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Date: Mon, 12 Dec 2016 14:53:58 +0000 (UTC)
From: "Robert Stupp (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Updated] (CASSANDRA-13034) Move to FastThreadLocalThread
 and FastThreadLocal
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archived-at: Mon, 12 Dec 2016 14:54:00 -0000


     [ https://issues.apache.org/jira/browse/CASSANDRA-13034?page=3Dcom.atl=
assian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Stupp updated CASSANDRA-13034:
-------------------------------------
    Fix Version/s: 3.x
           Status: Patch Available  (was: Open)

||cassandra-3.X|[branch|https://github.com/apache/cassandra/compare/cassand=
ra-3.X...snazy:13034-fast-thread-local-thread-3.X]|[testall|http://cassci.d=
atastax.com/view/Dev/view/snazy/job/snazy-13034-fast-thread-local-thread-3.=
X-testall/lastSuccessfulBuild/]|[dtest|http://cassci.datastax.com/view/Dev/=
view/snazy/job/snazy-13034-fast-thread-local-thread-3.X-dtest/lastSuccessfu=
lBuild/]
||trunk|[branch|https://github.com/apache/cassandra/compare/trunk...snazy:1=
3034-fast-thread-local-thread-trunk]|[testall|http://cassci.datastax.com/vi=
ew/Dev/view/snazy/job/snazy-13034-fast-thread-local-thread-trunk-testall/la=
stSuccessfulBuild/]|[dtest|http://cassci.datastax.com/view/Dev/view/snazy/j=
ob/snazy-13034-fast-thread-local-thread-trunk-dtest/lastSuccessfulBuild/]


> Move to FastThreadLocalThread and FastThreadLocal
> -------------------------------------------------
>
>                 Key: CASSANDRA-13034
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1303=
4
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Robert Stupp
>            Assignee: Robert Stupp
>             Fix For: 3.x
>
>
> (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 ben=
ch tells, that {{FastThreadLocal}} has a runtime of ~2.7ns and {{ThreadLoca=
l}} of ~4.7ns - about 2ns slower (EDIT: subtracted baseline).
> However, looking at the implementations it seems that {{ThreadLocal}}=C2=
=A0has more dependent pointer gets than {{FastThreadLocal}}. This (CPU cach=
e misses) is not reflected in the artificial benchmark below.
> The patch migrates all {{Thread}} instances (except a few in tests) and a=
ll {{ThreadLocal}} instances.
> {code:title=3DFastThreadLocalBench with 4 threads on 4 core CPU}
>      [java] FastThreadLocalBench.baseline                   2  avgt    5 =
 3.023 =C2=B1 0.081  ns/op
>      [java] FastThreadLocalBench.fastThreadLocal            2  avgt    5 =
 5.610 =C2=B1 0.154  ns/op
>      [java] FastThreadLocalBench.fastThreadLocal            4  avgt    5 =
 5.653 =C2=B1 0.042  ns/op
>      [java] FastThreadLocalBench.fastThreadLocal            8  avgt    5 =
 5.763 =C2=B1 0.588  ns/op
>      [java] FastThreadLocalBench.fastThreadLocal           12  avgt    5 =
 5.673 =C2=B1 0.117  ns/op
>      [java] FastThreadLocalBench.threadLocal                2  avgt    5 =
 7.708 =C2=B1 0.723  ns/op
>      [java] FastThreadLocalBench.threadLocal                4  avgt    5 =
 7.604 =C2=B1 0.059  ns/op
>      [java] FastThreadLocalBench.threadLocal                8  avgt    5 =
 7.629 =C2=B1 0.080  ns/op
>      [java] FastThreadLocalBench.threadLocal               12  avgt    5 =
 7.858 =C2=B1 0.483  ns/op
> {code}


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