title: Why does the built-in metric "vus" in .json output not reflect the console output?
body: <p>In the console output of K6 you can easily see how many VUs are currently active.
  See picture <img src="https://i.stack.imgur.com/n3YV1.png" alt="k6 console output" /></p>
  <p>In the .json output there is a metric &quot;vus&quot; and a metric &quot;vus_max&quot;.
  I would expect &quot;vus&quot; to reflect the number of currently active virtual users.
  However, in my .json output, except for the entries where &quot;vus&quot; is 0, &quot;vus&quot; and &quot;vus_max&quot; always have the same value. See picture <img src="https://i.stack.imgur.com/2zG3l.png" alt="k6 .json output" /></p>
  <p>Is this a bug?
  If not, how to generate the correct number of active VUs in the .json output?</p>