When starting up Tomcat (6.0.26 or higher) , the log file reports Catalina started with no issues:
When shutting down Tomcat - Catalina reports multiple threads have failed to stop:
There is a memory leak detection feature introduced in Tomcat 6.0.25 that attempts to log objects that have failed to be unregistered by webapps it hosts when they are stopped, and were forcibly unregistered by Tomcat. As Tomcat is forcibly removing these objects, it is not a serious concern that these log messages occur.
Despite their apparent severity, these log messages are benign and can be safely ignored.
There is no resolution at this time. There is an improvement request to reduce these harmless messages in the log during Confluence shutdown which is being tracked at CONF-22879 - Reduce errors logged when shutting down Confluence Open .
This workaround is not recommended as Tomcat 6.0.20 has known performance issues, and has several security vulnerabilities. We recommend customers upgrade to (or continue to run) Tomcat 6.0.32 or higher.