title: MongoDb MapReduce creating bottleneck for Database queries
body: <p>In my project, I am using mongodb MapReduce for data aggregation and some heavy calculations on the aggregated results in Finalize function.</p>
  
  <p><strong>Issue faced:</strong>
  If any MR job is in process than somehow for all the users the number of database requests / queries is getting limited to 2 - 3 per client. Any extra db query request (from the same client) is not entertained and user gets stuck. 
  If any other user sends a http request or db query request (single OR max 2 -3 db requests) to node server it works fine. So it implies that my node loop is not blocked. Note that I am using only single node process (clusters are not yet used).</p>
  
  <p>After the MR job completes, everything works fine and the pending database queries returns successfully.</p>
  
  <p>To ensure that nothing is wrong with my project, I created a simple node project without express and mongoose and run a similar test on it. Issue was easily reproducible in that as well.</p>
  
  <p>Any reason why this is happening ?</p>
  
  <p>Any help would be appreciated.</p>