On 14 September 2011 17:57, Nicholson, Brad (Toronto, ON, CA) <bnichol...@hp.com> wrote: >> -----Original Message----- >> From: sebb [mailto:seb...@gmail.com] >> Sent: Wednesday, September 14, 2011 11:27 AM >> To: JMeter Users List >> Subject: Re: Startup Cost on first operation >> >> On 14 September 2011 16:14, Nicholson, Brad (Toronto, ON, CA) >> <bnichol...@hp.com> wrote: >> > Hi, >> > >> > I am using jmeter 2.5 and I am triggering my test via Ant and using >> the Jenkins Performance Plugin to display the data. >> > >> > With each test I run, the first result has heavily inflated times >> (hundreds of milliseconds instead of a few). I'd like to avoid having >> such high numbers in the initial operation. Google seems to imply that >> this is paying the complication time of the jmeter script during this >> operation. >> >> Do you mean compilation time? > > Sorry, yes - I mean compilation time. > > >> If so, that is done before the sample is started; sample times include >> only the time needed to perform the sample. >> >> > I can absorb the cost of this operation by adding a dummy operation >> at the start of the test, but I am wondering if there is a >> simpler/cleaner way of doing this? >> >> That should not be necessary; there must be something else happening >> here. >> >> Try using a Java sampler. Does the first sample take longer than the >> next? > > No - they are fairly uniform > >> What happens if you add a dummy before that? > > Dummy request takes a higher startup time, no change the Java request. > > All my requests (including the dummy request) are HTTP Request's and are > connecting via https.
https is much more expensive in connection setup >> Are you sure that the Jenkins Performance plugin is measuring samples, >> and not JMeter startup time? > > I'm sure it's not. I've confirmed by checking the raw output files written > by Jmeter. To completely eliminate other moving pieces, I've re-run the test > repeatedly directly from Jmeter and I see the same behavior. The only thing I can think of that might be causing the problem is the connection setup. First time JMeter init for a connection will be slightly slower, but should barely be noticeable; it will be the external stuff that takes the most time. And that will apply to browsers as well. Does the additional time apply to other target hosts? Which sampler are you using? Are you using Keep-Alive? If you switch it off, each sampler will have to create the connection anew, so I would expect all the samples to take longer. AFAIK, JMeter itself does not do any expensive first-time init for either https or http (obviously if it does that should be fixed to exclude that time). However connections do have a setup overhead, which will apply to any application, including browsers, and need to be included in the JMeter sample time. > Brad. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: jmeter-user-unsubscr...@jakarta.apache.org > For additional commands, e-mail: jmeter-user-h...@jakarta.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: jmeter-user-unsubscr...@jakarta.apache.org For additional commands, e-mail: jmeter-user-h...@jakarta.apache.org
