RE: [xsl] Performance with multiple users during transformation

[Bhupendra Singh <skbhupendra@xxxxxxxxxxx>]

Michael ,
Thanks for the input, Heres what you requested for.

> You need to explain your measurement scenario more
> carefully. How is the
> XSLT processor running - as a servlet? 

The XSLT processor is running as a servlet. Its a Web
based application, which takes client request with
Servlets. The serlvet brings the data in XML format
and then uses the transformer to make another XML,
which is send back to the user.

>How are you
> measuring response time?

I am taking the diference of the time before and after
the Transformer.transform() method and printing it in
a log file.

> Are
> these transformations all
> using the same stylesheet? 

All the users are requesting the same page with the
same parameter, so the same input XML and stylesheet
is used.

>Are you saving the
> compiled stylesheet in memory?

I am storing the compiled XSLT as templates in a
Hashmap. I use this Template to create a new
Transformer object using the
templates.newTransformer().
Before taking the test I am running a dummy user
request to build this template in the Hashmap.

> Are they all running in the same thread, or do you
> have a pool of
> threads/processes?
Each user fires the request from different IE
sessions. Thus the servlet threads will be different
for each.


>how much memory you
> are allocating to the Java VM, 
I have kept the minimum JVM heap size to 1 GB for
Websphere App server.


 --- Michael Kay <mike@xxxxxxxxxxxx> wrote: 
> > I have a 250 KB XML to be transformed into another
> XMl
> > document. I am using a high end UNIX box with 8
> CPUs
> > and 32 Gig RAM. 
> > Intially I was using Xalan and the timings for
> > transformation are as follows:
> > 1 user : 3 secs
> > 2 users: 6 secs
> > 4 users: 8 secs
> > 
> > Then I changed to Saxon8 and the timings are
> > 1 user : 1.5 secs
> > 2 users: 3 secs
> > 4 users: 4 secs
> > (I fear whats going to happen when 1000 users will
> use
> > the applicaiton)
> 
> You need to explain your measurement scenario more
> carefully. How is the
> XSLT processor running - as a servlet? How are you
> measuring response time?
> What is the think time between transactions? Are
> these transformations all
> using the same stylesheet? Are you saving the
> compiled stylesheet in memory?
> Are they all running in the same thread, or do you
> have a pool of
> threads/processes?
> > 
> > Although I got a 50% performance enhancement with
> > Saxon for each scenario, but I still dont
> understand
> > one thing why do we have the increase in
> > transformation timing as the users increase.
> 
> That depends very much on how the work is being
> scheduled, which is why I
> asked about your execution environment. 
> 
> > Since Saxon is based on SAX parsing there should
> be no
> > memory constrained (Also my 32 Gig RAM is never
> > utilised more than 5GB at any time.)
> 
> No, that's a bad misunderstanding. Every XSLT
> processor today builds the
> source document in memory. However, 250Kb is not
> particularly big. Again,
> however, it depends on how you are scheduling the
> work, how much memory you
> are allocating to the Java VM, and so on. 
> > 
> > Can somebody briefly tell me how the
> transformation
> > works, starting from how the XSL is parserd, how
> the
> > XML is parsed and then the transformation.
> > Can the parser and the XSLT processors be
> different.
> 
> If you're using Saxon, then the article at
> http://www.xml.com/pub/r/1065 may
> be helpful.
> 
> Michael Kay
> http://www.saxonica.com/
> 
>  

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