Re: [xsl] Performance with multiple users during transformation

[Geert Josten <Geert.Josten@xxxxxxxxxxx>]

> > 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?

I was about to ask the same questions.. :)

Bhupendra:
Running your processor as a servlet or in some other persistent form gives the opportunity to cache 
memory objects. Though 250Kb is not really big, it does take time to parse (read into memory).

Actually, usually the number of times a document (XSL or XML) is being read is of bigger impact on 
the performance than the document size. So you want to prevent reading documents multiple times when 
once would be sufficient.

By the way, I wouldn't be surprised if loading (and compiling) the stylesheet will prove to be 
slower than reading the 250K XML document..

> > 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. 

On the other hand, it does make a difference if you catch the result as SAX events and/or serialize 
it directly instead of first creating a DOM tree out of it. :)

Though presumably not that much as saving the compiled stylesheet...

G.