JMeter – Poisson Random Timer

JMeter - Poisson Random Timer

As the name suggested, JMeter Poisson Random Timer is used to generate and add the random delay before the execution of a sampler. This timer is based on the Poisson Distribution Function. The delay (think) time is the sum of the Poisson distributed value multiplied by defined lambda value and the offset value.

How to add ‘Poisson Random Timer’?

Follow the below steps:

  1. Select the appropriate element where you want to add the timer
    1. Test Plan
    2. Thread Group
    3. Controller
    4. Sampler
  2. Right-click on the element
  3. Hover the mouse on ‘Add’
  4. Hover the mouse on ‘Timers’
  5. Click ‘Poisson Random Timer’

What are the inputs for ‘Poisson Random Timer’?

‘Poisson Random Timer’ has the following input fields:

  1. Name: To provide the name of the timer
  2. Comments: To provide arbitrary comments (if any)
  3. Lambda (in milliseconds): The number shows how much the delay can deviate from the given offset towards the higher and lower range. 
  4. Constant Delay Offset (in milliseconds): The number shows a constant delay which will be added to the random number generated by Poisson Function in the range of given deviation value.

Example:

If Constant Delay Offset is given 1000 and Lambda is given 200 then Poisson Random Timer will generate the random number in the range of 800 to 1200 milliseconds:

Poisson Random Timer Delay = 1000 + PF*200   

where PF value could be from -1 to 1

JMeter - Poisson Random Timer
Figure 01

Additional Information:

  • The Poisson Random timer is processed before each sampler in the scope in which it is found; if there are several timers in the same scope, all the timers will be processed before each sampler.
  • Timers are only processed in conjunction with a sampler. A timer which is not in the same scope as a sampler will not be processed at all.
  • To apply the timer to a single sampler, add the Poisson Random Timer as a child element of the sampler.
  • To apply the timer after a sampler, either add the Poisson Random Timer as a child element of the next sampler or as a child element of Flow Control Action.

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