# Hot Thread Wheel Timer

**URL:** <https://discuss.elastic.co/t/hot-thread-wheel-timer/38281>\
**Category:** Elasticsearch\
**Created:** [January 3, 2016, 8:45pm UTC](https://discuss.elastic.co/t/hot-thread-wheel-timer/38281 "2016-01-03T20:45:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![voipoclay](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/voipoclay/32/4372_2.png) [@voipoclay](https://discuss.elastic.co/u/voipoclay)\
**Post date:** [January 3, 2016, 8:45pm UTC](https://discuss.elastic.co/t/hot-thread-wheel-timer/38281/1 "2016-01-03T20:45:00Z")

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Hello all,

I see on and off when I query hot\_threads the following

```
  0.0% (193.2micros out of 500ms) cpu usage by thread 'elasticsearch[CLIENT_02][transport_client_timer][T#1]{Hashed wheel timer #1}'
     10/10 snapshots sharing following 5 elements
       java.lang.Thread.sleep(Native Method)
       org.jboss.netty.util.HashedWheelTimer$Worker.waitForNextTick(HashedWheelTimer.java:445)
       org.jboss.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:364)
       org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
       java.lang.Thread.run(Thread.java:745)

```

It seems like a "notice" and nothing to worry about but was curious if anyone had an insight on that. My client, master and data nodes all seem to show this error on and off.

Thanks,  
Clay

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**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\
**Post date:** [January 3, 2016, 9:06pm UTC](https://discuss.elastic.co/t/hot-thread-wheel-timer/38281/2 "2016-01-03T21:06:33Z")

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The hashed wheel timer is a feature of Netty. ES uses Netty, and Netty sometimes needs to wait for a short time.

For more information see [http://netty.io/wiki/using-as-a-generic-library.html#wiki-h3-12](http://netty.io/wiki/using-as-a-generic-library.html#wiki-h3-12)

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<div class="post-metadata">

**Author:** ![voipoclay](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/voipoclay/32/4372_2.png) [@voipoclay](https://discuss.elastic.co/u/voipoclay)\
**Post date:** [January 3, 2016, 9:07pm UTC](https://discuss.elastic.co/t/hot-thread-wheel-timer/38281/3 "2016-01-03T21:07:59Z")

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> [@jprante](#):
>
> [Netty.docs: Using as a generic library](http://netty.io/wiki/using-as-a-generic-library.html#wiki-h3-12)

Great, thanks!

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 11:27pm UTC](https://discuss.elastic.co/t/hot-thread-wheel-timer/38281/4 "2017-07-05T23:27:23Z")

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