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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2013/12/05 20:33:35 UTC
[jira] [Updated] (CASSANDRA-3578) Multithreaded commitlog
[ https://issues.apache.org/jira/browse/CASSANDRA-3578?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jonathan Ellis updated CASSANDRA-3578:
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Attachment: 3578-logging-v2.txt
I'm not really sure what users should take away from the % numbers. v2 simplifies to just a count and average lag duration.
> Multithreaded commitlog
> -----------------------
>
> Key: CASSANDRA-3578
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3578
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Assignee: Benedict
> Priority: Minor
> Labels: performance
> Fix For: 2.1
>
> Attachments: 0001-CASSANDRA-3578.patch, 3578-logging-v2.txt, ComitlogStress.java, Current-CL.png, Multi-Threded-CL.png, TestEA.java, latency.svg, oprate.svg, parallel_commit_log_2.patch
>
>
> Brian Aker pointed out a while ago that allowing multiple threads to modify the commitlog simultaneously (reserving space for each with a CAS first, the way we do in the SlabAllocator.Region.allocate) can improve performance, since you're not bottlenecking on a single thread to do all the copying and CRC computation.
> Now that we use mmap'd CommitLog segments (CASSANDRA-3411) this becomes doable.
> (moved from CASSANDRA-622, which was getting a bit muddled.)
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