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https://issues.apache.org/jira/browse/FOP-2937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17729746#comment-17729746
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Peter Radomski edited comment on FOP-2937 at 6/6/23 1:59 PM:
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we have the same issues with FOP 2.8 and large files.
was (Author: pan4o):
we have the same issues with EOP 2.8 and large files.
> [PATCH]Post PDF generation, Soft reference of PDFObject in PDFReference are
> not immediately garbage collected leading to excessive memory usage.
> ------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: FOP-2937
> URL: https://issues.apache.org/jira/browse/FOP-2937
> Project: FOP
> Issue Type: Improvement
> Affects Versions: 2.3, 2.4
> Reporter: Piyush Khandelwal
> Priority: Major
> Attachments: PDFDictionary.patch, pdfreference.patch
>
>
> PDFReference object holds a SoftReference of PDFObject (PDFPage, PDFLabel,
> PDFName etc.).
> If we generate a huge PDF ; *I tried with a PDF having around 150 thousand
> pages with 12 GB of RAM;* lots of these references linger around waiting for
> the garbage collector to collect them.
> But GC wont collect them as long as JVM is able to recover enough memory
> without throwing out of memory.
> Here are few metadata from my testing for further understanding of the issue
> -
> Stats for generating 1 PDF -
> *FO size:* 2.03GB
> *Generated PDF No. of Pages:* Around 150 K
> RAM: 12 GB
> Peak memory that reached while generation - 11.3GB
> Residual memory after forced GC: 9 GB
> The FO mainly contains tabular data with each pages sequence having max of
> 500 rows.
> On analyzing the memory dump; found lots of reference for PDFPage, PDFName
> etc.
> *Question - * Is there any specific reason for using SoftReference in
> PDFReference class instead of WeakReference.
> Testing by changing SoftReference to WeakReference in PDFReference shows
> following improvements without any issue in the generation whatsoever -
> Stats for Generating 5 PDF in parallel -
> *FO size:* 2.03GB
> *Generated PDF No. of Pages:* Around 150 K
> RAM: 12 GB
> Peak memory that reached while generation - 4GB
> Residual memory after forced GC: 300 MB
> So, by changing SoftReference to WeakReference, I was able to generate 5 PDF
> having 150K pages in parallel with max 4GB Ram; without any generation
> issues.
> You can clearly see the performance benefits of changing to WeakReference.
> But as I dont understand the complete internal details of how FOP works, I
> would like to understand if we can target this change and if not what is the
> reason behind using SoftReference?
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