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https://issues.apache.org/jira/browse/LOGGING-192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17873595#comment-17873595
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Björn Kautler commented on LOGGING-192:
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It would not use JUL in my case, because the reason factory loading fails is
because commons-logging is not present on web.
So the legacy will also not work, because it is not present.
If commons-logging would be present on web it would use log4j, as the loading
would have worked.
Actually, thinking about it, maybe the procedure could be simplified to:
* is commons-logging found on web use web, otherwise use custom
* detect only on the one from step above
Again, given that the only reason it would fail after successful detection is,
that commons-logging is not present on web.
If factory loading could fail due to some other legit reason where the logic
should go on, it might be different.
But this check for whether commons-logging is present on the tccl would
probably also be much easier to add.
> NoClassDefFoundError: org/apache/logging/log4j/spi/LoggerAdapter when using
> custom classloader
> ----------------------------------------------------------------------------------------------
>
> Key: LOGGING-192
> URL: https://issues.apache.org/jira/browse/LOGGING-192
> Project: Commons Logging
> Issue Type: Bug
> Affects Versions: 1.3.0, 1.3.1, 1.3.2
> Environment: This behavior was observed while running Adopt Open JDK
> 11 and the latest version of Tomcat 9. The behavior can be reproduced
> outside of tomcat (see attached reproduction case).
> Reporter: Dave Dority
> Priority: Major
> Attachments: commons-logging-classloading-issue.zip
>
>
> If you have:
> * A web application running in Tomcat which contains commons-logging:1.2
> * That web application contains a custom classloader for loading a
> seperately distributed software component (whose dependencies will conflict
> with the dependencies of the web application).
> * The software component uses commons-logging:1.3.2
> When the web application attempts use software component, the code
> [here|https://github.com/apache/commons-logging/blob/rel/commons-logging-1.3.2/src/main/java/org/apache/commons/logging/LogFactory.java#L918-L938]
> looks for the presence of different logging implementation classes on the
> thread context classloader's (TCCL) classpath to select an optimal
> implementation. It seems like what is happening is that the LogFactory class
> looking for implementation class on the TCCL's classpath and the trying to
> load the selected factory from the web application's custom classloader (the
> loader for the instance of LogFactory that is running). This is the result:
> {code:java}
> Exception in thread "main" java.lang.NoClassDefFoundError:
> org/apache/logging/log4j/spi/LoggerAdapter
> at java.base/java.lang.Class.forName0(Native Method)
> at java.base/java.lang.Class.forName(Class.java:315)
> at
> org.apache.commons.logging.LogFactory.createFactory(LogFactory.java:419)
> at
> org.apache.commons.logging.LogFactory.lambda$newFactory$3(LogFactory.java:1431)
> at java.base/java.security.AccessController.doPrivileged(Native
> Method)
> at
> org.apache.commons.logging.LogFactory.newFactory(LogFactory.java:1431)
> at
> org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:928)
> at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:987)
> at
> org.component.ClassLoadedComponent.<clinit>(ClassLoadedComponent.java:7)
> at
> java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native
> Method)
> at
> java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
> at
> java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at
> java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
> at java.base/java.lang.Class.newInstance(Class.java:584){code}
> This occurs when the web application has commons-logging:1.2 and the software
> component has commons-logging:1.3.x. This does not occur when both are using
> version 1.2.
> Unfortunately, changing the web application's version of commons-logging is
> outside is not something I can influence.
> An isolated reproduction case is attached. It requires Java 11. To run it:
> * Unzip it to a directory.
> * Run
> {code:java}
> ./gradlew reproduceIssue{code}
>
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