All,
Please check this thread for full details:
https://lists.apache.org/thread/of5ozg43zyk729cg311dktjcv3swct26
Briefly, a user reported this NPE:
Apr 29, 2023 5:41:32 PM org.apache.catalina.core.StandardContext
listenerStart
SEVERE: Exception sending context initialized event to listener instance
of class [org.springframework.web.context.ContextLoaderListener]
java.lang.NullPointerException
at
org.apache.catalina.loader.WebappClassLoaderBase$CombinedEnumeration.inc(WebappClassLoaderBase.java:2775)
at
org.apache.catalina.loader.WebappClassLoaderBase$CombinedEnumeration.hasMoreElements(WebappClassLoaderBase.java:2760)
at
org.apache.commons.logging.LogFactory.getConfigurationFile(LogFactory.java:1366)
at
org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:453)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:655)
Mark introduced the CombinedEnumeration in
https://github.com/apache/tomcat/commit/fdd35009ead6365cbae84008e63356d6ab88ed40
to merge the resources from the parent ClassLoader with the
WebappClassLoader(Base). His code looks sound to me, but it can expose
what I think of as a bug in the ClassLoader being used as the parent.
ClassLoader.getResources is documented to return an empty Enumeration if
there are no matching resources, but in this case, the ClassLoader is
returning null.
WebappClassLoaderBase assumes that the parent ClassLoader is following
the rules and so grabs the resources from both itself and the parent and
combines them using CombinedEnumeration.
Here is a patch that will fix that:
diff --git a/java/org/apache/catalina/loader/WebappClassLoaderBase.java
b/java/org/apache/catalina/loader/WebappClassLoaderBase.java
index aa747a5873..6f98f6e413 100644
--- a/java/org/apache/catalina/loader/WebappClassLoaderBase.java
+++ b/java/org/apache/catalina/loader/WebappClassLoaderBase.java
@@ -1121,7 +1121,9 @@ public abstract class WebappClassLoaderBase
extends URLClassLoader
// Enumerations are combined depends on how delegation is
configured
boolean delegateFirst = delegate || filter(name, false);
- if (delegateFirst) {
+ if(null == parentResources) {
+ return localResources;
+ } else if (delegateFirst) {
return new CombinedEnumeration(parentResources,
localResources);
} else {
return new CombinedEnumeration(localResources,
parentResources);
But my question is whether or not this is something that Tomcat should
be working-around. IMO the parent ClassLoader is buggy and should be
fixed, but it may be difficult or impossible to fix the parent, so it
may be worth it.
We could even log it including the class name of the offending ClassLoader.
WDYT?
-chris
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