How to invoke scenarios using constant-arrival-rate executor

Grafana k6 OSS Support
1

Hi,

I am trying to use k6 for load testing some APIs. I want to generate a pattern of calling different APIs concurrently and controlling the rate for each one of them. I tried using the “constant-arrival-rate” executor but it didn’t work the way I expected it to, may be my understanding is wrong. Can someone please take a look at my script below and help me understand what I’m doing wrong here:

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

export let options = {
    //discardResponseBodies: true,
    scenarios: {
        testAPI1: {
            //set traffic pattern
            executor: 'constant-arrival-rate',
            rate: 1,
            timeUnit: '1s',
            duration: '60s',
            preAllocatedVUs: 1,
            maxVUs: 30
        },
        testAPI2: {
            //set traffic pattern
            executor: 'constant-arrival-rate',
            rate: 2,
            timeUnit: '1s',
            duration: '60s',
            preAllocatedVUs: 2,
            maxVUs: 30
        },
        testAPI3: {
            //set traffic pattern
            executor: 'constant-arrival-rate',
            rate: 3,
            timeUnit: '1s',
            duration: '60s',
            preAllocatedVUs: 3,
            maxVUs: 30
        }
    }
};

let appUrl = 'https://myAppUrl';

export function testAPI1() {
    let path = '/API1';

    http.get(appUrl + path);
}

export function testAPI2() {
    let path = '/API2';

    http.get(appUrl + path);

}

export function testAPI3() {
    let path = 'testAPI3';

    http.get(appUrl + path);
}

export default function() {
    console.log("in default");
}

I expected the above script to generate a concurrent call pattern as given below:

  • Call API1 @ rate of 1 request per sec for 60 secs.
  • Call API2 @ rate of 2 requests per sec for 60 secs.
  • Call API3 @ rate of 3 requests per sec for 60 secs.

But, what I am observing is that scenarios/functions testAPI1, testAPI2 and testAPI3 are not getting invoked. The default function keeps getting called in every iteration.

2

Hi @guneet,
The names of the scenarios don’t really have a lot of meaning, the way to specify which functions should be called is the exec option ;).

So in your case above you just defined 3 scenarios that by default have exec set to default, so that is what will be called ;). After this you can even drop the default function.