title: Is spawning threads inside of threads standard or bad practice?
body: <p>In short: Is spawning threads inside of threads a standard procedure or should this be avoided if possible?</p>
  
  <p>An example: Think of a parallel spider retrieving and parsing multiple documents at once.
  In my reasoning the spider in question would need two threads(FetcherPool, ParserPool) spawning Fetcher- and Parser worker threads in order to make everything work concurrently(see below).</p>
  
  <p>Example:</p>
  
  <pre><code>Main Thread  
  |------FetcherPool  
  |      |------Fetcher  
  |      |------Fetcher  
  |  
  |------ParserPool 
         |------Parser  
         |------Parser  
  </code></pre>
  
  <p>Cheers</p>