title: MongoDB too many open connections when auto reconnect
body: <p>I'm creating api server using nodejs+mongodb (mongodb-native). My app are open connection only one time and reuse it.</p>
  
  <p>When my app connected to database (mongod log)</p>
  
  <pre><code>2015-07-28T02:28:06.485+0700 I NETWORK  [conn3] end connection 127.0.0.1:62621 (0 connections now open)
  2015-07-28T02:28:06.486+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:62622 #4 (1 connection now open)
  2015-07-28T02:28:06.488+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:62623 #5 (2 connections now open)
  2015-07-28T02:28:06.488+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:62624 #6 (3 connections now open)
  2015-07-28T02:28:06.491+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:62625 #7 (4 connections now open)
  2015-07-28T02:28:06.491+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:62626 #8 (5 connections now open)
  </code></pre>
  
  <p>"5 connections now open" Ok It's correctly.</p>
  
  <p>Then I'm try to shutdown mongod for 10 seconds then start mongod again.</p>
  
  <pre><code>2015-07-28T02:30:39.533+0700 I NETWORK  [conn22] end connection 127.0.0.1:63002 (21 connections now open)
  2015-07-28T02:30:39.534+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:63003 #23 (22 connections now open)
  2015-07-28T02:30:39.538+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:63004 #24 (23 connections now open)
  2015-07-28T02:30:39.538+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:63005 #25 (24 connections now open)
  2015-07-28T02:30:39.538+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:63006 #26 (25 connections now open)
  2015-07-28T02:30:39.539+0700 I NETWORK  [initandlisten] connection accepted from 127.0.0.1:63007 #27 (26 connections now open)
  </code></pre>
  
  <p>"26 connections now open" Something wrong?</p>
  
  <p>here is my connection options</p>
  
  <pre><code>options: {
          server: {
              poolSize: 5,
              auto_reconnect: true,
              reconnectTries: -1,
              reconnectInterval: 1000,
          }
      }
  </code></pre>
  
  <p>This is problem or not? How to fix it?</p>