Work Load Modelling using concurrent Vusers and Transactions Per Hour (TPH)

One of the important aspects of performance testing is Work Load Modelling (WLM) and in this article we will see how we can design it based on the below inputs from the client.

•        800 concurrent vusers
•        TPH is 25% of TPD (Transactions Per Day). Script wise TPD has been shared by the client.
•        Duration of the test will be 1 hour (3600 Seconds).

Now let’s see how we can design the WLM.

Below table shows the final WLM we have arrived at. In a step by step manner we will see how we calculated each parameter.

Step 1 – Calculate TPH

We know that TPH is 25 % of TPD. So our TPH will be.

TPH = 0.25 X TDP.

Step 2 – Calculate Load Distribution %

To find out the load distribution for each script, we need the Total TPH which will be the sum of all the scripts TPH. So our Load Distribution % will be.

Total TPH = ∑ TPH

Load Distribution % = (Script TPH / Total TPH) X 100

Load Distribution % value will be in decimal and we need to round it off.

Step 3 – Calculate Vusers

We know from the requirement, the Total Concurrent Vusers for the scenario will be 800. Now we need to distribute this across the scripts based on the scripts Load Distribution %. So our Vusers will be.

Vusers = (800 X Load Distribution %) / 100

Step 4 – Calculate Pacing

We know that the duration of the test will be 3600 seconds. So we will set the duration of the run in the controller and we will calculate only pacing so that the controller will decide upon the iterations required to achieve the TPH.  Since we know Vusers & TPH, our Pacing will be.

Pacing = (Vusers X Duration of the test in Seconds) / TPH