Jmeter HTTP Request: how it really works

0
votes

I have executed couple of Jmeter tests so far. My test plan in very basic one. I'm using Jmeter 5.2 on mac environment.

Number of threads: 500
Ramp-up period: 1
Loop count 3
[x] Same user on each iteration
[ ] Delay thread creation until needed
[ ] Specify thread life time

Basically according to my configuration above, the test will have 500 different threads being spawned in my JVM while this load test is running.

In order to create 500 threads, Jmeter has time restriction of just 1 second only. So, it will create the one thread in each 0.002 seconds from the moment I start the test.

I'm just hitting to an deployed publicly available service with HTTP POST request with a valid payload.

Now my real question

It is possible that the very first request that Jmeter sends will get the response from the server in just 0.2 seconds(200ms). What happens to that thread from that moment? Will this thread being killed after that?

2
jmeterperformance-testingjmeter-5.0
you want to assert the response time of only first request? – user7294900
No, I don't want to assert anything. I want to know what happens to the first few threads that has already got the responses from the server. Will they be killed by the jmeter or keep retrying over and over again? – Jude Niroshan
You define loop e, so each thread it will loop 3 times, rampup is just start time if thread, not the end time (set Duration for end time) – user7294900
ohh yeah, it makes sense. I thought loop count is for the whole test bundle(500 threads consider as one loop iteration) So, 3 times will end in 0.6 seconds. (0.2sec * 3). What happens after this? – Jude Niroshan

2 Answers

2
votes

Ramp up period doesn't stop thread, setting Duration will stop(/kill) thread if reach duration time,

Each thread execute independently until it finishes his last loop,

So in your case each thread will end after ~0.6 seconds (0.2 second per request * 3 loops)

1
votes

  1. It is possible that the very first request that Jmeter sends will get the response from the server in just 0.2 seconds(200ms) - yes, it may be even less, the question is whether your application can respond in 200 ms or less

    enter image description here

  2. What happens to that thread from that moment? Will this thread being killed after that? - for particular your set up if there are no more Samplers to execute the thread will execute this HTTP Request sampler 2 more times and after that it will be asked to stop.

You can increase JMeter logging verbosity to whatever level of details you want and inspect jmeter.log file in order to get the idea regarding what's going on under the hood of JMeter. Basic details can be obtained without any configuration tweaks:

enter image description here