title: Understanding Rob Pike's book incineration example
body: <p>In Rob Pike's talk 2012 talk, <a href="https://blog.heroku.com/archives/2013/2/24/concurrency_is_not_parallelism" rel="nofollow noreferrer">Concurrency is not Parallelism (it's better)</a>, he has a running examples of a group of gophers working together to incinerate a pile of books.</p>
  
  <p>On slide 15 (<a href="http://www.youtube.com/watch?v=cN_DpYBzKso&amp;t=6m58s" rel="nofollow noreferrer">video 6:58</a>), there are three gophers at work: </p>
  
  <ol>
  <li>One loading books from a pile into a cart.</li>
  <li>One moving the filled cart to the incinerator (and later returning the empty cart).</li>
  <li>One moving the books from the cart into the incinerator.</li>
  </ol>
  
  <p><img src="https://i.stack.imgur.com/GAj2g.png" alt="3 gophers working together to burn books"></p>
  
  <p>On <a href="http://concur.rspace.googlecode.com/hg/talk/concur.html#slide-16" rel="nofollow noreferrer">slide 16</a>, four gophers are working together on the same problem:</p>
  
  <ol>
  <li>One loading books from a pile into a cart (as before).</li>
  <li>One moving the filled cart to the incinerator.</li>
  <li>One moving the books from the cart into the incinerator (as before).</li>
  <li>One moving the empty cart back to the pile.</li>
  </ol>
  
  <p><img src="https://i.stack.imgur.com/QjsGt.png" alt="4 gophers working together to burn books">
  Pike says that this performs more work but will run faster.  Why?  It seems like the same amount of work, shared by more gophers.</p>