数据库连接池在编写应用服务是经常需要用到的模块，太过频繁的连接数据库对服务性能来讲是一个瓶颈，使用缓冲池技术可以来消除这个瓶颈。-database connection pool in the preparation of application services is often necessary to use modules, too busy to connect to the database in terms of service performance is a bottlenec