Siphalor/tweed5-commons-logging
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git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@370738 13f79535-47bb-0310-9956-ffa450edef68
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Simon Kitching
2006-01-20 05:53:42 +00:00
parent d7d7ac9454
commit 0077ddf3cd
1 changed files with 27 additions and 0 deletions
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src/java/org/apache/commons/logging/impl/ServletContextCleaner.java
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@@ -68,6 +68,33 @@ public class ServletContextCleaner implements ServletContextListener {
// Walk up the tree of classloaders, finding all the available
// LogFactory classes and releasing any objects associated with
// the tccl (ie the webapp).
//
// When there is only one LogFactory in the classpath, and it
// is within the webapp being undeployed then there is no problem;
// garbage collection works fine.
//
// When there are multiple LogFactory classes in the classpath but
// parent-first classloading is used everywhere, this loop is really
// short. The first instance of LogFactory found will
// be the highest in the classpath, and then no more will be found.
// This is ok, as with this setup this will be the only LogFactory
// holding any data associated with the tccl being released.
//
// When there are multiple LogFactory classes in the classpath and
// child-first classloading is used in any classloader, then multiple
// LogFactory instances may hold info about this TCCL; whenever the
// webapp makes a call into a class loaded via an ancestor classloader
// and that class calls LogFactory the tccl gets registered in
// the LogFactory instance that is visible from the ancestor
// classloader. However the concrete logging library it points
// to is expected to have been loaded via the TCCL, so the
// underlying logging lib is only initialised/configured once.
// These references from ancestor LogFactory classes down to
// TCCL classloaders are held via weak references and so should
// be released but there are circumstances where they may not.
// Walking up the classloader ancestry ladder releasing
// the current tccl at each level tree, though, will definitely
// clear any problem references.
ClassLoader loader = tccl;
while (loader != null) {
// Load via the current loader. Note that if the class is not accessable