This is documentation for the next version of K6. For the latest stable release, go to the latest version.
Constant VUs
With the constant-vus
executor, a fixed number of VUs execute as many iterations as possible for a specified amount of time.
For a shortcut to this executor, use the VUs and duration options.
Options
Besides the common configuration options, this executor has the following options:
Option | Type | Description | Default |
---|---|---|---|
duration(required) | string | Total scenario duration (excluding gracefulStop ). | - |
vus | integer | Number of VUs to run concurrently. | 1 |
When to use
Use this executor if you need a specific number of VUs to run for a certain amount of time.
Example
This examples schedules 10 VUs to run constantly for a duration 30 seconds.
import http from 'k6/http';
import { sleep } from 'k6';
export const options = {
discardResponseBodies: true,
scenarios: {
contacts: {
executor: 'constant-vus',
vus: 10,
duration: '30s',
},
},
};
export default function () {
http.get('https://test.k6.io/contacts.php');
// Injecting sleep
// Total iteration time is sleep + time to finish request.
sleep(0.5);
}
Observations
The following graph depicts the performance of the example script:
Based upon our test scenario inputs and results:
- The number of VUs is fixed at 10, and are initialized before the test begins;
- Overall test duration is fixed at the configured 30 second duration;
- Each iteration of the
default
function is expected to be roughly 515ms, or ~2/s; - Maximum throughput (highest efficiency) is therefore expected to be ~20 iters/s,
2 iters/s * 10 VUs
; - We see that the maximum throughput is reached and maintained for the majority of the test;
- Approximately 600 iterations are therefore performed in total,
30 seconds * 20 iters/s
.