DB连接池连不上，连接池耗尽

最近段时间。今年开始把。我维护的网站一直报错数据库连接不上，找不到链接，连接池耗尽问题。 
Caused by: org.apache.commons.dbcp.SQLNestedException: Cannot get a connection, pool exhausted 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:103) 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540) 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:81) 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:423) 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144) 
2017-07-26 15:42:20,516 ERROR [STDERR] at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:139) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1547) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.Loader.doQuery(Loader.java:673) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.Loader.loadEntity(Loader.java:1860) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3044) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:395) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:375) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:139) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:195) 
2017-07-26 15:42:20,531 ERROR [STDERR] at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:103) 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878) 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.hibernate.impl.SessionImpl.get(SessionImpl.java:815) 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.hibernate.impl.SessionImpl.get(SessionImpl.java:808) 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.springframework.orm.hibernate3.HibernateTemplate$1.doInHibernate(HibernateTemplate.java:477) 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:373) 
2017-07-26 15:42:20,547 ERROR [STDERR] ... 68 more 
2017-07-26 15:42:20,547 ERROR [STDERR] Caused by: java.util.NoSuchElementException: Timeout waiting for idle object 
2017-07-26 15:42:20,547 ERROR [STDERR] at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:756) 
大概日志如上所示，很是郁闷，叫来了测试。想让测试找出根源。结果测试只能重现错误。。我瞬间感觉失去信心了。 
后面好好看看日志，看看报错方法，发现dao里获取connection竟然是this.getSession。后面百度了下这个方法。是hibernate自带的，但不会释放。对比了几个获取方式，我小心翼翼的替换了几个类。害怕不是根源。。 
后面让测试再次测试了后。发现没有报错连接池耗尽之类的问题。。 
暂时这么处理了。后续在继续观察中。大家有更好的见解可以提出。