Re: [xsl] Performance improvement for a recursive function?

[Wolfgang Laun <wolfgang.laun@xxxxxxxxx>]

A value 400 is in a comment in the xsl.
-W

On 13 December 2011 11:04, Michael Kay <mike@xxxxxxxxxxxx> wrote:
> What is a suitable value for the parameter $scale?
>
> (It would be a good idea to declare the type of the parameter, both for
> documentation and for performance, though I have no idea whether this makes
> a significant contribution - probably not.)
>
> Michael Kay
> Saxonica
>
>
> On 13/12/2011 00:07, Manfred Staudinger wrote:
>>
>> Hi,
>>
>> I need some help to improve the performance of a function, as I have
>> run out of ideas what to change!
>>
>> In the process to convert some data to SVG I transform (or even break
>> up) @Data attribute of the Path element and then use the function
>> my:compose-path-data [1] to put the parts together into a string
>> again. The attribute string is a succession of path commands, where
>> each path command  (see the global variable below) consists of a one
>> byte character followed by zero, one, or two integers. Having about
>> 2200 Path elements, most of them have a @Data attribute with between 5
>> an 50 path commands.
>>
>> A few attribute strings are bigger (up to 1MB) and contain up to
>> 100000 path commands. As the function is called for each path command
>> it is tail recursive, but the performance is still a big problem: to
>> process 41337 path commands it takes 861 sec! The first 5000 path
>> commands are processed in 14 sec (at 355.87 per sec) the last 5000
>> take 671 sec (only at 7.5 per sec).
>>
>> What Saxon reports [2] is consistent with the above. In case you want
>> to try it, I have uploaded the specific test case here:
>>    http:///test.rudolphina.org/test01-perform-data.xsl
>>    http:///test.rudolphina.org/test01-perform-data-org.xml
>>
>> Using Saxon-HE 9.3.0.5J and Java version 1.6.0_14 on Windows. XP Home.
>> Hardware ASUS Eee PC 1000H with Intel. Atom N270 (1.60 GHz)
>>
>> Regards,
>> Manfred
>>
>> [1]
>> <xsl:function name="my:compose-path-data" as="xs:string*">
>>    <xsl:param name="c" as="xs:integer*"/>
>>    <xsl:param name="i-c" as="xs:integer"/>
>>    <xsl:param name="xy" as="xs:integer*"/>
>>    <xsl:param name="i-xy" as="xs:integer"/>
>>    <xsl:param name="i-end" as="xs:integer"/>
>>    <xsl:param name="result" as="xs:string?"/>
>>    <xsl:variable name="cmd" select="key('path', $c[$i-c], $path-cmd)"
>> as="element()?"/>
>>    <xsl:sequence select="if ($i-c gt $i-end)
>>       then $result
>>       else my:compose-path-data($c, $i-c + 1,
>>          $xy, $i-xy + xs:integer($cmd/n),
>>          $i-end,
>>          concat($result, $cmd/@char, if ($cmd/n=2)
>>             then (: M, m, l, (blank) :) concat($xy[$i-xy], ',',
>> $xy[$i-xy+1])
>>             else  if ($cmd/n=1)
>>                then (: h, v :) string($xy[$i-xy])
>>                else (: z :) ())
>>          )"/>
>> </xsl:function>
>>
>> and on the stylesheet level
>> <xsl:variable name="path-cmd">
>>    <path>
>>       <cmd char=" "><n>2</n><code>32</code></cmd>
>>       <cmd char="M"><n>2</n><code>77</code></cmd>
>>       <cmd char="l"><n>2</n><code>108</code></cmd>
>>       <cmd char="m"><n>2</n><code>109</code></cmd>
>>       <cmd char="h"><n>1</n><code>104</code></cmd>
>>       <cmd char="v"><n>1</n><code>118</code></cmd>
>>       <cmd char="z"><n>0</n><code>122</code></cmd>
>>    </path>
>> </xsl:variable>
>> <xsl:key name="path" match="cmd" use="xs:integer(code)"/><!-- $path-cmd
>> -->
>>
>> [2]
>> Stylesheet compilation time: 4218 milliseconds
>> Using parser org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser
>> net.sf.saxon.tree.tiny.TinyBuilder
>> Tree built in 1375 milliseconds
>> Tree size: 4 nodes, 0 characters, 11 attributes
>> Execution time: 14m 31.579s (871579ms)
>> Memory used: 36559128
>> NamePool contents: 33 entries in 33 chains. 8 prefixes, 8 URIs