title: Rails connection pool size for WEBrick
body: <p>I am getting </p>
  
  <pre><code>ActiveRecord::ConnectionTimeoutError (could not obtain a database connection within 5 seconds (waited 5.000798 seconds). The max pool size is currently 1; consider increasing it.)
  </code></pre>
  
  <p>when I try to run WEBrick (rails server) with the pool size 1, and no problems with higher pool sizes.</p>
  
  <p>What does WEBrick use the first connection on, and what is the best pool size for a single-threaded application? Is this a WEBrick-specific issue, or it applies to any other servers (like Unicorn)?</p>
  
  <p>Rails version is 3.2.13</p>
  
  <p>Update. Just verified this with unicorn, it works fine with single connection.</p>