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Posted to user@jmeter.apache.org by David Heath <da...@davidheath.org> on 2008/09/26 10:39:00 UTC

Recommended parameters for modelling user request behaviour

Hi,

Hello I'm new to JMeter and this mailing list so firstly, thanks for a
great tool! I'm a web software developer and I'd like to use JMeter to
load test a web application I'm developing.

I have set up a test which is intended to model a representative
sample of user behaviour. The test performs a user login and various
common actions. I want to use this to answer the question "what is the
mean response time at a given level of concurrent users?". To this end
I ran the test repeatedly with thread numbers from 2, 4, 8, 16, 32,
64, and then looked at the results.

The answer I got was that at loads of 16 or more threads I was getting
response times of 6 seconds or more. This is clearly not acceptable
for any application. So, before I start digging into my code to try to
find out what's going on, I wanted to sanity check that my model is
reasonable. One area that I'm not sure about is the introduction of a
random delay between user requests. I did this by adding a Guassian
Random Timer as a child of the root Thread Group. If understood
correctly, this random delay will get applied to all HTTP samplers in
the tree. I used a mean of 700ms and standard deviation of 400ms.

So, I have two questions:
  1) have I understood correctly that the timer gets applied to the
whole tree .. I don't need to add one for each HTTP sampler?
  2) do the figures of mean 700ms and stdev 400ms seem reasonable? I
wonder if it's a bit too short?

Thanks in advance for any advice you can give.

David Heath
http://davidheath.org/

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Re: Recommended parameters for modelling user request behaviour

Posted by David Heath <da...@davidheath.org>.
Hi Sebb,

Thanks for your reply.

>>   2) do the figures of mean 700ms and stdev 400ms seem reasonable? I
>>  wonder if it's a bit too short?
>
> What are the users likely to do?
> That depends on how much info is in your pages.

Lets say it's something of a similar complexity to amazon, so a user
may be searching for something to act on, or they may be browsing
things to find something to act on. I don't really have hard data for
user behaviour because the application is still under development and
we have only had a small number of invited users to test it. So, I'm
trying to predict the future a bit here which is why I'm interested to
know how others have modeled this.

How should I go about choosing suitable values? Is the guassian random
timer the best thing to use? What parameters do you use?

Thanks

David

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Re: Recommended parameters for modelling user request behaviour

Posted by sebb <se...@gmail.com>.
On 26/09/2008, David Heath <da...@davidheath.org> wrote:
> Hi,
>
>  Hello I'm new to JMeter and this mailing list so firstly, thanks for a
>  great tool! I'm a web software developer and I'd like to use JMeter to
>  load test a web application I'm developing.
>
>  I have set up a test which is intended to model a representative
>  sample of user behaviour. The test performs a user login and various
>  common actions. I want to use this to answer the question "what is the
>  mean response time at a given level of concurrent users?". To this end
>  I ran the test repeatedly with thread numbers from 2, 4, 8, 16, 32,
>  64, and then looked at the results.
>
>  The answer I got was that at loads of 16 or more threads I was getting
>  response times of 6 seconds or more. This is clearly not acceptable
>  for any application. So, before I start digging into my code to try to
>  find out what's going on, I wanted to sanity check that my model is
>  reasonable. One area that I'm not sure about is the introduction of a
>  random delay between user requests. I did this by adding a Guassian
>  Random Timer as a child of the root Thread Group. If understood
>  correctly, this random delay will get applied to all HTTP samplers in
>  the tree. I used a mean of 700ms and standard deviation of 400ms.
>
>  So, I have two questions:
>   1) have I understood correctly that the timer gets applied to the
>  whole tree .. I don't need to add one for each HTTP sampler?

Yes. No.

>   2) do the figures of mean 700ms and stdev 400ms seem reasonable? I
>  wonder if it's a bit too short?

What are the users likely to do?
That depends on how much info is in your pages.

>  Thanks in advance for any advice you can give.
>
>  David Heath
>  http://davidheath.org/
>
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>  To unsubscribe, e-mail: jmeter-user-unsubscribe@jakarta.apache.org
>  For additional commands, e-mail: jmeter-user-help@jakarta.apache.org
>
>

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