What is Delay when running a Load Test?

What is Delay in a load test?

In a LoadFocus load test, Delay (ms) is the pause between the start of one virtual user and the start of the next. It staggers the users so they do not all send their first request at the same instant.

The new-test page does not show a Delay (ms) field, so you cannot change it there: new tests are saved with the default of 100 ms, and a test you edit keeps the delay it was saved with. To shape how the load builds up, use Ramp Up Time (s) in the How much load? step, and Ramp Up Steps under Fine-tune in the same step.

For example, with 50 virtual users and a delay of 100 ms, the users start one after another over about 5 seconds (50 x 100 ms).

Delay is not think time

Delay only spaces out the start of the virtual users. It does not add a pause between the requests a virtual user sends after it has started.

Delay and ramp-up time

Both settings shape how the load builds up, but they are different:

• Delay is the gap between one virtual user starting and the next.
• Ramp Up Time is how long it takes until all virtual users are running. See What is Ramp Up Time.
• Ramp Up Steps split that ramp-up into stages. See What is Ramp Up Steps.

A very short delay with many virtual users sends a burst of first requests at once. A longer delay gives the system under test time to warm up between starts.