JMeter Threads, Ramp-up and Loop what the correct usage?

Question

I am under the impression that I use the 3 settings; Threads, Ramp-up and Loop, to simulate X (Threads) amount of users/thread over Y (Ramp-up) seconds and do these for Z (Loop) amount of times. For example I want 10 users every 1 second for 1 hour which equates to 10 Threads, 1 Second Ramp-up and 3600 Loops.

But :)

Others seems to be using it differently ... as in if they want the same as above they would set Threads to 36000, Ramp-up to 3600 seconds and Loop to 1.

I tend to think the first approach is correct based on #a it reads better :) and #b why would you have a setting based in seconds to indicate the length of your test

Can anyone give me a definitive answer or are both options plausible?

So there should only be 10 users performing the action at any one time? Or does the amount of users performing the action increase over the course of test (10 in second#1, 20 in second#2...) — matt freake
The documentation states that if you want 5 threads and a ramp-up time of 5 seconds then it will spread the creation and execution of the threads over the Ramp-up time of 5 seconds, so in that case 1 per second. — Billy

matt freake matt freake · Accepted Answer · 2014-09-03T12:46:06

Firstly 36000 threads in the second example seems very high! http://wiki.apache.org/jmeter/HowManyThreads reports people using 1000. So the 2nd scenario may not even work.

The two scenarios you describe are not exactly the same, and I'm not sure if either are exactly what you want.

In the first the 10 Threads plus 1 second Ramp-up means all 10 Threads will be in use after 1 second. The 10 Threads will then do their actions in parallel 3600 times. You have not mentioned anything that will mean the test will take 1 hour, it will take as long as it takes to loop through 3600 times. To make it take an hour (assuming the actions don't take longer than 1 second) you would need something like a Constant Throughput Timer within your loop which control the speed of the loop so that it takes an hour.

In the second, 10 threads would be created in second #1 and start doing their loop, another 10 in the second#2, etc, all the way up to 1 hour (second#3600). If the actions take longer than one second, then you would have more than 10 threads running in any one second.

The first approach is much clearer. The 2nd one is a misuse of the Ramp-Up; it's not being used to provide a ramp-up to 360000 threads, but to try and schedule 10 threads to run at once.

JMeter Threads, Ramp-up and Loop what the correct usage?

1 Answers