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https://issues.apache.org/jira/browse/HADOOP-12593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15034044#comment-15034044
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Sangjin Lee commented on HADOOP-12593:
--------------------------------------

+1 on what [[email protected]] suggested. How about using this to review all 
unsafe uses of volatiles, mainly in the context of using compound operations 
(++, +=, etc.)? [~cmccabe] already flagged one. Volatile 
int/short/byte/double/float are no different in this regard, so they should be 
reviewed too.

> multiple "volatile long" field declarations exist in the Hadoop codebase
> ------------------------------------------------------------------------
>
>                 Key: HADOOP-12593
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12593
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 2.8.0
>            Reporter: Steve Loughran
>            Priority: Minor
>
> If you get your IDE to scan for "volatile long", you find 20-30 entries. 
> Volatile operations on `long` variables are not guaranteed to be atomic, so 
> these usages can be vulnerable to race conditions generating invalid data.
> they need to be replaced by AtomicLong references, except in the specific 
> case that you want performance values for statistics, and are prepared to 
> take the risk



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