使用log4j升级到Tomcat9后的LinkageError

问题描述

我们最近将应用程序从Tomcat 7更新到了Tomcat9。与此同时，我们还将使用的JRE从jre 6更新到了OpenJDK 11。现在到目前为止一切正常。该应用程序启动了一切，除了日志记录正在运行之外。似乎与tomcat记录器和我们的log4j记录器存在冲突。我们得到：

SCHWERWIEGEND [main] org.apache.catalina.core.StandardContext.loadOnStartup Servlet [StartupServlet] in web application [/Application] threw load() exception
java.lang.LinkageError: loader constraint violation: when resolving field "log" of type org.apache.log4j.Logger,the class loader org.apache.catalina.loader.ParallelWebappClassLoader @e48059 of the current class,StartupServlet,and the class loader 'app' for the field's defining type,org.fp.Main,have different Class objects for type org.apache.log4j.Logger (StartupServlet is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @e48059,parent loader java.net.urlclassloader @18f65a4; org.fp.Main is in unnamed module of loader 'app')
    at StartupServlet.init(StartupServlet.java:41)
    at javax.servlet.GenericServlet.init(GenericServlet.java:158)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1134)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1089)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:983)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4864)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1133)
    at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1866)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(UnkNown Source)
    at java.base/java.util.concurrent.FutureTask.run(UnkNown Source)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(UnkNown Source)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1045)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:429)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1576)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:309)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
    at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:423)
    at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:366)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:936)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase$startChild.call(ContainerBase.java:1384)
    at org.apache.catalina.core.ContainerBase$startChild.call(ContainerBase.java:1374)
    at java.base/java.util.concurrent.FutureTask.run(UnkNown Source)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(UnkNown Source)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(UnkNown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(UnkNown Source)
    at java.base/java.lang.reflect.Method.invoke(UnkNown Source)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:343)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:474)

现在，我们仍然使用log4j 1.2.8版，并且有一个属性文件，其中设置了所有内容（模式等）。现在，我们通过使用该属性文件来更改日志路径：

Properties p = new Properties();
p.load(new FileInputStream(Main.Application+File.separator+"log4j.properties"));           
p.setProperty("log4j.appender.fileout.File",logPath+File.separator+PRODUKT+".log");
PropertyConfigurator.configure(p);

此方法以前曾起作用，但现在看来这样做会使记录器崩溃。现在这不会使应用程序崩溃。一切正常，我们只是没有任何日志。

如果我们使用

BasicConfigurator.configure()

它似乎有效。该日志不在我们的日志文件中，但是tomcat日志有一个输出，看起来不错。有人对此有想法吗？根据我对LinkageErrors的了解，在更改类（通过编译）并且旧类现在不兼容之后，就会出现问题。因此，这意味着我们将在我们的类路径中设置两个log4j-Jars。但是类路径看起来还不错。我发现tomcat配置了一个日志管理器。

-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djava.util.logging.config.file=C:/Program Files/Application/tomcat/conf/logging.properties

这可能是原因吗？与往常一样，感谢您的帮助！

解决方法

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java java log4j tomcat9