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https://issues.apache.org/jira/browse/SPARK-26817?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun updated SPARK-26817:
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    Comment: was deleted

(was: A user of thincrs has selected this issue. Deadline: Thu, Feb 14, 2019 
6:03 PM)

> Use System.nanoTime to measure time intervals
> ---------------------------------------------
>
>                 Key: SPARK-26817
>                 URL: https://issues.apache.org/jira/browse/SPARK-26817
>             Project: Spark
>          Issue Type: Improvement
>          Components: Spark Core
>    Affects Versions: 2.4.0
>            Reporter: Maxim Gekk
>            Priority: Minor
>
> Replace System.currentTimeMillis() by System.nanoTime in time intervals 
> measurements. System.currentTimeMillis() returns current wallclock time and 
> will follow changes to the system clock. Thus, negative wallclock adjustments 
> can cause timeouts to "hang" for a long time (until wallclock time has caught 
> up to its previous value again). This can happen when ntpd does a "step" 
> after the network has been disconnected for some time. The most canonical 
> example is during system bootup when DHCP takes longer than usual. This can 
> lead to failures that are really hard to understand/reproduce. 
> System.nanoTime() is guaranteed to be monotonically increasing irrespective 
> of wallclock changes.
>  
> https://github.com/databricks/scala-style-guide#prefer-nanotime-over-currenttimemillis



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