当我使用Tomcat 7 JDBC连接池取消部署webapp时，为什么连接仍然存在？

Question

I've got a minimal Spring webapp deployed to Tomcat 7.0.22 - it consists of a couple of pages, a controller, a service, and a DAO which has one method that runs a SELECT query.

The webapp is configured to use the new Tomcat JDBC connection pool - here is the resource configuration in the webapp's context.xml:

<Resource name="jdbc/myDB"
          auth="Container"
          type="javax.sql.DataSource"
          driverClassName="oracle.jdbc.OracleDriver"
          url="jdbc:oracle:thin:@blah blah"
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          maxActive="15"
          initialSize="5"
          maxWait="40000"
          validationQuery="select 1 from dual"
          removeAbandoned="true"
          removeAbandonedTimeout="300"
          logAbandoned="false"
          username="user"
          password="pass"
          testOnBorrow="true"
          validationInterval="30000"
          timeBetweenEvictionRunsMillis="60000"
          minEvictableIdleTimeMillis="60000" />

When I deploy the webapp I see 5 connections appear (querying v$session from SQL Developer). When I undeploy the webapp the connections persist (in state WAITING). Each time I redeploy my webapp, 5 new connections show up.

It appears the pool is still hanging around - and the "Find Leaks" button on Tomcat's manager app tells me the app is leaking memory.

How do I get rid of the pool when the webapp is undeployed?

Answer 1

The problem was self-inflicted (as most are). My data source was configured in my webapp's web.xml and I was referencing it via JNDI. I now create my data source as shown in the Spring reference doc ( section 13.3.1 ) and the destroy method takes care of closing the data source and pool.

If I'd been required to stick with a JNDI data source I would have had to close out the data source in a class that implements ServletContextListener , in the contextDestroyed method.

Answer 2

This is a behaviour reported in Apache Tomcat bugzilla, Reference:

https://issues.apache.org/bugzilla/show_bug.cgi?id=25060

It has been corrected from Tomcat 7.0.11. Which version of Tomcat have you been using ?

If you use create the datasource as described in the Spring reference at"application level", you would a little overhead when it comes to administration tasks if you have a lot of applications and many servers.

Answer 3

I had the same problem and I could not use spring so I used a org.apache.tomcat.jdbc.pool.DataSourceProxy to close a Tomcat Datasource. This API provides you with functionality not yet implemented JDK DataSource interface.

DataSourceProxy myDataSource = (DataSourceProxy) myDataSource;
myDataSource.close();   

• Also using factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" and a ServletListener contextDestroyed method.