Tomcat连接池创建了太多连接，处于休眠模式

I'm using Tomcat 6.0.29, with Tomcat 7's connection pool and MySQL. Testing my application, it doesn't reuse anything from the pool, but ends up creating a new pool, to eventually where I cannot use the database because there are hundreds of sleeping connections in the pool when the max active size for the pool is set to 20. I'm using Tomcat 6.0.29, with Tomcat 7's connec