[dialog2] Clean up static resources at application shutdown

• Key: SHALE-274
• Type: Bug
• Status: Resolved
• Resolution: Fixed
• Priority: Major
• Assignee: Unassigned
• Reporter: Craig McClanahan
• Component/s: Dialog
• Fix Version/s: 1.0.4

Description

The legacy dialog2 implementation relies on both Commons Logging and Commons Digester (which implies a transitive dependence on Commons BeanUtils). Therefore, we need to clean up at application shutdown by executing the following in a contextDestroyed() lifecycle listener (or equivalent):

    PropertyUtils.clearDescriptors();
    LogFactory.release(Thread.currentThread().getContextClassLoader());

Comments

[Craig McClanahan]

Further research, plus a pointer in the right direction from Niall Pemberton[1], illustrates that the above steps (while a good idea to avoid memory leaks) are not sufficient to avoid leaving shale-dialog-basic-xxxxx.jar locked when undeploying on Windows. There is an issue in Digester 1.6 and 1.7 (but fixed in recent nightly builds) when you use the Digester.register() method to register instances of (say) DTDs that are present inside your JAR file, so that the application does not have to go out to the Internet to resolve them. Released versions of Digester leave an I/O channel to the internal DTD open when it is used in this way, which prevents the JAR file from being closed on Windows. The latest Digester trunk code uses a workaround to avoid this problem.

[1] http://issues.apache.org/jira/browse/DIGESTER-29

[Craig McClanahan]

We depend on Commons Digester 1.8 now, so this issue has been completely dealt with.