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https://issues.apache.org/jira/browse/LANG-334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12518640
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Henri Yandell commented on LANG-334:
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It's great that you've got a fix working in production Jason, the patch seems
good to me.
Any thoughts Michael? I like the simplicity of using synchronizedMap, but the
copy-on-write optimization seems attractive.
And yeah... I've given up trying to replicate this :) I'd need to be using
something like cglib so I could generate new enum subclasses by the thousand
and see if it hits the race condition that way.
> Enum is not thread-safe
> -----------------------
>
> Key: LANG-334
> URL: https://issues.apache.org/jira/browse/LANG-334
> Project: Commons Lang
> Issue Type: Bug
> Reporter: Michael Sclafani
> Fix For: 2.3.1
>
> Attachments: 334.patch, EnumPlay.java
>
>
> Enum uses no synchronization. Even if you assume that instances are only
> declared statically, the cEnumClasses map is global and can be written to
> when a thread triggers static initialization of B.class while some other
> thread is doing getEnumList(A.class). Unsynchronized access of a map
> undergoing mutation is not thread-safe.
> This isn't theoretical. We're seeing ValuedEnum.getEnum(X.class, 0) return
> null after returning the correct value over 100,000 times, and then return
> the correct value again on the next invocation.
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