title: mongodb connection timed out error
body: <p>I have used mongodb database and node.js v12.0.10 for connecting and updating mongodb collection.
  connection code is the following:</p>
  
  <pre><code> async.parallel({
          RE5: function (cb) {
              MongoClient.connect(config.riskEngineDB, function (err, r5DB) {
                  cb(err, r5DB);
              })
          },
          MDB: function (cb) {
              MongoClient.connect(config.monitoringDB, function (err, mDB) {
                  cb(err, mDB);
              })
          }
      },
      function (err, DBs) {
          assert.equal(null, err);
          console.log("Connected correctly to Dbs");
          // ..doing updates..
  
   })
  </code></pre>
  
  <p>after some time running, script printed the following error:</p>
  
  <pre><code>  { [MongoError: connection 39 to 127.0.0.1:27017 timed out]
    name: 'MongoError',
    message: 'connection 39 to 127.0.0.1:27017 timed out' }
  </code></pre>
  
  <p>For your information, I used different options of connections of mongodb but it didn't make sense.</p>