title: MongoDB: What is connection pooling and timeout?
body: <p>So my Passenger spins up 5 instances of my Rails app</p>
  
  <p>I connect to MongoDB using Connection.new("localhost", 3000, :pool_size => 1, :timeout => 5)  </p>
  
  <p>Why would I need a "pool of connections" if I only incur overhead when starting up my Rails app, not per request? Why would a single process need more than 1 connection?  </p>
  
  <p>And what is the purpose of the timeout? Why would I want the connection to timeout? Shouldn't it be persist through the Rails process' lifetime? </p>
  
  <p>So confused... </p>
  
  <p>This question is specific to Ruby and Mongo but I guess it applies to other languages/databases.</p>