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Posted to commits@cassandra.apache.org by "Aleksey Yeschenko (JIRA)" <ji...@apache.org> on 2017/02/05 16:16:42 UTC
[jira] [Updated] (CASSANDRA-13034) Move to FastThreadLocalThread
and FastThreadLocal
[ https://issues.apache.org/jira/browse/CASSANDRA-13034?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Aleksey Yeschenko updated CASSANDRA-13034:
------------------------------------------
Fix Version/s: (was: 3.12)
3.11.0
> Move to FastThreadLocalThread and FastThreadLocal
> -------------------------------------------------
>
> Key: CASSANDRA-13034
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13034
> Project: Cassandra
> Issue Type: Bug
> Reporter: Robert Stupp
> Assignee: Robert Stupp
> Fix For: 3.11.0
>
>
> (Supersedes/includes CASSANDRA-13033 for 3.X & trunk)
> We still use {{ThreadLocal}} in a couple of places, so I was curious how much faster {{FastThreadLocal}} is compared to {{ThreadLocal}}. A micro bench tells, that {{FastThreadLocal}} has a runtime of ~2.7ns and {{ThreadLocal}} of ~4.7ns - about 2ns slower (EDIT: subtracted baseline).
> However, looking at the implementations it seems that {{ThreadLocal}} has more dependent pointer gets than {{FastThreadLocal}}. This (CPU cache misses) is not reflected in the artificial benchmark below.
> The patch migrates all {{Thread}} instances (except a few in tests) and all {{ThreadLocal}} instances.
> {code:title=FastThreadLocalBench with 4 threads on 4 core CPU}
> [java] FastThreadLocalBench.baseline 2 avgt 5 3.023 ± 0.081 ns/op
> [java] FastThreadLocalBench.fastThreadLocal 2 avgt 5 5.610 ± 0.154 ns/op
> [java] FastThreadLocalBench.fastThreadLocal 4 avgt 5 5.653 ± 0.042 ns/op
> [java] FastThreadLocalBench.fastThreadLocal 8 avgt 5 5.763 ± 0.588 ns/op
> [java] FastThreadLocalBench.fastThreadLocal 12 avgt 5 5.673 ± 0.117 ns/op
> [java] FastThreadLocalBench.threadLocal 2 avgt 5 7.708 ± 0.723 ns/op
> [java] FastThreadLocalBench.threadLocal 4 avgt 5 7.604 ± 0.059 ns/op
> [java] FastThreadLocalBench.threadLocal 8 avgt 5 7.629 ± 0.080 ns/op
> [java] FastThreadLocalBench.threadLocal 12 avgt 5 7.858 ± 0.483 ns/op
> {code}
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