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https://issues.apache.org/jira/browse/VFS-309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13976849#comment-13976849
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Ryan Boettcher commented on VFS-309:
------------------------------------
I tracked down a problem we were having that appears to be this bug. Turns out
the ThreadLocal class can put more than one value it it's map if the same
object in the same thread adds a value more than once.
What should fix this is in the close() method instead of calling:
threadData.set(null);
the line should instead look like this:
threadData.remove();
The set(Thread) method will only set the "exact" key matching value to null,
leaving all other map entries for the owning Object instance in the Thread
until the thread ends. The remove() method attempts to remove all the entries
for the instance, not just the exact match, though I admit I don't (atm)
entirely understand how it does that.
> ThreadLocal memory leak in DefaultFileContent
> ---------------------------------------------
>
> Key: VFS-309
> URL: https://issues.apache.org/jira/browse/VFS-309
> Project: Commons VFS
> Issue Type: Bug
> Affects Versions: 2.0
> Environment: Tomcat servlet container
> Reporter: jontro
>
> When using commons vfs in a servlet container the ThreadLocal values stored
> will not be released once the request finishes.
> There needs to be a method to clear these values otherwise the data will leak
> into the next request.
> This was detected with tomcat 6.0.26. Upon undeploying an app that uses
> commons vfs tomcat detects the leaks with a huge amount of the following
> messages:
> A web application created a ThreadLocal with key of type
> [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@52fb241d]) and a value
> of type [org.apache.commons.vfs.provider.FileContentThreadData] (value
> [org.apache.commons.vfs.provider.FileContentThreadData@6600167a]) but failed
> to remove it when the web application was stopped. To prevent a memory leak,
> the ThreadLocal has been forcibly removed.
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