Speed difference under load
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
> > 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?
> you are running something like siege locally on your server then
> 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
> from memcache takes. If using PHP you can get a benchmarking class
> 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
> - John Kramlich
> http://www.gigoit.org - Give and get free items within your community
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