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https://issues.apache.org/jira/browse/PDFBOX-2261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14095841#comment-14095841
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John Hewson commented on PDFBOX-2261:
-------------------------------------
I encountered this issue in PDFBOX-2164 but only added a workaround for a
specific NPE. The recursive approach used by PDField was indeed incorrect, the
PDF spec explains why:
{quote}
For purposes of definition and naming, the fields can be organized
hierarchically and can inherit attributes from their ancestors in the field
hierarchy
{quote}
It seems that the problem with PDFBox's current design is that each node in the
field tree is represented by a PDField, however not every node in the field
tree is really a field, some nodes are just there to organise the tree
structure. One solution would be to have PDAcroForm read the field tree and
have it produce a Map<String, PDField> of named fields, with all of the
inheritance taken into account. Another solution would be to have fields be
aware of their parent in the field tree and look-up appropriate values (this
would preserve the field tree structure between writes), but the parent node
should not be a PDField (!!!) it should be PDNonTerminalField or some similar
new class, the PDF spec is clear on this:
{quote}
A non-terminal field does not logically have a type of its own; it is merely a
container for inheritable attributes that are intended for descendant terminal
fields of any type.
{quote}
> Extremely long hang during getFields() on a few PDF files
> ---------------------------------------------------------
>
> Key: PDFBOX-2261
> URL: https://issues.apache.org/jira/browse/PDFBOX-2261
> Project: PDFBox
> Issue Type: Bug
> Components: AcroForm
> Affects Versions: 1.8.6
> Reporter: Tim Allison
> Assignee: Andreas Lehmkühler
> Priority: Minor
> Fix For: 2.0.0
>
> Attachments: 966679.pdf, RadioButtons.pdf, screenshot-pdfdebugger.png
>
>
> When I run oap.examples.fdf.PrintFields from trunk, the code seems to hang
> during acroForm.getFields(). This is a heavy load hang.
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