title: Why is the MongoDB Node Driver generating instance pool destroyed errors?
body: <p>When I run the following code I am getting the error message '<strong>MongoError: server instance pool was destroyed</strong>'.  Any idea why or how to fix this?</p>
  
  <pre><code>var csv = require('./importer.js');
  var MongoClient = require('mongodb').MongoClient;
  var assert = require('assert');
  var ObjectId = require('mongodb').ObjectID;
  var url = 'mongodb://.....';
  
  
  MongoClient.connect(url, function(err, db) {
  
      assert.equal(null, err);
      console.log("Connected correctly to server.");
  
      csv.foreach('data/airports.csv', function(airport){
          db.collection('airports').insertOne(airport, function(err, result) {
              if(err) {
                  console.log(err)
              } else {
                  console.log("Inserted: " + airport.ident);
              }
          });
      });
  
      db.close();
  });
  </code></pre>