title: filesize not update after change file
body: <p>PHP code</p>
  
  <pre><code>echo filesize("a.jpg")."&lt;br/&gt;";
  
  imagejpeg(imagecreatefromjpeg("a.jpg"), "a.jpg", 50);
  
  echo filesize("a.jpg");
  </code></pre>
  
  <p>Output</p>
  
  <pre><code>73104
  73104
  </code></pre>
  
  <p>I have change quality of image but <code>filesize</code> not changed!!!</p>
  
  <p>However, the file size changed?!
  <a href="https://i.stack.imgur.com/hVxiK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hVxiK.png" alt="enter image description here"></a></p>
  
  <p>why function <code>filesize</code> not updated immediate after change file?</p>
  
  <p>My image(size 72k)
   <a href="https://i.stack.imgur.com/zcLW8.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zcLW8.jpg" alt="enter image description here"></a></p>