RE: [xsl] xsl:import performance problems

Subject: RE: [xsl] xsl:import performance problems
From: "Michael Kay" <mike@xxxxxxxxxxxx>
Date: Tue, 29 Jan 2008 16:13:41 -0000
If two modules A and B each import a module C, then it's the same as if they
imported two modules C1 and C2 that happen to have identical content. You're
going to end up with a lot of components (templates, variables etc) existing
more than once with different import precedences. Doesn't sound like a good

Michael Kay

> -----Original Message-----
> From: Ronan Klyne [mailto:ronan.klyne@xxxxxxxxxxx] 
> Sent: 29 January 2008 16:01
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] xsl:import performance problems
> Hello all,
> I have recently found that a particular pattern of imports 
> causes my stylesheet to take a very long time to compile. I 
> really wasn't expecting this to happen, and now I hope that 
> someone can explain to me what is happening...
> I have a set of 20 xsl files, with an extra 'master' xsl file 
> which imports the other files. This works and performs well.
> I ran into problems when I changed this arrangement. In an 
> attempt to break up the set of files so that I could re-use 
> small parts of them elsewhere, I added an import statement to 
> each file so that each imported the files it depended upon. 
> This works out at an average of 3 imports per file, with one 
> particular file being imported in almost every other.
> When I did this, it went from taking 2 seconds to compile to 
> 20 seconds (measured using Saxon's -t switch).
> I can't for the life of me work out why this change would 
> cause such a drastic slowdown. Does anyone have any thoughts 
> or advice on the matter?
> I am using Saxon 6 on Java 1.6, btw.
> 	Ronan
> --
> Ronan Klyne
> Business Collaborator Developer
> Tel: +44 01189 028518
> ronan.klyne@xxxxxxxxxxx

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