Real users pause between actions -- they read a page, fill out a form, or decide what to click next. A think time command inserts these pauses into your stress testing scenario so that virtual users behave realistically instead of firing requests at machine speed.
PTS supports three timer types:
| Timer type | Behavior | Best for |
|---|---|---|
| Fixed | Waits exactly N milliseconds | Predictable, repeatable delays |
| Uniform Distribution | Waits a random duration within a defined range; every value in the range is equally likely | Varied but bounded user behavior |
| Normal Distribution | Waits a random duration clustered around a central value (Gaussian) | Realistic modeling where most delays fall near an average |
Add a think time command to a scenario
Log on to the PTS console. Choose Performance Test > Create Scenario, and then click PTS.
On the Scenario Settings tab of the Create PTS Scenario page, configure basic request information for an HTTP node.
Click the drop-down arrow to the right of Add Instruction and select Think Time.
In the Think Time row, click the drop-down arrow and configure the Timer Type and Latency parameters. See the following sections for details on each timer type.
Timer types
Fixed
The request pauses for exactly N milliseconds before continuing. N is the value you set in the Latency field.
For example, setting the latency to 3000 makes every virtual user wait exactly 3 seconds between the preceding request and the next action.
Uniform Distribution
The request pauses for a random duration uniformly distributed across the range [Delay offset, Delay offset + Changeable span]. Every value in this range is equally likely.
| Parameter | Description |
|---|---|
| Delay offset | The minimum pause duration (in milliseconds) |
| Changeable span | The size of the random range added to the delay offset |
Delay formula: actual delay = random value in [Delay offset, Delay offset + Changeable span]
For example, if you set Delay offset to 3 and Changeable span to 2, the pause duration is randomly selected from 3, 4, or 5 milliseconds for each request.
Normal Distribution
The request pauses for a random duration that follows a normal distribution (Gaussian distribution). Configure two parameters:
| Parameter | Description |
|---|---|
| Mean (mu) | The central value around which most pause durations cluster |
| Variance (sigma squared) | Controls the spread. A smaller variance keeps durations tightly grouped around the mean. A larger variance produces a wider range of durations. |
For example, setting a mean of 5000 and a small variance produces pauses that mostly fall close to 5 seconds, while a larger variance results in pauses that range more widely above and below 5 seconds.
Choose the right timer type
| Scenario | Recommended timer type | Example |
|---|---|---|
| Consistent, reproducible timing between requests | Fixed | Benchmarking a specific endpoint under a controlled cadence |
| Randomized delays within a strict range | Uniform Distribution | Simulating users who take between 2 and 5 seconds to read a confirmation message |
| Delays clustered around a typical value with natural variation | Normal Distribution | Modeling real user behavior where most pauses fall near an average think time |