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https://issues.apache.org/jira/browse/DBCP-332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12870567#action_12870567
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Grzegorz Borkowski commented on DBCP-332:
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I've discovered one problem with unregistering SQL driver in
BasicDataSource.close() method: if you create the BasicDataSource, retrieve
connection, close connection, than close BDS, and than create new instance of
BDS, and try to obtain connection, it will not work: it will complain that it
can't find proper driver for given URL. I haven't had time to investigate it,
but I guess that driver registration is done somehow statically, at class
loading. So after you deregister driver and create new instance of BDS, driver
is not registered again, because no classlodin is done at that moment. That's
my guess at least. As a solution, the BDS could try to register manually the
driver (using java.sql.DriverManager.registerDriver) whenever first attempt to
obtain driver fails.
> Closing BasicDataSource doesn't deregister JDBC driver, causing memory leak
> ---------------------------------------------------------------------------
>
> Key: DBCP-332
> URL: https://issues.apache.org/jira/browse/DBCP-332
> Project: Commons Dbcp
> Issue Type: Bug
> Affects Versions: 1.3, 1.4
> Reporter: Grzegorz Borkowski
> Fix For: 1.3.1, 1.4.1
>
>
> BasicDataSource's method close() doesn't deregister JDBC driver. This causes
> permgen memory leaks in web server environments, during context reloads. For
> example, using Tomcat 6.0.26 with Spring, and BasicDataSource declared in
> Spring context, there is a message printed at web application reload:
> SEVERE: A web application registered the JBDC driver [com.mysql.jdbc.Driver]
> but failed to unregister it when the web application was stopped. To prevent
> a memory leak, the JDBC Driver has been forcibly unregistered.
> I was able to fix it by overriding close method this way:
> {code}
> public class XBasicDataSource extends BasicDataSource {
> @Override
> public synchronized void close() throws SQLException {
> DriverManager.deregisterDriver(DriverManager.getDriver(url));
> super.close();
> }
> }
> {code}
> but I think it should be probably the default behavior of BasicDataSource. Or
> perhaps there should be some flag/setting on BasicDataSource, named
> "deregisterDriverAtClose" or so.
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