Speed difference under load

Dustin Sallings dustin at spy.net
Sat Oct 27 03:52:29 UTC 2007

   Depending on the language and runtime, you could almost count on it  
while libraries load and initialize and jits optimize.

   Testers usually include some ramp-up time where things sort of warm- 
up before you actually start capturing metrics.

Dustin Sallings (mobile)

On Oct 26, 2007, at 20:24, "K J" <sanbat at gmail.com> wrote:

> Ok I tested this, and found that the very first memcache get request  
> always takes up 1 second.  All subsequent gets in the same page are  
> fast.  Does anyone know what could cause the first memcache get  
> request to slow down like this?
> On 10/25/07, John Kramlich <john.kramlich at gigoit.org> wrote:
> J A wrote:
> > In my application I've noticed something weird.  When testing it  
> with
> > one user, the memcached page loads in like 1 second, but when I  
> use a
> > load testing software and put 20 simultaneous users on it, the page
> > load goes to 0.01 second, even though the server load has gone up.
> >
> > I'm puzzled by this.  Anyone have similar experiences?
> >
> What load testing software are you using and what happens if you
> configure that load testing software to emulate only a single user?   
> If
> you are running something like siege locally on your server then  
> network
> latency would be much lower than if you were running the same  
> program on
> a remote machine.  That may be what makes the page load more slowly.
> You may also want to profile you code and see how long returning  
> results
> from memcache takes.  If using PHP you can get a benchmarking class  
> from
> PEAR and set start and stop markers before and after you memcache
> related code.  Then you can output the number of milliseconds it takes
> to execute that code.  You can do this for other parts of your code as
> well.  It certainly helps when figuring out where to spend time  
> optimizing.
> - John Kramlich
> ------------------------------
> http://www.gigoit.org  - Give and get free items within your community
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