Re: [xsl] Slow XSLT

Hi Jordan,

A lot has already been said and many suggestions have already been made 
in this thread to speed up the processing of your stylesheet, but since 
your stylesheet is rather straightforward I doubt if any of the 
suggestions really speed up the processing.
I'm afraid I haven't followed the discussion closely enough to know how 
you actually invoke the transformation in the browsers. If you use an 
XML with a PI, it will be hard to do good measurements of where the 
culprit may lie. If you use JavaScript + XMLHttpRequest (XHR) to load 
your XML and the XSLT (or when you do the same but by using Sarissa), it 
can be a bit easier to find out what the real transformation time is.
The problem I have with you 7 seconds is that I have only seen this kind 
of slow performance in rare corner cases that often have no place in a 
browser. These are, for instance, really large input documents or 
complex string handling through recursion. A typical time of, say, 10K 
input documents should rather be between 50 - 200 ms (of course, this is 
too rough to make a good guess). As a comparison, I have co-developed a 
rather large RIA platform on which a typical page build-up requires 
about 18 transformations (some are cyclic) which altogether take about 
150ms. Of course, I reuse stylesheets, compiled stylesheets and XML 
sources as much as I can to achieve this performance. Rendering the 
complex pages takes far more time, unfortunately.
To measure the real transformation time you'll have to put timers after 
the stylesheet compilation and the moment the XML source has been 
received in full. Then, after the stylesheet transformation has 
completed, you stop the timer. This is your transformation time. This, 
however, will not work if you have external entities, external DTDs, 
xsl:import/include statements or document () calls, because the latency 
involved in downloading and parsing these external sources are hard to 
differentiate from you overall process. Best you can do is remove all 
external references from XML and XSLT.
If you still find yourself looking at a 7 seconds delay, I bet you hit 
some weird bug (though it is fairly odd to find that in both 
TransformIIX and MSXML). You can use the commandline version of MSXML 
3.0 to find out what time the actual transformation takes (which will be 
a better comparison then using Saxon, for Saxon is a completely 
different processor).
In addition to all this: have you watched your processor and memory 
occupation during transformation time? Does the browser lock up, or is 
it still responsive? (IE usually locks up during the transformation 
phase, if it takes long, it is long locked up). Is the processor at 100% 
(if you have multiple cores, divide that number by the number of cores), 
is the memory vastly increasing? Running the transformation multiple 
times, how long does that take (when a second pass is significantly 
faster, then external sources might be the culprit).
If you do take the downloadtime in your measurements (which you 
shouldn't) or the XML-to-string-to-DOM conversion (which is required in 
MS IE to get from a freethreaded DOM object to a normally threaded DOM 
object which can be parsed in the browser) then you may look at 
significantly higher times. On a side note: in both IE and FF some DOM 
operations are much slower then adding stringized XML as the innerHTML 
of some element instead (may differ a factor of 20 according to some 
reports!).
Last q.: can you put your page and your XML/XSLT online on a working web 
page? Maybe we can see something that otherwise wouldn't easily be seen 
by only talking abstractly about it.
Cheers,
-- Abel Braaksma


Cleyton Jordan wrote:
> Hi Tony,
>
> Thanks for your input.
>
> I am trying to digest all the suggestions you made in
> your post. Thanks.
>
> Meanwhile I have made some changes to my mrs template
> as per your suggestion. I did not quite understand the
> bit you said I do not need to use the 'if' statement.
> Can you please elaborate on that?
>
> This is what I have changed:
>
> <xsl:template match="Msr">
>     <xsl:variable name="numberVal" select="@val"/>
>     <xsl:choose>
>       <!--<xsl:when test="string(number(@val))
> ='NaN'">-->
>       <xsl:when test="not(number($numberVal))">
>         <td align="left" style="overflow:none">
>           <nobr>
>             <div style="width:80px;overflow:none">
>               <xsl:value-of select="$numberVal"/>
>             </div>
>           </nobr>
>         </td>
>       </xsl:when>
>       <xsl:otherwise>
>         <td align="right" style="overflow:none">
>           <nobr>
>             <div style="width:80px;overflow:none">
>               <xsl:variable name="style"
> select="@class"/>
>               <xsl:if test="$numberVal != ''">
>                 <xsl:choose>
>                   <xsl:when test="$style='num1'">
>                     <xsl:value-of
> select="format-number($numberVal,'###,')"/>
>                   </xsl:when>
>                   <xsl:when test="$style='cur1'">
>                     <xsl:value-of
> select="format-number($numberVal,$ltCurFormat)"/>
>                   </xsl:when>
>                   <!--<xsl:when test="$numberVal =
> '-1' or $numberVal = '0'">
>                     <xsl:text
> xml:space="preserve">-</xsl:text>
>                   </xsl:when>-->
>                   <xsl:when test="$numberVal = '-1' or
> $numberVal = '0'">
>                     <xsl:text
> xml:space="preserve">-</xsl:text>
>                   </xsl:when>
>                   <xsl:when test="$style='percent'">
>                     <xsl:value-of
> select="format-number($numberVal * 100,'0.00')"/>
>                     <xsl:text>%</xsl:text>
>                   </xsl:when>
>                   <xsl:otherwise>
>                     <xsl:value-of
> select="format-number($numberVal,$ltNumFormat)"/>
>                   </xsl:otherwise>
>                 </xsl:choose>
>               </xsl:if>
>               <xsl:if test="$numberVal = ''">
>                 <xsl:text
> xml:space="preserve">-</xsl:text>
>               </xsl:if>
>             </div>
>           </nobr>
>         </td>
>       </xsl:otherwise>
>     </xsl:choose>
>   </xsl:template>
>
> --- Tony Graham <Tony(_dot_)Graham(_at_)MenteithConsulting(_dot_)com>
> wrote:
>
>   
> > On Thu, Mar 13 2008 16:33:02 +0000,
> > cleytonjordan(_at_)yahoo(_dot_)co(_dot_)uk wrote:
> >     
> > > Here is the latest working XSLT however it is slow
> > > _________________________________________________
> > >
> > > <?xml version="1.0" encoding="UTF-8"?>
> > > <xsl:stylesheet version="1.0"
> > > xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
> > >   <xsl:strip-space elements="*"/>
> > >
> > >   <xsl:decimal-format name="fd1"
> > >       
> > decimal-separator="."
> >     
> > > grouping-separator="," NaN=" \"/>
> > >       
> > fd1 appears to be unused.
> >
> >     
> > >   <xsl:param name="axisHeads" select="'false'"/>
> > >   <xsl:param name="sortCol" select="'0'"/>
> > >   <xsl:param name="sortCell" select="'0'"/>
> > >   <xsl:param name="dataType" select="'text'"/>
> > >   <xsl:param name="sortOrder"
> > >       
> > select="'ascending'"/>
> >     
> > >   <xsl:param name="ltCurFormat"
> > > select="'$##,###.00'"/>
> > >   <xsl:param name="ltNumFormat"
> > > select="'###,.00'"/>
> > >       
> > Saxon 6.5.5 objects to this number format.
> >
> >     
> > >   <xsl:param name="heading"/>
> > >   <xsl:param name="height" select="'500'"/>
> > >   <xsl:param name="width" select="'880'"/>
> > >   <xsl:param name="id" select="'audit'"/>
> > >
> > >
> > >   <xsl:template match="Report">
> > >     <html>
> > >       <head>
> > >         <title>report</title>
> > >       </head>
> > >       <body>
> > >         <table border="1">
> > >           <xsl:apply-templates/>
> > >         </table>
> > >       </body>
> > >     </html>
> > >   </xsl:template>
> > >   
> > >   <xsl:template match="Row">
> > >     <tr>
> > >       <xsl:apply-templates/>
> > >     </tr>
> > >   </xsl:template>
> > >   
> > >   <xsl:template match="Msr">
> > >       
> > Considering the number of times @val is used, you
> > could make a variable
> > for it before this xsl:choose instead of making
> > $numberVal below.
> >
> >     
> > >     <xsl:choose>
> > >       <xsl:when test="string(number(@val))
> > >       
> > ='NaN'">
> >
> > boolean(NaN) is not true [1], so you could do
> > "not(number(@val))".
> >
> > Considering that your most common NaN case appears
> > to be 'val=""', it
> > might be quicker to do "$val = '' or
> > not(number($val)".
> >
> > Judging by your sample data, the NaN is the most
> > common case.  If it
> > isn't, you could try reversing the sense of the test
> > and exchanging the
> > contents of the xsl:when and the xsl:otherwise to
> > see if that made any
> > difference.
