[ILUG] Slightly OT: Suggestions for performance testing PHP website

[Rafiq Maniar]

Hey,
I've done a lot of testing with siege, AB, and httperf - and they're great
for
testing webserver load, but not necessarily application load.

They make a connection to a page (or in the case of siege or httperf, a set
of pages user-definable), download
or simulate download of the content, and disconnect. They don't really
simulate an active user - one who clicks on various links, submits data,
i.e. someone
actually using the application as opposed to simply loading a page.

The problem with hitting the same page or group of pages over and over is
that
your performance tests with AB et al will be better than real-life.

Say you hit the index.php 5000 times with AB - after the very first time,
that file
has been read by the OS and is now cached in local buffers (actually this
applies to Linux, I would
assume the same on Windows, but who knows). Also, whatever requests that
PHP made to your DB are now cached by PGSql. So for the other 4999 requests,
they're being accessed to a lesser or greater extent from memory rather than
disk.

Thats all well and good if this is all a user will ever be doing (i.e.
loading index.php), and reflects
a normal usage scenario - however if there's more user interaction going on,
which I assume
there is, then its not quite as useful as a test.

Thats not to say its not worth doing with these tools, just be aware of what
you
are and are not testing.

Rafiq

On Tue, Dec 2, 2008 at 4:27 PM, Phil Bradley <philb at vodafone.ie> wrote:

> Rob Gallagher wrote:
>
>> Siege [1] is pretty cool. You might also want to check out httperf [2]
>> if you want to benchmark the webserver itself.
>>
>> [1] http://freshmeat.net/projects/siege/
>> [2] http://www.hpl.hp.com/research/linux/httperf/
>>
>
>
>
> Hi Rob, Paul,
>
> Thanks for wading through my lengthy post, so far ApacheBench looks to do
> what I want but I'll check out siege and httperf as well.
>
> Cheers,
>  -Phil
>
>
>
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