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https://issues.apache.org/jira/browse/CASSANDRA-8897?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14543355#comment-14543355
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Stefania commented on CASSANDRA-8897:
-------------------------------------
[~benedict], this is ready for review.
Since my last comment I fixed a few bugs but did not change anything
substantial.
There was indeed a performance degradation when reading the data generated with
the stress profile of CASSANDRA-9240. It was about 600 ops/second slower on my
machine (see 9240_test_results.txt attached) and about 1000 ops/second slower
on cstar_perf (albeit without a restart).
I compared two VisualVM sampler snapshots (attached) and nailed it down to the
screenshot also attached. I then changed Ref.GlobalState to use a concurrent
hash set rather than a concurrent linked queue and the degradation disappeared.
I've also run several cstar_perf tests, with or without the CASSANDRA-9240
profile, with different number of entries and threads. Here are some of them:
http://cstar.datastax.com/tests/id/26987156-fa0c-11e4-94a5-42010af0688f
http://cstar.datastax.com/tests/id/1915bc2a-fa05-11e4-9b87-42010af0688f
http://cstar.datastax.com/tests/id/f7a00bf4-fa09-11e4-9b87-42010af0688f
(the diagrams have some problems and occasionally are missing, not sure why)
And here are the Jenkins results, which look identical to trunk:
http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-8897-testall/lastCompletedBuild/testReport/
http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-8897-dtest/lastCompletedBuild/testReport/
> Remove FileCacheService, instead pooling the buffers
> ----------------------------------------------------
>
> Key: CASSANDRA-8897
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8897
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Stefania
> Fix For: 3.x
>
> Attachments: 9240_test_results.txt,
> snapshot-1431582436640-cpu-backtraces.png,
> snapshot-1431582436640-cpu-calltree-compression-8897.nps,
> snapshot-1431582436640-cpu-calltree-compression-trunk.nps
>
>
> After CASSANDRA-8893, a RAR will be a very lightweight object and will not
> need caching, so we can eliminate this cache entirely. Instead we should have
> a pool of buffers that are page-aligned.
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