Re: [xml] Performance of DOM interface

[Nick Wellnhofer <nick paradigmashift com>]

Daniel Veillard wrote:
> On Sat, Aug 24, 2002 at 03:13:08PM +0200, wellnhofer aevum de wrote:
>
> > Hi,
> >
> > I'm using libxml and libxslt with Perl to generate dynamic HTML pages 
> > and did some performance testing recently. I created a XML tree from a 
> > Perl data structure using the DOM interface and transform that tree with 
> > XSLT.
> >
> > While the performance of the XSLT transformation is really good, I found 
> > that constructing the DOM tree took about 75% of the running time. So it 
> > takes about three times longer to create the XML source tree than to 
> > parse a stylesheet and apply and output the transformation.
> >
> > Is this behavior normal? I would think creating an XML tree is much 
> > faster than a XSLT transformation.
>
>
>   Well usually when creating the input tree using directly the C parser,
> the parse time (which includes building the DOM tree) is quite smaller than
> the tranformation time itself. So no it's not "normal", though it also 
> depends a lot on the stylesheet used too. You're probably paying the cost
> of going back and forth between the Perl and the C library for each call 
> to DOM entry points.

Yes, that seems to be the only explanation I can think of. The XSLT 
transformation needs about 5 calls to the C library, but the creation of 
the DOM tree requires hundreds of calls of createElement and appendChild.

It might even be faster to generate XML directly in Perl and write it to 
a file or memory buffer and then parse it with libxml again. I think I 
will try that, although it seems like a stupid approach.

The best solution is probably a single Perl XS function that converts a 
whole Perl data structure to a DOM tree in one go.

Nick Wellnhofer