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https://issues.apache.org/jira/browse/XERCESJ-970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Simmons updated XERCESJ-970:
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Attachment: comments.txt
Actually the buffer doesn't double in size when you append a char array, it
grows linearly. This char array method is what's used when parsing comments.
The attached patch includes a test harness and fix.
On my box without the fix it takes over 8 seconds to parse a large comment,
with the fix 1/8 second.
We have a real life example where a client commented out 40k lines of XML with
a similar resulting performance hit.
> Large comments are extremely slow to parse
> ------------------------------------------
>
> Key: XERCESJ-970
> URL: https://issues.apache.org/jira/browse/XERCESJ-970
> Project: Xerces2-J
> Issue Type: Bug
> Components: XNI
> Affects Versions: 2.2.0, 2.2.1, 2.3.0, 2.4.0, 2.5.0, 2.6.0, 2.6.1, 2.6.2
> Environment: Windows XP running Java 1.4.2
> Reporter: Sean Griffin
> Priority: Minor
> Attachments: comments.txt
>
>
> Very large comments drastically increase the parsing time for both SAX and
> DOM implementations. Running the sax.Counter and dom.Counter samples with a
> 410KB file where the entire thing is uncommented results in parse times in
> the 100ms to 300ms range. However, if I comment out 95% of the file and run
> the same samples the parse times jump to between 40 and 50 seconds. I ran
> the same samples using the Aelfred parser shipped with Saxon 7.9 and, while
> the file with the large comment was slower than without the comment, it
> jumped by only 100ms or so.
> I briefly compared the code between the two parsers, and they don't look
> significantly different when it comes to handling comments. The only main
> difference I noticed was around low/high byte character checks. I suspect it
> is an inefficiency in the XMLStringBuffer class, but I'm not seeing anything.
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