> -----Original Message----- > From: sebb [mailto:seb...@gmail.com] > Sent: Wednesday, September 14, 2011 3:12 PM > To: JMeter Users List > Subject: Re: Startup Cost on first operation > > On 14 September 2011 19:20, Nicholson, Brad (Toronto, ON, CA) > <bnichol...@hp.com> wrote: > >> -----Original Message----- > >> From: sebb [mailto:seb...@gmail.com] > >> Sent: Wednesday, September 14, 2011 1:29 PM > >> To: JMeter Users List > >> Subject: Re: Startup Cost on first operation > >> > >> 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? > > > > Yes - I've run it against a number of different hosts and the first > request is always significantly higher. > > > > > >> Which sampler are you using? > > > > HTTP Request > > Yes, but which implementation? > Java, HttpClient3.1, HttpClient4?
How can I tell? I built the test with the Jmeter 2.4 GUI and added them with Add->Sampler->HTTP Request > >> Are you using Keep-Alive? > > > > Yes > > > >> If you switch it off, each sampler will have to create the > connection > >> anew, so I would expect all the samples to take longer. > > > > I tried with keep alive off and there is no statistically interesting > difference. First operation is always around 600ms, all subsequent run > between 8ms to 25ms. It's the same for both keep-alive enabled and > disabled. I've tested with a variety of URL's btw, and the result is > always the same. > > Are some of these URLs public? > > If so, can you create a Bugzilla issue and attach the JMX test script? None of the URLS are public. I will see if I can get a test case together that does the same using a public URL though. Thanks, Brad. --------------------------------------------------------------------- To unsubscribe, e-mail: jmeter-user-unsubscr...@jakarta.apache.org For additional commands, e-mail: jmeter-user-h...@jakarta.apache.org
