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qos-ch / reload4j

reload4j is a drop-in replacement for log4j 1.2.17
Apache License 2.0
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ClassNotFoundException when using custom appenders in OSGi projects #72

Open simonzn opened 5 months ago

simonzn commented 5 months ago

Due to classpath separation in OSGi based projects, loading of custom Appenders fails with e.g.

log4j:ERROR Could not create an Appender. Reported error follows.
java.lang.ClassNotFoundException: ch.sbb.rcs.common.logging.LazyRollingFileAppender cannot be found by org.apache.log4j_1.2.25
    at org.eclipse.osgi.internal.loader.BundleLoader.generateException(BundleLoader.java:541)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:536)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:416)
    at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:168)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:375)
    at org.apache.log4j.helpers.Loader.loadClass(Loader.java:159)
    at org.apache.log4j.xml.DOMConfigurator.parseAppender(DOMConfigurator.java:240)
    at org.apache.log4j.xml.DOMConfigurator.findAppenderByName(DOMConfigurator.java:174)
    at org.apache.log4j.xml.DOMConfigurator.findAppenderByReference(DOMConfigurator.java:189)
    at org.apache.log4j.xml.DOMConfigurator.parseChildrenOfLoggerElement(DOMConfigurator.java:492)
    at org.apache.log4j.xml.DOMConfigurator.parseCategory(DOMConfigurator.java:415)
    at org.apache.log4j.xml.DOMConfigurator.parse(DOMConfigurator.java:932)
    at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:808)
    at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:721)
    at org.apache.log4j.xml.DOMConfigurator.configure(DOMConfigurator.java:839)
       [...]

The manifest should define a buddy policy to enable buddy class loading, as described in Context Class Loader Enhancements.

I'd suggest to add Eclipse-BuddyPolicy: registered. Then, the issue above is fixed by adding Eclipse-RegisterBuddy: org.apache.log4j to the bundle that provides the custom appender.