On 12/11/2007, Dan Keeley <[EMAIL PROTECTED]> wrote: > Hi, > > We are seeing some regular (20second apart) spikes in our throughput.
Do you mean that the throughput suddenly increases? Are the requests still successful? > We suspect these are from the application tier, but are not 100% sure. So i > just wanted to check whether jmeter will put through a constant rate of > requests after the ramp-up period and whether or not it could be responsible > for these peaks? The rate at which JMeter generates requests depends on what timers are present in the plan. Some combinations of random timers and controllers could cause spiky behaviour. > They are always 20 seconds regardless of high or medium throughput so i > pretty much discount garbage collection. Although i'm learning it's > dangerous to ignore things such as this! I agree, it seems a bit unlikely that it is GC. Have you checked the elapsed times? Do they show a pattern? Also check the gaps between request initiation. Are they consistent with the test plan? Fluctuations in elapsed times are more likely to be caused by resources external to the JMeter host. Fluctuations in request initiation could be caused by JMeter probems (or possibly JMeter host problems) - but remember that the Constant Throughput timer will adjust the gaps to try and maintain a suitable rate. You could try running the test plan against the JMeter mirror server and see how that behaves. Reduce JMeter resource usage by following the advice here: http://jakarta.apache.org/jmeter/usermanual/best-practices.html#lean_mean You can also try dividing the load between multiple independent JMeter instances so that each one is only processing a low throughput. Check that they all run OK independently, and then start them together. If you then start seeing the problem, then it must be some resource that is common to all the instances, e.g. the application or perhaps the network. Check what the OS monitoring tools show on the different hosts. > Thanks, > Dan > > > --------------------------------------------------------------------- > 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]
