Therefore, one should check that the ClassLoader for each driver is the webapp's ClassLoader before deregistering it. Deregistering these will affect any other webapps which may be using them (or even the container itself). Some drivers returned by the DriverManager.getDrivers() method may have been loaded by the parent ClassLoader (i.e., the servlet container's classloader) not the webapp context's ClassLoader (e.g., they may be in the container's lib folder, not the webapp's, and therefore shared across the whole container). However, the methodology of blanket driver deregistration is dangerous. For example HikariCP or perhaps Tomcat JDBC Pool.Īlthough Tomcat does forcibly deregister the JDBC driver for you, it is nonetheless good practice to clean up all resources created by your webapp on context destruction in case you move to another servlet container which doesn't do the memory leak prevention checks that Tomcat does. You would rather like to replace DBCP by another connection pool which is doing its job better then DBCP. See also bug DBCP-322 which is closed as WONTFIX. Note that Tomcat's builtin DBCP does not deregister drivers properly on close. Move the JDBC driver to Tomcat's /lib folder and have a connection pooled datasource to manage the driver.

Those kind of memory leaks are one of the major causes behind OutOfMemoryError issues during Tomcat hotdeployments. Not sure if that's good to know after all. But it will silently keep leaking memory. If you still keep it in webapp's /WEB-INF/lib, then you should manually register and deregister it using a ServletContextListener.ĭowngrade to Tomcat 6.0.23 or older so that you will not be bothered with those warnings. On the other hand, you aren't supposed to drop a JDBC driver in webapp's /WEB-INF/lib, but only in server's /lib. Be happy that Tomcat did its job properly and wait until the JDBC driver vendor get it fixed so that you can upgrade the driver. The actual bug is in someone else's code (the JDBC driver in question), not in yours.

This message is purely informal, Tomcat has already taken the memory leak prevention action accordingly. Since version 6.0.24, Tomcat ships with a memory leak detection feature, which in turn can lead to this kind of warning messages when there's a JDBC 4.0 compatible driver in the webapp's /WEB-INF/lib which auto- registers itself during webapp's startup using the ServiceLoader API, but which did not auto- deregister itself during webapp's shutdown.

Callnote crashes on startup