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From E S <electric.or.sh...@gmail.com>
Subject Re: Constant throughput timer not giving expected results
Date Tue, 13 Sep 2011 03:40:40 GMT
Well I did some more testing and I have to say that I'm still confused. All
I can figure is that I am misunderstanding how the constant throughput timer
works.

I was able to configure the throughput timer to get the same results as I
did without it (6000 req/sec) but I had to set the total throughput value on
the timer to be really high (about 2,000,000 req/min). I would think the
number should be around 360,000 but for some reason that's not enough. This
is using the "all active threads in the current thread group" mode.

I tried using the "this thread only" mode. I set the test up with 200
threads and the throughput timer to have each thread run at 1800 req/min.
According to my understanding, that is 200 threads each pumping out 30
requests per second for a total of 6000 requests per second. Under this
configuration my total throughput was only 1400 requests per second. I had
to jack up the timer's setting to 22,000 req/min to get the proper
throughput.

I don't get this. Clearly the server is capable of providing the throughput
that I'm looking for. Why do I have to set the timers in such weird ways to
get the throughput to the desired level?

On Fri, Sep 9, 2011 at 6:57 AM, sebb <sebbaz@gmail.com> wrote:

> On 9 September 2011 04:31, E S <electric.or.sharp@gmail.com> wrote:
> > I'm having some trouble getting the Constant Throughput Timer to work the
> > way I want in certain cases.
> >
> > I have a single thread group of 100 threads, all of which are requesting
> the
> > same resource over and over for 1 minute.
> >
> > I attached a Constant Throughput Timer on the thread group and ran a
> series
> > tests with the throughput throttled at higher and higher levels such as
> > 6000, 8000, 10000, etc. Here is a table showing the throughput timer
> > settings and the actual number of requests that the server under test
> > responded to:
> >
> > thruput-setting..........actual-requests-served
> > 36,000.....................36,000
> > 48,000.....................48,000
> > 60,000.....................60,000
> > 72,000.....................60,000
> > 84,000.....................60,000
> >
> > So it looks like the server under test simply can't respond to more than
> > 60,000 requests per minute right? However, when I disable the throughput
> > timer I get way higher throughput, something like 350,000 requests per
> > minute. What's going on here? Why is the throughput timer giving me these
> > results? Is it possible that JMeter is spending so much time trying to
> keep
> > the throughput at the right level that it doesn't have enough cycles left
> to
> > dedicate to actual requests? I tried distributing the load across
> multiple
> > load generators but it didn't seem to help.
> >
> > The results above have the throughput timer configured using Calculate
> > Throughput based on = "all active threads in current thread group". I
> tried
> > changing this to "all active threads in current thread group (shared)"
> and I
> > get the maximum results of 350,000 as if the throughput timer was not
> even
> > there. I must admit I don't understand the difference between the two
> > settings, but neither result sounds right.
> >
> > Any ideas about this?
>
> Create a test plan using the Java Sampler with timer settings that
> correspond to your server.
>
> Run a test with CTT disabled and check you get the desired throughput
> (use Summary Listener).
>
> You can then experiment with the CTT without needing to take server
> and network behaviour into account.
>
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>

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