code: def get_mysql_pool(host=None, user=None, password=None, charset='utf8', 
          db=None, size=None, isSync=True, ioloop=None):
      
      factory = mysql_pool_factory(isSync)
      kwargs = {
          'host': host,
          'user': user,
          'password': password,
          'charset': charset,
          'db': db,
          'size': size,
      }
      return factory(**kwargs)
docs: 使用工厂方法返回一个连接池