On 07/08/2008, Rinke Heida <[EMAIL PROTECTED]> wrote: > We are testing a web application with JMeter 2.3.1 and are getting slow > responses while increasing the number of threads. > The test is distributed over 4 VMWare client PC's/Windows XP Pro, all > running JMeter. > Every VM: Intel Xeon CPU, 3 GHz, 1 GB RAM > > The clients use one of three similar web servers. > > Doing 200 threads (ramp-up 120 sec) per client goes OK, a simple request > for a GIF does below 100 ms and sometimes even below 10 ms. > Running 330 threads (ramp-up 120 sec) per client suddenly has responses of > the same GIF of between 500 and 1000 ms. > Note: the response times of a GIF is not the goal of this testing, but made > us think the client got problems. > > Splitting these 330 threads over two clients (we now have 8 clients > running) gives the same fast responses for this GIF below 100 ms or below 10 > ms. > So the webservers get the same load, but the performance is different. > > At first we thought the webserver was hitting a performance problem, but > scheduling the same amount of threads over double the clients gives a good > performance again. > In the JMeter logs I can't find any problems. Memory does not seem the > problem. > > Is there an explanation for this? > Can the client influence the perfomance and thus the response-times?
In theory, yes. But I would expect the throughput to be influenced more than the response time. The code that performs the sample is generally quite short, and should not have any reason to be affected much by other threads, unless there is severe resource starvation (e.g. lack of CPU). JMeter does a lot more work between samples, and some of that may require waiting for a shared resource to become available - any such waits will affect the throughput. But of course if the JVM is not quick to resume a thread when IO completes, this will affect response times. > Regards, > > -- > Rinke Heida > > ARIS b.v. > Burgemeester Falkenaweg 104, 8442 LH Heerenveen, The Netherlands > Tel +31-(0)513-629981, E-mail [EMAIL PROTECTED], Http://www.aris.nl > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
