Hi Steve
>In Professional JSP, it briefly mentions that the use of custom tags may
>impact application performance by adding an additional layer to the
>processing. Does anyone have any insights that can be shared about
>extensive use of custom tags and performance impacts? Are the performance
>impacts only experienced on the initial compilation of the pages, or are
>there other issues?
>
As the writer of this quote from the book I should take the time to expand
what is said here.
For small or average applications Tags should really have no major impact on
the practical performance of your application. In other words the user will
see the page in acceptable response times, since the .1 second delay (for
arguments sake) it might add to the page processing time is small for the
overall page being sent to the user. For what I have done, Tags haven't been
an issue for my applications. However, I haven't tested Tags on Larger
Applications which would require every bit of processing power, since I
build smaller web applications
where load is never an issue. So I can't give you hard and fast numbers
when the breakeven point will be.
The real point of the quote is to remind the reader that cost of the tag
comes in the form of it having add another design layer. For simple tags
this extra layer shouldn't pose any particular problems. However, if you
exercise bad design practices this extra layer could be a problem. Also
depending on how the JSP Container executes Tags there can be different
performance characteristics. So If your application is experiencing problems
in performance, or if you are planning to scale your site to large traffic
requirements, means you should
carefully examine your design and benchmark your design so you will know
what to expect. This is important in any web application in general. It
might mean on some tags you move code to a different format which doesn't
use tag.
The fact of the matter is I could probably expand the one quote you read
into a several chapter explanation and overview of Tag performance and
optimization , as there are many issues and factors involved in the
performance. But again this is true in for most of the things we do in
web application design. So the real point of the quote is to help make us be
aware that everything we do has a price. In tags, we gain a easy interface
at the cost of another layer. There is extra work involved with the
processing of the layer. Tags might be simple to use, but
we need to be prepared to pay for the cost of the simplicity. But there are
no hard and fast rules on the actually timing effect as there are so many
variables involved with the final speed of the actual Usage of the Tag. Also
rules we learn now, could be wrong for future releases of
JSP or JSP Containers. This means optimize when you have a problem and pay
attention when you know you will have load issues, but again this reflects
paying attention to general Java Design practices.
One bench mark I came across in the struts archive you might find handy:
While it wont tell you much as far as the impact of the tag design, it does
give you an idea of how the container effects tag performance.
> > > From: Jeff Schnitzer [mailto:[EMAIL PROTECTED]] > > Sent: Monday,
>March 19, 2001 11:24 PM
> > > To: [EMAIL PROTECTED] > > Subject: RE: Performance of
>struts
> > >
> > >
> > > Struts should suffer the same performance issues as WebWork. There
>are
> > > a handful of benchmarks here:
> > >
> > >
>http://sourceforge.net/docman/display_doc.php?docid=2243&group_id=14797#Na96
> > >
> > > The relative performance on a tag-heavy benchmark:
> > >
> > > Tomcat 3.2: ~380 milliseconds
> > > JRun 3.0: ~350 milliseconds
> > > Resin 1.2.1: ~250 milliseconds
> > > Orion 1.3.8: ~220 milliseconds
> > > WebLogic Server 6.0: ~140 milliseconds
> > >
Hope this helps to start to answer your question. It will be interesting to
hear other peoples stories and benchmarks in using Tags.
Casey Kochmer
[EMAIL PROTECTED]
www.jspinsider.com
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