Number of requests sent by K6 as per the test seems to be dropping in between during the total test duration

Setup:

I am currently running my k6 test in a container(4 cpu, 16Gig mem) which I ran by building the xk6 image using the Dockerfile mentioned xk6-output-influxdb/Dockerfile at main · grafana/xk6-output-influxdb · GitHub

I am collecting and sending the metrics to InfluxDb using xk6 and then plotting a graph of requests/sec in grafana.

Test file

I am running the following test against a server

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

export const options = {
  scenarios: {
    cs: {
      executor: 'constant-vus',
      vus: 2,
      duration: '60s',

      // stages: [
      //   { duration: '10s', target: 10 },
      //   { duration: '50s', target: 10 },
      //   { duration: '10s', target: 0 },
      // ]
    }
  }
};

export default function () {
  const url = 'http://ai-gateway-influx:5052/v2/code/completions'; // Replace with your API endpoint
  const payload = JSON.stringify({
    "project_path": "string",
    "project_id": 0,
    "current_file": {
      "file_name": "test",
      "language_identifier": "string",
      "content_above_cursor": "func hello_world(){\n\t",
      "content_below_cursor": "\n}"
    },
    "stream": true,
    "choices_count": 0,
    "context": [],
    "prompt_id": "code_suggestions/generations",
    "prompt_version": 2
  });

  const params = {
    headers: {
      'Content-Type': 'application/json',
    },
  };

  const res = http.post(url, payload, params);

  check(res, {
    'status is 200': (r) => r.status === 200,
    'response time < 500ms': (r) => r.timings.duration < 500,
  });

  const utcTimestamp = new Date().toISOString();
  const message = `{"pe_iteration":"${__ITER}", "pe_http_method": "${res.request.method}", "pe_http_url": "${res.request.url}", "pe_http_status": "${res.status}", "pe_response_duration": "${res.timings.duration}ms", "pe_utc_timestamp": "${utcTimestamp}"}` 

  console.log(JSON.parse(message))
  sleep(1);
}

Actual Results: When I run the tests, I can see that intermittently, the number of requests go down and then come back up again.

Expected Result: I would expect the load that is being generated by k6 to be constant.

You can see in the below logs that there is no log entry for 2025-01-21T01:15:56 but there is one for 2025-01-21T01:15:55 and another for 2025-01-21T01:15:57

You can also see this drop which is pretty obvious in the Grafana dashboard. In this case it dropped to 0 from 2rps but when I tried for more VUs like 20 it used to drop to say 7/8/other lower value and then back to 20.

In case you are wondering the query I used for grafana

from(bucket: "test")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r._measurement == "http_reqs")
  |> aggregateWindow(every: 1s, fn: count)

I also tried increasing the container capacity by increasing the CPU and memory but to no avail. I can still see requests dropping in between during the duration of the test.

Can you help me figure out why this is the case?

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