解決Tomcat 6.0的This is very likely to create a memory leak.的錯誤訊息

砂拉豆

從Apache Tomcat 5.5升級到6.0，通常不用太大的修改，原有的Web Application就能繼續運作。不過在server.xml中設定MySQL Datasource，卻出現一串惱人的警告訊息：

2010/8/6 下午 01:54:11 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
嚴重的: The 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.
2010/8/6 下午 01:54:11 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
嚴重的: The web application [/] appears to have started a thread named [Timer-0] but has failed to stop it. This is very likely to create a memory leak.
2010/8/6 下午 01:54:11 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
嚴重的: The web application [/] appears to have started a thread named [MySQL Statement Cancellation Timer] but has failed to stop it. This is very likely to create a memory leak.

更新MySQL Connector/J至最新版也沒用，似乎是Tomcat 6.0對於Memory Leak的防範變得比較雞婆智慧，才會多了這樣的警告。

既然被列為嚴重程度的警告，當然就不能視而不見，解決的方法並不難，只是要把原本設定在區段中的搬到，修改方式如下。

1. 將<Resource name="jdbc/NAME" auth="Container" type="javax.sql.DataSource" ... /> 整塊剪下，再貼到 <GlobalNamingResources> ... </GlobalNamingResources> 之間。

2. 在原本Resource標籤的位置加入<ResourceLink global="jdbc/NAME" name="jdbc/NAME" type="javax.sql.DataSource" />

如此即可順利解決，其他設定不需要異動。