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https://issues.apache.org/jira/browse/PDFBOX-845?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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John Hewson resolved PDFBOX-845.
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Resolution: Cannot Reproduce
I'm closing this as "cannot reproduce" due to the age of this bug, and the fact
that PDFBox doesn't contain any synchronised code, which raises questions about
JVM bugs, etc.
If somebody has a code sample which can reproduce this with the current 2.0
trunk, then please re-open this issue and attach it.
> Lockup in PDDocument.load() --> PDFParser.parseObject() with 6 threads
> ----------------------------------------------------------------------
>
> Key: PDFBOX-845
> URL: https://issues.apache.org/jira/browse/PDFBOX-845
> Project: PDFBox
> Issue Type: Bug
> Components: Parsing
> Affects Versions: 1.2.1
> Environment: Linux lxdev01 2.6.32-24-generic #42-Ubuntu SMP Fri Aug
> 20 14:24:04 UTC 2010 i686 GNU/Linux
> java version "1.6.0_20"
> Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
> Java HotSpot(TM) Server VM (build 16.3-b01, mixed mode)
> testng 5.11
> running under maven-surefire plugin v2.5 with parallel=methods and
> threadCount=6
> Reporter: Larry West
> Priority: Critical
> Attachments: pddocument-load-lockup.stack
>
> Original Estimate: 32h
> Remaining Estimate: 32h
>
> This is a TestNG unit test suite, with each test loading a different PDF via
> PDDocument.load(). I just switched TestNG to parallel=methods (had been
> serial) and it locked up first time. "jstack -l" output will be attached,
> but I'm putting the pdfbox portions here (just below).
> In looking at the code, it's not clear what's being waited on, except that
> four of the threads are stuck in BaseParser.parseDirObject(), apparently
> waiting on the (synchronized) toString() method of a [local] StringBuffer.
> (StringBuffer is used in BaseParser.java where a StringBuilder is clearly
> preferable -- this is probably true for every local instance of a
> StringBuffer.)
> I don't know why that would cause the thread to sit waiting, though (JVM
> problem? 1.6.0_20 on Linux), and the other two threads appear to be waiting
> on COSObjectKey.getNumber() [perhaps], and I see no synchronized objects or
> methods there.
> Finding the cause of the lockup would be preferable, but replacing
> StringBuffer with StringBuilder whereever they are used locally (possibly
> including any private non-static members) would be an improvement in
> performance if nothing else.
> Threads 1, 2, 4, & 6:
> at
> org.apache.pdfbox.pdfparser.BaseParser.parseDirObject(BaseParser.java:1013)
> at
> org.apache.pdfbox.pdfparser.BaseParser.parseCOSDictionaryValue(BaseParser.java:157)
> at
> org.apache.pdfbox.pdfparser.BaseParser.parseCOSDictionary(BaseParser.java:233)
> at
> org.apache.pdfbox.pdfparser.BaseParser.parseDirObject(BaseParser.java:929)
> at org.apache.pdfbox.pdfparser.PDFParser.parseObject(PDFParser.java:519)
> at org.apache.pdfbox.pdfparser.PDFParser.parse(PDFParser.java:179)
> Threads 3 & 5:
> at
> org.apache.pdfbox.cos.COSDocument.getObjectFromPool(COSDocument.java:481)
> at org.apache.pdfbox.pdfparser.PDFParser.parseObject(PDFParser.java:540)
> at org.apache.pdfbox.pdfparser.PDFParser.parse(PDFParser.java:179)
> I should add: these same tests, using the same files, have run literally
> hundreds of times on various machines (Windows, Mac, Linux) using PDFBox
> 1.2.1 without any lockup.
> Clearly I can back off parallelizing my tests for now, but there is no
> obvious reason why PDDocument.load() can't be called in parallel, and so it
> concerns me that this will be a real problem.
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