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From "Tilman Hausherr (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (PDFBOX-4396) Memory leak due to soft reference caching
Date Thu, 06 Dec 2018 09:32:00 GMT

    [ https://issues.apache.org/jira/browse/PDFBOX-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16711189#comment-16711189
] 

Tilman Hausherr edited comment on PDFBOX-4396 at 12/6/18 9:31 AM:
------------------------------------------------------------------

Can you build from source? If yes, open COSStream.java, and add
{code:java}
IOUtils.closeQuietly(randomAccess);{code}
above
{code:java}
randomAccess = scratchFile.createBuffer();{code}
at two places.

My observations that ramdomAccess was not null when an encrypted file is opened, because the
same COSStream is rewritten and it can't be closed before that because this would result in
an exception.


was (Author: tilman):
Can you build from source? If yes, open COSStream.java, and add
{code:java}IOUtils.closeQuietly(randomAccess);{code}
above 
{code:java}randomAccess = scratchFile.createBuffer();{code}
at two places.

> Memory leak due to soft reference caching
> -----------------------------------------
>
>                 Key: PDFBOX-4396
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-4396
>             Project: PDFBox
>          Issue Type: Bug
>    Affects Versions: 2.0.12
>         Environment: JDK10; G1
>            Reporter: Ben Manes
>            Priority: Major
>         Attachments: #2 - memory leak 2.png, #2 - memory leak.png, memory leak 2.png,
memory leak.png
>
>
> In a heap dump, it appears that DefaultResourceCache is retaining 5.3 GB of memory due
to buffered images (via PDImageXObject). I suspect that G1 is not collecting soft references
across all regions before it out-of-memory errors.
> In PDFBOX-4389, I discovered very slow PDDocument#load times due to a JDK10 I/O bug.
Previously I was loading the document to render each page, but this took 1.5 minutes. To work
around that bug I reused the document instance across pages. This seems to have fail because
the pages were cached and not cleared by the GC.
> The DefaultResourceCache does not prune its cache entries when the soft references are
collected. Like WeakHashMap, it should use a ReferenceQueue, poll it on every access, and
prune accordingly.
> Thankfully PDDocument#setResourceCache exists. For now I am going to reset the cache
to a new instance after a page has been rendered. The entries should no longer be reachable
and be GC'd more aggressively. If that doesn't work, I'll either replace the cache (e.g. with
Caffeine) or disable it by setting the instance to null.
> I think the desired fix is to prune the DefaultResourceCache and, ideally, reconsider
usage of soft references (as they tend to be poor in practice). 



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