> >
> > If you had the option, it might be better to just
> > omit @val from your
> > XML when it doesn't have a useful value.  Checking
> > for the existence of
> > an attribute has to be quicker than checking that
> > the attribute's value
> > is not a number.
> >
> >     
> > >         <td align="left" style="overflow:none">
> > >           <nobr>
> > >             <div style="width:80px;overflow:none">
> > >               <xsl:value-of select="@val"/>
> > >             </div>
> > >           </nobr>
> > >         </td>
> > >       </xsl:when>
> > >       <xsl:otherwise>
> > >         <td align="right" style="overflow:none">
> > >           <nobr>
> > >             <div style="width:80px;overflow:none">
> > >               <xsl:variable name="numberVal"
> > > select="@val"/>
> > >               <xsl:variable name="style"
> > > select="@class"/>
> > >       
> > This xsl:if and xslchoose could be one xsl:choose.
> >
> > You could experiment with putting the most
> > frequently true xsl:when
> > cases first in the xsl:choose to see if that makes
> > any difference to the
> > speed.
> >
> >     
> > >               <xsl:if test="$numberVal != ''">
> > >                 <xsl:choose>
> > >                   <xsl:when test="$numberVal =
> > >       
> > '-1' or
> >     
> > > $numberVal = '0'">
> > >                     <xsl:text
> > > xml:space="preserve">-</xsl:text>
> > >                   </xsl:when>
> > >       
> > This xsl:when is identical to the one above:
> >
> >     
> > >                   <xsl:when test="$numberVal =
> > >       
> > '-1' or
> >     
> > > $numberVal = '0'">
> > >                     <xsl:text
> > > xml:space="preserve">-</xsl:text>
> > >                   </xsl:when>
> > >                   <xsl:when
> > >       
> > test="$style='wholeNum'">
> >     
> > >                     <xsl:value-of
> > > select="format-number($numberVal,'###,')"/>
> > >                   </xsl:when>
> > >                   <xsl:when
> > >       
> > test="$style='currency'">
> >     
> > >                     <xsl:value-of
> > > select="format-number($numberVal,$ltCurFormat)"/>
> > >                   </xsl:when>
> > >                   <xsl:when
> > >       
> > test="$style='percent'">
> >     
> > >                     <xsl:value-of
> > > select="format-number($numberVal * 100,'0.00')"/>
> > >                     <xsl:text>%</xsl:text>
> > >                   </xsl:when>
> > >                   <xsl:otherwise>
> > >                     <xsl:value-of
> > > select="format-number($numberVal,$ltNumFormat)"/>
> > >                   </xsl:otherwise>
> > >                 </xsl:choose>
> > >               </xsl:if>
> > >               <xsl:if test="$numberVal = ''">
> > >       
> > How can this ever happen since the xsl:when above in
> > the outermost
> > xsl:choose would have been chosen when @val is ''?
> >
> >     
> > >                 <xsl:text
> > > xml:space="preserve">-</xsl:text>
> > >               </xsl:if>
> > >             </div>
> > >           </nobr>
> > >         </td>
> > >       </xsl:otherwise>
> > >     </xsl:choose>
> > >   </xsl:template>
> > >
> > >   <xsl:template match="Cell[not(*)]">
> > >     <xsl:for-each
> > >       
> > select="/Report/Measures/Measure">
> >     
> > >       <td> </td>
> > >     </xsl:for-each>
> > >   </xsl:template>
> > >  
> > > </xsl:stylesheet>
> > >       
> > Regards,
> >
> >
> > Tony Graham.
> >
> >     
> ======================================================================
>   
> > Tony(_dot_)Graham(_at_)MenteithConsulting(_dot_)com  
> > http://www.menteithconsulting.com
> > Menteith Consulting Ltd             Registered in
> > Ireland - No. 428599
> > Registered Office: 13 Kelly's Bay Beach, Skerries,
> > Co. Dublin, Ireland
> >
> >     
> ----------------------------------------------------------------------
>   
> > Menteith Consulting -- Understanding how markup
> > works
> >
> >     
> ======================================================================
>   
> > [1]
> > http://www.w3.org/TR/xpath#section-Boolean-Functions
> >
> >
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