Data connection pool(数据连接池）

introduction

1. The data connection pool is a cache of database connection ,it will be reused when future requests to the database are required.
2. Because every connection of database is worth.If one connection of database ,the connection pool can save this connection information,so that next time it can connect quickly and improve enhance the database performance.
3. And the connection pool can manage the connections.If want to cut ,can do it.
   reference
   reference1 for Chinese