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From Iago Toral Quiroga <ito...@igalia.com>
Subject Re: Peak tests
Date Fri, 09 Dec 2005 15:51:09 GMT
First of all, thanks a lot for your answer peter,
I comment it between lines:

El vie, 09-12-2005 a las 16:00, Peter Lin escribió:
> for what it's worth, it's nearly impossible to get all 100 requests within
> 500ms. The reason for this is making the initial connection to your
> webserver will have a high initial cost.  How many iterations are you using.

Just one per threadgroup because I want just 100 requests as close as
posible in time. Anyway, I understand what you say about the dificulty
of having all 100 request in 500ms. One thing I think has a lot to do
with this, besides the connection issue you talk about, is the fact that
some threads begin processing their responses before all the threads
send their requests, because this impedes other threads to enter into
CPU and send their requests, but I guess this is not a Jmeter issue, but
a kernel or a JVM matter.

> if you look at all formal performance test specifications, they all have a
> ramp up time. The actual measurement is taken for a period after the server
> has reached a steady state. does that make sense?

> what you need to do is set the iterations to something like 1000. start the
> test and then start counting from like 10minutes after the test started to
> get an accurate measurement.
> 

I get it, but this is not the scenario I want to measure. Besides the
scenario you talk about, we also need to know the maximum number of
requests the web server can handle if they come "at the same time". So,
imagine the web server has no requests to serve, and suddenly, N
requests come about at the same time, what we want to know is: how big N
can be? or what happens when N is like 50, 100, 300,... ?

Notice that I need the server to be "idle" before all the requests come
about, because if it's steady serving responses it's  not servinig just
N requests, but N plus all the requests it was already serving.

Thanks again for hour help.
Iago.

> On 12/9/05, Iago Toral Quiroga <itoral@igalia.com> wrote:
> >
> > El vie, 09-12-2005 a las 15:17, Peter Lin escribió:
> > > I'm not sure I understand why you have 100 thread groups.
> > >
> > > you can put the requests in sequence in 1 threadGroup and increase the
> > > thread count to 100 with 0 second ramp up.
> > > peter
> >
> > Because the requests must be different. If I do what you say,
> > all the 100 threads within the threadgroup will send the same
> > request (the first one in the sequence).
> >
> > I tried using an interleave controller to avoid such problem, but the
> > interleave controller just deals requests for each thread, so the result
> > is the same.
> >
> > Anyway, I've also tried having one thread group and 100 threads within
> > it sending the same HTTP request, but I still have the performance
> > problem I commented in my previous email.
> >
> > Iago.
> >
> >
> > >
> > > On 12/9/05, Iago Toral Quiroga <itoral@igalia.com> wrote:
> > > >
> > > > hi!,
> > > >
> > > > I'm using Jmeter to perform a peak test of my web server (100 http
> > > > requests at the same time). To do such, I've created 100 thread
> > groups,
> > > > each one with one thread that sends a different http request. At the
> > web
> > > > server I log the time (in milliseconds) at which each request is
> > > > received.
> > > >
> > > > I need these requests to be sent to the web server as close as posible
> > > > but I noticed they are are logged at the web server in a period of
> > time
> > > > that varies but is never lesser than 0.8 secs.
> > > >
> > > > ¿Shouldn't jmeter be able to send 100 requests in a leesser period of
> > > > time? ¿Is there any way to boost the launching of these requests?
> > > >
> > > > I've also noticed that, if I enable the option to parse HTML in each
> > > > HTTP request (HTTPSampler.image_parser in jmx file), my web server log
> > > > tells me that jmeter needs 2 or even more seconds to send all the 100
> > > > requests, which leads me to think that some threads start processing
> > its
> > > > response before all requests have been sent ¿can I change this
> > > > behaviour? This is a big problem, because this way, Jmeter is limited
> > in
> > > > its capacity to send the requests as soon as posible to stress the
> > > > server.
> > > >
> > > > My test machine has the following features:
> > > > CPU: 2.4 GHz
> > > > RAM: 512 MB
> > > > OS:  Debian Linux. Kernel 2.6.12.
> > > >
> > > > Thanks in advance for your help.
> > > > --
> > > > Abel Iago Toral Quiroga
> > > > Igalia http://www.igalia.com
> > > >
> > > > ---------------------------------------------------------------------
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> > > >
> > > >
> >
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> >
> >
-- 
Abel Iago Toral Quiroga	
Igalia http://www.igalia.com

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