Thanks for your kindly responses to both Sebbaz and Peter.
80 seconds were the average of the 20 concurrent users. The first few threads finished in approximately 30 seconds, some were between 70, 80 seconds, some were more..
I came to the same conclusion, however, the question I'd like to ask is that given that the query can be bad, the performance for 1 user x 20 times average is almost 10 less than 20 concurrent users while using the same query.
When I used SQL PLUS to test the query, the results were displayed after 2 seconds. Similar results were achieved by TOAD. This query was then copied to JDBC sampler, and the results were mentioned as above.
The machine where WAS is running has 2G of RAM, 2 processors, and while running the test memory was increased from 555MB to around 1.5G and then stable. The worst part is the memory usage stayed at 1.5G and didn't drop down, looks like a memory leak somewhere in the app (given that it's J2EE app, but this is another issue). The client that runs JMeter is V880 (unix machine), it's very powerful box. I've also run JMeter on 1G of RAM, Windows XP with JDK1.5. Similar results were achieved.
I am really running out of ideas, please kindly provide further help.
Thanks & regards, Thinh
From: sebb <[EMAIL PROTECTED]> Reply-To: sebb <[EMAIL PROTECTED]> To: JMeter Users List <[email protected]> Subject: Re: Concurrent users Date: Wed, 4 May 2005 11:15:14 +0100
One way to get some idea if JMeter is coping with the load is to replace the HTTP/JDBC samplers with JavaTest samplers (using suitable sleep times).
If JMeter can't cope on your system with these samplers, it's unlikely to be able to cope with the original samplers.
Either way, be sure to have a look at the resource usage on the system (CPU, memory) to see how close you are to the limits.
Also, if your test is quite short, beware of startup/shutdown overheads. These can seriously affect throughput calculations.
To improve JMeter maximum capability: - Use as few Listeners as possible. - use non-GUI mode with no Listeners (one is added automatically).
S.
On 5/4/05, Thinh Nguyen <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> I've started to use JMeter for the last 2 weeks or so. I am trying to do
> some performance testing with 1 user multiple times (eg 20) and 20
> concurrent users at 1 time.
>
> The results that I received for the two scenarios are too much different. An
> average of a user 20 times is around 5 seconds, whereas, average for 20
> concurrent users at 1 time is around 80 seconds.
>
> I understand that concurrent users will be slower, but I don't expect it to
> be that much slower. I am not sure if this problem is part of the tool or
> it's with the code.
>
> I even tried to run the JDBC testing, and the average result are still a lot
> different from 1 user * 20 times compared to 20 users at 1 time.
>
> Could anyone please kindly explain to me or direct me to somewhere that I
> can read/reduce the performance for concurrent users? I am facing the hurdle
> at the moment, please kindly help.
>
> Thanks & Regards,
> Thinh
>
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