RE: [xsl] problem: recursive templates slowing xalan processor down

["Michael Kay" <mhk@xxxxxxxxx>]

Can't see anything obviously problematic in this. Saxon eats it in about
120ms.

Michael Kay
 

> -----Original Message-----
> From: poppe chris [mailto:pc_poppe@xxxxxxxxxxx] 
> Sent: 10 May 2004 21:48
> To: jeni@xxxxxxxxxxxxxxxx
> Cc: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [xsl] problem: recursive templates slowing xalan 
> processor down
> 
> 
> 
> >Hi Chris,
> >
> > > im having a peculiar problem, ive made a xsl stylesheet 
> that uses a
> > > recursive template. When i use xmlspy to perform the xsl
> > > transformation on a sample xml file everything works 
> fine, but when
> > > i use a xalan processor (org.apache.xalan.xslt.Process) the
> > > recursive template seems to freeze the processing. First I pass
> > > about 15 nodes to the template wich then calls itself 
> with one node
> > > less. and so on. In the beginning it goes fast but after 
> 3 recursive
> > > calls everything slows down and finally looks like its frozen (in
> > > fact i still get some output but only after very long 
> times). Is it
> > > possible that several recursive calls freeze the processor and how
> > > come everything works with the xmlspy debugger??
> >
> >I don't know which processor the XML Spy debugger uses, but it might
> >be that it rewrites (tail) recursive calls into a loop and thus deals
> >with the recursion more efficiently than Xalan.
> >
> >Having said that, Xalan is normally pretty good at that kind of
> >optimisation. (Perhaps you're using an old version? Check which
> >version you're using with system-property('xsl:version').) Seeing a
> >slowdown after only three recursive calls sounds quite severe.
> >
> >Can you show us your recursive template? Perhaps there are some
> >rewrites that could help speed it up...
> >
> Here is a link to the xslt file
> http://www10.brinkster.com/cpoppe/misc/MCTFbit.xsl
> 
> And a link to a sample xml file
> http://www10.brinkster.com/cpoppe/misc/coastlittle.xml
> 
> What this pretty much does is select all the substream 
> elements in the xml 
> file, then read in a length ( part of a list) and take the 
> sum over these 
> values. Ive left a number of things out of the xslt im using 
> but this one 
> still gives the same problems, starting with 15 nodes then 14 
> , 13 and 12 
> (and slowing down and once it gets to 11 or even 10 times 
> take that much 
> time it seems its frozen)
> Im not looking for a completely alternate solution cause ive 
> reduced the 
> sample xmlfile and the xslt a lot. Just an explanation would 
> be helpfull a 
> lot!
> 
> Ive noticed that when i call the calcPart1 template for the 
> first time with 
> .../m:substream[last()] (so i only pass about 5 nodes to the 
> template) 
> everything goes smooth.
> Here is a link to this xslt file
> http://www10.brinkster.com/cpoppe/misc/MCTFbit.xsl
> 
> sincerely,
> Chris
> 
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