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https://issues.apache.org/jira/browse/FILEUPLOAD-368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18074183#comment-18074183
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Bruno Antunes commented on FILEUPLOAD-368:
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As a final observation:
* Closing the {{InputStream}} returned by {{FileItem.getInputStream()}} should
be the responsibility of the calling application; this aligns with general Java
best practices for stream handling.
* In this context, explicitly closing streams avoids reliance on
GC/finalization for resource cleanup.
The behavior difference observed between versions appears related to the change
in implementation from {{FileInputStream}} to {{Files.newInputStream(Path)}}
(i.e. {{java.io}} vs {{{}java.nio{}}}). This may affect how unclosed streams
are eventually cleaned up by the JVM.
It may be worth reviewing the Javadoc for {{DiskFileItem.getInputStream()}} to
make the expectation to explicitly close the returned stream more explicit,
possibly aligning with guidance in newer JDK documentation (e.g.
{{{}java.nio.file.Files{}}}).
Also, since finalization has been deprecated for removal in more recent Java
versions, relying on it for resource cleanup is increasingly discouraged.
> 1.6.0 unlike 1.5: brought on an issue where temporary files and descriptors
> were not being freed
> -------------------------------------------------------------------------------------------------
>
> Key: FILEUPLOAD-368
> URL: https://issues.apache.org/jira/browse/FILEUPLOAD-368
> Project: Commons FileUpload
> Issue Type: Bug
> Affects Versions: 1.6.0
> Reporter: David Campbell
> Priority: Major
> Attachments: fileupload-repro-src.zip,
> image-2025-12-02-13-22-04-101.png, image-2025-12-02-13-24-56-498.png
>
>
> An upgrade of commons-fileupload from 1.5 to 1.6.0 brought on a problem on
> high-load servers where uploaded files were not being deleted and the server
> file descriptor utilisation kept growing. On all server instances, file
> resource utilisation kept growing to the point where it was filling /tmp
> completely and then the server instances needed restarting to solve, as file
> space is not reclaimed even on file deletion on Unix servers when file
> descriptors are still open. The same issue occurred on all our server
> instances.
> We had a major production incident as a result.
> Rolled back to 1.5. That fixed the issue, problem completely gone.
> Don't know any further details of the whys at this point.
>
>
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