var http = require(‘http’); var mongodb = require(‘mongodb’); var poolModule = require(‘generic-pool’);

	  var pool = poolModule.Pool({
		  name: 'mongodb',
		  create: function(callback) {
			  mongodb.MongoClient.connect('mongodb://localhost/test', {
				  server: {poolSize: 10}
			  }, function(err, db) {
				  callback(err, db);
			  });
		  },
		  destroy: function(db) {
			  db.close();
		  },
		  max: 100,
		  idleTimeoutMillis: 30000,
		  log: false
	  });
	  
	  http.createServer(function(req, res) {
		  pool.acquire(function(err, db) {
			  if (err) {
				  res.statusCode = 500;
				  res.end(JSON.stringify(err, null, 2));
			  } else {
				  db.collection('userinfo').save({name: 'jack'}, function(err, result) {
					  res.end(JSON.stringify(result, null , 2));
					  pool.release(db);
				  });
			  }
		  });
	  }).listen('8888');
	  console.log('this server is listening on port 8888...');
	  
	  
	  setTimeout(function() {
		  for (var i = 0; i < 1000; i++) {
			  http.get('http://localhost:8888', function(res) {
				  console.log('request ok...');
			  });
		  }
	  }, 2000);
错误信息：
events.js:85
	  throw er; // Unhandled 'error' event
			^
Error: connect ECONNREFUSED
	at exports._errnoException (util.js:746:11)
	at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1000:19)