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https://issues.apache.org/jira/browse/CASSANDRA-16072?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17183127#comment-17183127
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Michael Semb Wever edited comment on CASSANDRA-16072 at 8/24/20, 10:02 AM:
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Patches
-
[3.11|https://github.com/apache/cassandra/compare/cassandra-3.11...thelastpickle:mck/cassandra-3.11_cas_improvements]
-
[trunk|https://github.com/apache/cassandra/compare/trunk...thelastpickle:mck/trunk_cas_improvements]
(will update with CI later today)
was (Author: michaelsembwever):
Patches
-
[3.11|https://github.com/apache/cassandra/compare/cassandra-3.11...thelastpickle:mck/cassandra-3.11_cas_improvements]
-
[trunk|https://github.com/apache/cassandra/compare/trunk...thelastpickle:mck/trunk_cas_improvements
(will update with CI later today)
> Reduce thread contention in CommitLogSegment and HintsBuffer by rewriting CAS
> loops to atomic adds
> --------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-16072
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16072
> Project: Cassandra
> Issue Type: Improvement
> Components: Consistency/Hints, Local/Commit Log
> Reporter: Michael Semb Wever
> Assignee: Michael Semb Wever
> Priority: Normal
> Fix For: 3.11.x, 4.0-beta
>
>
> Follow up to CASSANDRA-15922
> Both CommitLogSegment and HintsBuffer use AtomicIntegers for the current
> offset when allocating. Like in CASSANDRA\-15922 the loops on
> {{.compareAndSet(..)}} can be replaced with atomic adds using the {{.
> getAndAdd(..)}} method.
> In highly contended environments the CAS failures can be high, starving
> writes in a running Cassandra node. On the same cluster CASSANDRA\-15922 was
> found, after CASSANDRA\-15922's fix was deployed, there was still problems
> around commit log flushing and hints. No flamegraph was collected that
> demonstrated the thread contention as clearly as was found in
> CASSANDRA\-15922, but the performance fix proposed here hopefully is obvious
> enough.
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