lot of hits in one go - server overloading questions

Hi Folk

I am making a website that is going to get lots of hits in one go (they will
be doing lots of advertising). I am a bit scared the whole thing will fall
over because it will get too many hits at one time. My questions are:

a. has anyone got any experience with this?
b. what is a lot?
c. are there any techniques to reduce the load on the server (e.g. changing
PHP files into HTML ones)?
d. is there a way to measure server load and calculate expected load with X
number of visitors?
e. etc...

TIA

- Nicolaas

re: lot of hits in one go - server overloading questions

windandwaves wrote:[color=blue]
> b. what is a lot?[/color]

No easy answer. Depends a lot on the hardware and bandwidth, as well as
the nature of the site. Some years ago I was on a team building the
launch site for a certain next-generation video game console. The
requirements called for 20 million hits on the first day IIRC.
[color=blue]
> c. are there any techniques to reduce the load on the server (e.g. changing
> PHP files into HTML ones)?[/color]

Zend sells a number products that are supposed to improve performance.
Code execution speed usually isn't a big factor though. Scalability is
usually limited by the database. So I would avoid hitting the database
as much as possible. For example, if you have a drop-down list of US
states, don't populate it with data from the database. It's quite
unnecessary as the list isn't going to change anytime soon.
[color=blue]
> d. is there a way to measure server load and calculate expected load with X
> number of visitors?[/color]

For quotable numbers, you really need a commercial tool. LoadRunner
from Mercury Interactive and SilkTest from Segue come to mind.

For a very rough estimate, in the past I've done something as simple as
sticking <script> location.reload() </script> into my page footer and
opening up a bunch of browser windows.

re: lot of hits in one go - server overloading questions

Chung Leong wrote:[color=blue]
> windandwaves wrote:[color=green]
>> b. what is a lot?[/color]
>
> No easy answer. Depends a lot on the hardware and bandwidth, as well
> as the nature of the site. Some years ago I was on a team building the
> launch site for a certain next-generation video game console. The
> requirements called for 20 million hits on the first day IIRC.
>[color=green]
>> c. are there any techniques to reduce the load on the server (e.g.
>> changing PHP files into HTML ones)?[/color]
>
> Zend sells a number products that are supposed to improve performance.
> Code execution speed usually isn't a big factor though. Scalability is
> usually limited by the database. So I would avoid hitting the database
> as much as possible. For example, if you have a drop-down list of US
> states, don't populate it with data from the database. It's quite
> unnecessary as the list isn't going to change anytime soon.
>[color=green]
>> d. is there a way to measure server load and calculate expected load
>> with X number of visitors?[/color]
>
> For quotable numbers, you really need a commercial tool. LoadRunner
> from Mercury Interactive and SilkTest from Segue come to mind.
>
> For a very rough estimate, in the past I've done something as simple
> as sticking <script> location.reload() </script> into my page footer
> and opening up a bunch of browser windows.[/color]

might try that... brilliant.

one more question: if I add include_once("library/functions5.php") to a
bunch of scripts (with a myriad of functions), does that add a lot of
weight? I am adding these by default, because then I do not have to think
which page needs then and which page does not.

Thank you for the detailed answer.

- Nicolaas

re: lot of hits in one go - server overloading questions

windandwaves wrote:[color=blue]
> might try that... brilliant.
>
> one more question: if I add include_once("library/functions5.php") to a
> bunch of scripts (with a myriad of functions), does that add a lot of
> weight? I am adding these by default, because then I do not have to think
> which page needs then and which page does not.[/color]

It's unlikely to have a noticeable effect. The server can read and
parse the file far faster than it can transmit output data through the
network. Any overhead is through masked by the low throughput.

Scalability issues are usually caused by resource contentions as oppose
to cumulation of independent loads. Usually that resource is the
database. For example, while one request is writing to a table,
requests reading from the same table might need to wait for that
operation to finish before proceeding. Another common contention
problem in PHP involve session locking. Simultaneous requests from the
same user (e.g. from a frameset) could end up blocking each other if
each tries to open the user's session. Not really a scalability issue
but could be mistaken as one.

re: lot of hits in one go - server overloading questions

On Wed, 28 Sep 2005 09:37:12 +1200, "windandwaves" <winandwaves@coldmail.com>
wrote:
[color=blue]
>d. is there a way to measure server load and calculate expected load with X
>number of visitors?[/color]

Apache comes with a simple benchmarking tool named "ab" which you can use to
throw lots of (concurrent) requests at a single URL and get some timing
information back. It's not a very realistic test, but gives you an initial
indication of how the site may perform.
--
Andy Hassall :: andy@andyh.co.uk :: http://www.andyh.co.uk
http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool