Re: [xsl] An observation on the performance of fn:transform

["John Lumley john@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 03/07/2020 09:44, Norman Tovey-Walsh ndw@xxxxxxxxxx wrote:
> Hello world,
>
> This isnbt a complaint, or explicitly a request for advice (though Ibm
> always happy for helpful suggestions), just an observation. The workflow
> for processing DocBook documents is roughly this pipeline:
>
> 1. Fixup the logical structure of the document (expand entities and
>     replace entityref attributes with the corresponding fileref
>     attributes).
> 2. Perform XInclude
> 3. Convert DocBook 4.x markup to 5.x markup if the source document
>     appears to be DocBook 4.x (i.e., if its root element is in no
>     namespace)
> 4. Perform transclusion[1]
> 5. Profile
> 6. Resolve annotations
> 7. Resolve XLinks (including external link bases)
>
> ....
> So I coded that up. I now have an *eight* stage pipeline where the last
> stage does the transformation to HTML, cleanup of that HTML, and
> possible chunking. Itbs all still in one stylesheet with modes because I
> havenbt teased it apart yet, itbs just being run with fn:transform
> instead of with a mode in the same stylesheet.
>
> The performance difference is interesting.
>
> Running 1,426 tests through the 8 stage pipeline: 4m19s.
> Running 1,542 tests through the original 7 stages: 50s.
>
> There are fewer tests in the former case because some of my XSpec tests
> just canbt work against the new driver; Ibll have to run two sets of
> tests which is kind of a drag, but I should be running separate tests
> for all the stages anyway so I guess thatbs just the way it is.
>
> The performance difference is presumably because it takes ~0.15s to
> compile the main stylesheet each time. Which is, you know, pretty damned
> fast, but adds up if youbre going to do it thousands of times in a row.
> .....
Perhaps a argument for something akin to fn:compile-transform($options 
as map(*)) as function($options), which does the compilation once and 
returns an exectuable function. Before XSLT3 and xsl:evaluate, Saxon had 
(and still has) something similar for XPath: saxon:expression() and 
saxon:evaluate()


--
*John Lumley* MA PhD CEng FIEE
john@xxxxxxxxxxxx <mailto:john@xxxxxxxxxxxx>
on behalf of Saxonica Ltd