var MongoClient = require('mongodb').MongoClient
  , f = require('util').format;

MongoClient.connect('mongodb://localhost:27017/test', {db: {native_parser: true, bufferMaxEntries: -1},
        server: {
            poolSize: 20,
            socketOptions: {autoReconnect: true, keepAlive: 50},
	    reconnectTries : 1000,
	    reconnectInterval : 1000
        }}, function(err, db) {
  var col = db.collection('t');
  var count = 1;
 setInterval(function() {
    col.insertOne({a:1, count: count}, function(err, r) {
      console.log("insert", count)
      console.log(err);
	 count = count + 1;
      col.findOne({}, function(err, doc) {
        console.log("findOne")
        console.log(err)
      });
    })
  }, 2000)
});