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)