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From "Marek Zawirski (JIRA)" <>
Subject [jira] Commented: (VFS-253) AbstractFileObject: wrong synchronization of content-related code
Date Thu, 07 May 2009 16:03:30 GMT


Marek Zawirski commented on VFS-253:

I tried to patch it, but I gave up, at least for now, as semantic of this class in context
{{AbstractFileObject#close()}} is unclear for me.

After further close-up at {{DefaultFileContent}}  it appears it may have more synchronization
issues that may lead to race conditions:
- unsynchronized single-read or single-write of non-volatile fields (like {{resetAttributes}})
- lack of double-checked locks (like in {{getAttributes()}}) or other issues causing unnecessary
performing some operations twice
- concurrent access to attrs map
- possibly others...

> AbstractFileObject: wrong synchronization of content-related code
> -----------------------------------------------------------------
>                 Key: VFS-253
>                 URL:
>             Project: Commons VFS
>          Issue Type: Bug
>    Affects Versions: 2.0
>            Reporter: Marek Zawirski
> Creating content through {{AbstractFileObject#getContent()}} and {{DefaultFileContent}}
itself seem to be synchronized, but closing the content by {{AbstractFileObject#close()}}
and checking whether it is open, by {{AbstractFileObject#isContentOpen()}} are NOT synchronized.
> Both these methods miss some lock-object. For {{close()}} it may result in severe race
condition in case of {{FileObject}} shared across more than one thread.
> BTW, thead-safeness of important VFS classes/interfaces like {{FileObject}} is not documented
in javadoc.

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