In Arrivals Thread Group, with the below settings, in Graph arrival Rate displayed is ~330.
Target rate : 120 Ramp -up : 1 Ram-up step count: 2 Hold the target time: 2
In Free-Form Arrivals Thread Group; in Graph arrival Rate displayed is ~600
Start Value 20 End Value 0 Duration 60
In both the thread how arrival Rate calculated.
According to above settings:
Target Rate: 120 arrivals in a minute means there will be two arrival per second. Each second JMeter will kick off two virtual users which will be executing samplers.
Ramp-up time: the time which will be taken to reach the target rate, i.e. JMeter starts from zero arrivals per minute and increases the arrivals rate to 120 arrivals per minute in 60 seconds.
Ramp-up steps: here you can set the “granularity” of increasing arrivals rate, more steps - more smooth pattern, fewer steps - you will have “spikes”
Hold Target Rate: it will keep the threads in steady state for the duration specified. In your case, it will keep a number of threads 120 for the end of the run. As explained in above comment.
So according to settings, JMeter will ramp-up from 0 to 2 arrival per second in one minute plus run the test for 2 minutes.
If I have 1 sampler in Test Plan it will be something like 330. executions, if I have 2 samplers - 330. executions per sampler, in total 660 executions. Approximate request rate will be 110 requests/minute.
For Free Form Arrivals Thread Group
Start Value: Means arrival rate at the beginning of the test
End value: Means Arrival Rate at the end of test..
Duration : Test Duration
lets say the test duration is for 60 seconds
Jmeter will start with 20 executions per second and gradually it will be reduced to zero by the end of 60 seconds , That means for every 3 seconds arrivals rate will be decreased by 1. So if we calculate the total arrivals rate executions 20 executions for the first 3 seconds 19 for the next 3 18 for the next 3 and so on.... adding up all the executions it will be approximately 600 executions per 60 seconds..
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For arrivals thread group Lets break our test into 3 parts.. 1.0-30 seconds 2.30-60 seconds 3.60-180 seconds.
Totals Arrivals = Arrivals between 0-30 sec + Arrivals between 30-60 sec + Arrivals between 60-180 sec
Now in the test plan ramp up steps 2 and ramp up rate is 1 minute That means 120 arrivals per minute is reached in 1 minute with 2 steps (30 seconds each) So for the first 30 seconds arrival rate would be 60 arrivals per minute and number of arrivals for 30 seconds @60 arrivals per minute is 30 (As its runninig for 30 seconds ).
For 30-60 seconds the arrival rate is 120 and number of arrivals for 30 seconds @120 arrivals per minute is 60 (120*30/60=60) arrivals
For 60-180 seconds the arrival rate is 120 arrvals per minute so for 2 minutes the total arrivals is 120*2=240 arrivals.
So total number of arrivals = 30+60+240 = 330
For Free form arrivals thread group
the arrivals rate is gradually reduced to zero in 60 seconds That means for every 3 seconds the rate is decreased by one
so the total number of arrivals for 0- 3 seconds is 20 + 20 +20 total number of arrivals for 3- 6 seconds is 19+ 19+19 and so on..
Adding up all arrivals (20*3+19*3+...+1*3)=630
