title: Get number of busy CPUs in Python
body: <p>I am writing a <code>multiprocessing</code> routine to run on a server with plenty of CPUs. However, the server has multiple users and its usage may vary. So I would like to adapt the number of processors being used according to the current load.</p>
  
  <ul>
  <li>Is there a way to estimate the amount of CPUs currently busy in Python? I only found <code>multiprocessing.cpu_count()</code></li>
  <li>Bonus question: Is it possible to change <code>multiprocessing.Pool(processes=no_cpus)</code> during activity, in case the load on the server has changed after a while?</li>
  </ul>