Re: [xml] xmlTextReader performance question

On Wed, Jan 17, 2007 at 01:21:19PM -0500, Russell Mok wrote:
I am switching to the reader API from XPath to improve 

  Hum, you compare apples to oranges here I hope you're
aware of that.

A lot of time is spent on processing a huge 
list of similar elements. The attributes of each element are 
what I am after. I notice a significant performance gain 
when I replace xmlTextReaderGetAttribute to a sequence of


probably because there are very few possible values for the 
attributes in all my test documents. I understand it is very 
difficult to answer performance tradeoff questions and that 
could change in the future. I just hope someone can tell me 
a bit more what is happening here. Is there a hash/set for 
these 'const xmlChar *' strings so that allocation and 
deallocation are minimized?

 depends, for strings coming from markup, yes. For strings
coming fron content, no, because content is not bounded
and we don't want to stick to constant size.

I have a separate question. Can I save some 
allocation/deallocation if I use xmlReaderForMemory instead 
of xmlReaderForFile? I am thinking of memory mapping the 
whole file.

  I guess that will be lost in the mass of existing allocations
needed for the reader.


Red Hat Virtualization group
Daniel Veillard      | virtualization library
veillard redhat com  | libxml GNOME XML XSLT toolkit | Rpmfind RPM search engine

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