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https://issues.apache.org/jira/browse/LOG4J2-1971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16084371#comment-16084371
]
Gary Gregory commented on LOG4J2-1971:
--------------------------------------
The class {{org.apache.logging.log4j.core.impl.Log4jProvider}} has been around
for a while, it is not new in 2.9-SNAPSHOTs.
This error seems to say that
{{org.apache.logging.log4j.core.impl.Log4jProvider}} is not a subtype of
{{org.apache.logging.log4j.spi.Provider}}, which it is in our code:
{code:java}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.impl;
import org.apache.logging.log4j.spi.Provider;
/**
* Binding for the Log4j API.
*/
public class Log4jProvider extends Provider {
public Log4jProvider() {
super(10, "2.6.0", Log4jContextFactory.class);
}
}
{code}
This smells like something is not as we expect with class loaders in OSGi, but
what?
> ClassCastException: org.eclipse.osgi.internal.loader.SystemBundleLoader$1
> cannot be cast to java.lang.ClassLoader
> -----------------------------------------------------------------------------------------------------------------
>
> Key: LOG4J2-1971
> URL: https://issues.apache.org/jira/browse/LOG4J2-1971
> Project: Log4j 2
> Issue Type: Bug
> Affects Versions: 2.8
> Reporter: liwenxian2017
> Fix For: 2.9
>
>
> When I migrated log4j from log4j 1.2.17 to log4j 2.8, There is an Exception
> like this:
> java.lang.ClassCastException:
> org.eclipse.osgi.internal.loader.SystemBundleLoader$1 cannot be cast to
> java.lang.ClassLoaderat
> org.eclipse.osgi.internal.resolver.BundleDescriptionImpl$DescriptionWiring.getClassLoader(BundleDescriptionImpl.java:1229)
> ~[org.eclipse.osgi.jar:?]at
> org.apache.logging.log4j.core.osgi.Activator.scanBundleForPlugins(Activator.java:70)
> ~[log4j-core.jar:2.8]at
> org.apache.logging.log4j.core.osgi.Activator.bundleChanged(Activator.java:91)
> ~[log4j-core.jar:2.8]at
> org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:847)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.Framework.publishBundleEventPrivileged(Framework.java:1568)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1504)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1499)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:247)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:438)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:1)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
> ~[org.eclipse.osgi.jar:?]at
> org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:340)
> ~[org.eclipse.osgi.jar:?]
> I checked Activator.java in log4j-core:
> ...
> 86 @Override
> 87 public void bundleChanged(final BundleEvent event) {
> 88 switch (event.getType()) {
> 89 // FIXME: STARTING instead of STARTED?
> 90 case BundleEvent.STARTED:
> 91 scanBundleForPlugins(event.getBundle());
> 92 break;
> in line 91, it called scanBundleForPlugins for every bundles. But in line
> 60-61, it does not scan system bundle for plugins
> 57 private static void scanInstalledBundlesForPlugins(final BundleContext
> context) {
> 58 final Bundle[] bundles = context.getBundles();
> 59 for (final Bundle bundle : bundles) {
> 60 // LOG4J2-920: don't scan system bundle for plugins
> 61 if (bundle.getState() == Bundle.ACTIVE && bundle.getBundleId() != 0)
> {
> 62 // TODO: bundle state can change during this
> 63 scanBundleForPlugins(bundle);
> And org.eclipse.osgi_3.8.1 's bundle ID is just 0. So it skipped bundle
> org.eclipse.osgi in line 61-63. but it does not in line 91
> If I changed line 91 to:
> if (event.getBundle().getState() == Bundle.ACTIVE &&
> event.getBundle().getBundleId() != 0) {
> scanBundleForPlugins(event.getBundle());
> }
> The exception goes away.
> So is this a bug? Or this is NOT a bug and there is a workaround for this
> Exception? Thanks.
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