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From Deepak Shetty <shet...@gmail.com>
Subject Re: what do my test results show?
Date Sun, 30 Jan 2011 23:23:17 GMT
>at what point the website is starting to slow down and reaches breaking
point
This question is probably the subject of a reasonably large book so you
might be better of looking it up there.
The first thing you need to do is define what you mean by slow down and
reaching breaking point
a. Any errors like timeout or a % are considered as site being broken?
b. Acceptable response times (usually also dependent on functionality -
search should be under 2 seconds, login can take upto 3 , checkout can take
upto 4). This is also sometimes defined as a percentile 90% of the requests
for search should be under 2 seconds. You must also factor in varying
network speeds, new users v/s returning users(cached static resources or
cached application data). Also whether you will test each function in
isolation or whether you will say 50% doing search flows, 20% buying
products etc etc.
c. Acceptable server activity (cpu % should not hit above 90% for more than
n seconds or memory etc).
There are many variations and it is upto you to define what these are for
your application.


 >for example, if i set the 'loop count' in the thread group to 'forever',
>does jmeter provide some type of test results which shows how many threads
>have been running
So there is a difference between An Active session and a concurrent
request.  if a thread makes a request , it usually establishes a session on
your server. If you have a test plan with timers then the thread might wait
before making its next request. for a thread group with 100 threads you
might have 100 active sessions but the number of concurrent requests
(usually this is what matters at the server , unless you have large session
footprints) may be smaller. Measuring concurrent sessions is usually easier
at the server level. I believe there is a property in jmeter.properties
where you can configure whether you want this "active threads" figure
outputted onto the result log. If you are using multiple threadgroups or a
plugin like the SteppingThreadGroup , you might want to see a graph that
plots this. You might need to run a test multiple times with varying loads
or varying steps to observe.

Once you have defined what constitutes a slow down, then you can observe
that value in the JMeter listener (or parse the logs to derive that value)
and determine what load your server *breaks* at. Some of these could be out
of the box (e.g. the % of errors or average response time) , and some would
need you to write some code or use a custom plugin (e.g. 85percentile of
request have under this response time). You get some custom plugins here -
http://code.google.com/p/jmeter-plugins/

Again if you are unfamiliar with these kind of activities a book followed by
google is probably your best bet. Most of our views will be biased towards
tests we have run or the way we do it for our applications. Your mileage
will vary.

regards
deepak

On Sun, Jan 30, 2011 at 11:26 AM, kat <skat@btconnect.com> wrote:

>
> hi,
>
> im new to jmeter. i have put together a test plan that runs against a
> website.
> what i am looking for is to see how many users my website can handle and at
> what point the website is starting to slow down and reaches breaking point.
> i have added listeners such as 'view results in table', but i dont really
> understand what its showing me.
>
> for example, if i set the 'loop count' in the thread group to 'forever',
> does jmeter provide some type of test results which shows how many threads
> have been running and whether at what point the site is slowing down?
>
> any help / advice on this matter would be much appreciated.
>
> many thanks
> --
> View this message in context:
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> Sent from the JMeter - User mailing list archive at Nabble.com.
>
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