title: Why is the callback called at almost the same time when the readFile is called in a loop?
body: <pre class="lang-js prettyprint-override"><code>var fs = require('fs')
  function test() {
      for(let i=0; i&lt;10   ; i++) {
          console.time(i)
          fs.readFile(`test2.txt`, function out(err, data) {
              if(err) {
                  return console.error(err)
              }
              console.timeEnd(i)
          })
          
      }
  }
  
  test()
  </code></pre>
  <p>output:</p>
  <blockquote>
  <p>6: 114.242ms</p>
  <p>2: 120.270ms</p>
  <p>1: 120.644ms</p>
  <p>4: 120.946ms</p>
  <p>9: 121.326ms</p>
  <p>0: 122.458ms</p>
  <p>7: 121.973ms</p>
  <p>3: 122.365ms</p>
  <p>8: 122.652ms</p>
  <p>5: 123.059ms</p>
  </blockquote>
  <p>When I increase the number of loops, the print time for all callbacks is almost the same.</p>