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https://issues.apache.org/jira/browse/PDFBOX-3521?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15558517#comment-15558517
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ASF subversion and git services commented on PDFBOX-3521:
---------------------------------------------------------
Commit 1763931 from [~tilman] in branch 'pdfbox/trunk'
[ https://svn.apache.org/r1763931 ]
PDFBOX-3521: set fontProvider last to avoid concurrency problems, as suggested
by Rob Hinds
> FontProvider not thread safe
> ----------------------------
>
> Key: PDFBOX-3521
> URL: https://issues.apache.org/jira/browse/PDFBOX-3521
> Project: PDFBox
> Issue Type: Bug
> Affects Versions: 2.0.3, 2.1.0
> Reporter: rob hinds
> Priority: Minor
>
> I understand that PDFBox is not yet thread-safe, however, from reading this
> comment on a [similar
> ticket|https://issues.apache.org/jira/browse/PDFBOX-3071?focusedCommentId=14982069&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14982069],
> it seems like the fonts should be thread safe and is something that we want
> to fix. However, I am experiencing an intermittent NullPointerException when
> running multi-threaded unit tests that attempt to read several PDFs at once
> (see details
> [here|http://stackoverflow.com/questions/39831376/pdfbox-npe-loading-fonts].
> Inside FontMapperImpl.java the getProvider and setProvider methods are
> synchronised:
> {code}
> public synchronized void setProvider(FontProvider fontProvider)
> {
> this.fontProvider = fontProvider;
> fontInfoByName = createFontInfoByName(fontProvider.getFontInfo());
> }
> /**
> * Returns the font service provider. Defaults to using
> FileSystemFontProvider.
> */
> public synchronized FontProvider getProvider()
> {
> if (fontProvider == null)
> {
> setProvider(DefaultFontProvider.INSTANCE);
> }
> return fontProvider;
> }
> {code}
> However, the calling code from the findFont() method is not synchronised:
> {code}
> // make sure the font provider is initialized
> if (fontProvider == null)
> {
> getProvider();
> }
> // first try to match the PostScript name
> FontInfo info = getFont(format, postScriptName);
> if (info != null)
> {
> return info.getFont();
> }
> {code}
> As a result, if multiple threads attempt to access this at once, thread A may
> be in the setProvider method and have set fontProvider, but still processing
> the creation of fontInfoByName - so thread B could attempt to access before
> initialised.
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