Re: Profiling Tapestry

On Friday, December 20, 2002 11:33 AM, Howard M. Lewis Ship wrote:

> I agree with Marlcom; test under load in a real application.  I'm fairly
> confident that once you add any EJB or database access, the whole Tapestry
> slice of the pie will become pretty thin.

I think you (and Malcom) are downplaying the impact of the web
presentation framework in the overall performance of an application,
which I think is a huge mistake.

I already tested Tapestry "real applications" under load, and I can
assure you that your confidence is misguided, Tapestry applications
absolutely collapse under load.
And not only in laboratory conditions, I see this every day at work.

We have an application (no EJB, simple database access) that people
use to book the lunch at the cafeteria (they browse the menu and make
a choice) and every day between 11:30-12:00 the web server CPU
get pegged at 100% trying to handle requests for about 3500 users,
while the database server just sits pretty with a 1.1 load average.
This didn't happened when the application was written in PHP, and
didn't happen when the application was written in JSP.


> I do think that, with enough work, we could do a lot less unicode-to-ascii
> conversions.  That is, template objects (RenderTemplateHTML instances)
could
> do the conversion just once and emit ascii-binary after that ... but its a
> lot of work.  I'd want to see that this conversion is really causing a
> visible hotspot when the application is running under load.

What proof do you need? ... I already profiled a Tapestry application
and "PrintWriter" appears to be the culprit and I showed you 2
articles that say that use of "PrintWriter" is do be avoided and that
char to byte conversions are slow.

Please don't get me wrong, I love Tapestry, I wouldn't want to use
anything else and I do understand that you have lots of other stuff in
your plate, but Tapestry does have a performance problem, and saying
that "EJB and database access" will eclipse that is just wishful
thinking.

Best regards,
Luis Neves



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