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Documentation Grafana k6 Using k6 Workaround to calculate iteration_duration

Workaround to calculate iteration_duration

A common requested case is to track the iteration_duration metric without including time spent for setup and teardown functions. This feature is not yet available but a threshold on iteration_duration or any pre-existing metrics can be used as a workaround.

It’s based on the concept of creating thresholds for sub-metrics created by tags for the required scope and setting the criteria that always pass. It works with any enabled tags that already works with threshold, for example:

• iteration_duration{scenario:default} generates a sub-metric collecting samples only for the default scenario’s iteration. scenario:default is used because that’s the internal k6 scenario name when we haven’t specified options. scenarios` explicitly and are just using the execution shortcuts instead.
• iteration_duration{group:::setup} or iteration_duration{group:::teardown} create sub-metrics collecting the duration only for setup and teardown. k6 implicitly creates groups for setup and teardown, and :: is the group separator.
• http_req_duration{scenario:default} can be useful as well for isolating executed long-running requests.

JavaScript

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import { sleep } from 'k6';
import http from 'k6/http';

export const options = {
  vus: 1,
  iterations: 1,
  thresholds: {
    'iteration_duration{scenario:default}': [`max>=0`],
    'iteration_duration{group:::setup}': [`max>=0`],
    'iteration_duration{group:::teardown}': [`max>=0`],
    'http_req_duration{scenario:default}': [`max>=0`],
  },
};

export function setup() {
  http.get('https://quickpizza.grafana.com/api/delay/5');
}

export default function () {
  http.get('http://test.k6.io/?where=default');
  sleep(0.5);
}

export function teardown() {
  http.get('https://quickpizza.grafana.com/api/delay/3');
  sleep(5);
}

Dedicated sub-metrics have been generated collecting samples only for the scope defined by thresholds:

bash

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  █ THRESHOLDS

    http_req_duration{scenario:default}
    ✓ 'max>=0' max=117.34ms

    iteration_duration{group:::setup}
    ✓ 'max>=0' max=0s

    iteration_duration{group:::teardown}
    ✓ 'max>=0' max=0s

    iteration_duration{scenario:default}
    ✓ 'max>=0' max=1.13s