Incorrect graph generate by jmeter listener Hits per Seconds and Composite Graph

2
votes

learning using jmeter and getting problem when reading graph listener output

  1. creating Thread group with number thread 8, ram-up 1 and loop forever enter image description here

  2. adding listener active threads over time, hits per seconds, response times over times

result: a. in Active Threads Over Time getting correct result with maximum 8 thread enter image description here

b. in Hits per Second, graph result is really weird, there is 148 number of hist/sec enter image description here

trying to debug and change thread to 1, Hits per Second still generate weird graph with 20 hits/sec enter image description here

any idea why this happening? i use latest release from jmeter 3.0

1
jmeter

1 Answers

4
votes

As I had clarified here, jp@gc - Hits per Second, this listener shows the total number of requests sent to the server per second. Per Second is by default - it can be changed in the settings tab.

When you have 1 user, JMeter sends 18-20 requests / second (Loop forever will keep sending the requests for the user as soon as the user gets the response). So, The user was able to make 19 requests in a second. When you have 8 users, the test plan sends around 133 requests. It seems to work fine and nothing weird here.

When you have 8 users, JMeter would not have any issues in sending the first 8 requests (first request for each thread).But the subsequent requests for each thread will be sent only if the response is received for the previous request. (if you have any timers to simulate user think time,then the user will wait for the duration to send the next request after the response is received).

If 1 user is able to make 19 requests (or server processed 19 requests per second), then 8 users should be able to send 152 requests. But, when you increase the user load/increase the number of requests sent to the server, It's throughput (number of requests the server can process / unit time) will also increase gradually as shown in the picture. If you keep increasing the user, at one point, you would see the server's throughput (number of hits / second) gets saturated / would not increase beyond this point. So, may be, here the server got saturated at 133 requests / second. That is why we could not see 152 requests for 8 users. To understand the behavior, you need to increase user (ramp up) slowly.

Check here for few tips on JMeter

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