Choose unique values for the 'webAppRootKey' context-param in your web.xml files!

本文详细解析了在Tomcat中同时运行多个项目时遇到的内存泄漏问题及webAppRootKey冲突原因。通过分析日志,定位到JDBC驱动未正确卸载和线程未停止导致的内存泄漏,以及由于多个项目配置相同的webAppRootKey导致的初始化错误。文章提供了修改web.xml中webAppRootKey参数的独特值以解决冲突的方法。

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报错日志

tomcat里面跑了多个项目,启动时报如下错误:

严重: The web application [/drc] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
十月 17, 2019 9:49:33 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/drc] appears to have started a thread named [Timer-10] but has failed to stop it. This is very likely to create a memory leak.
十月 17, 2019 9:49:33 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/drc] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0] but has failed to stop it. This is very likely to create a memory leak.
十月 17, 2019 9:49:33 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/drc] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1] but has failed to stop it. This is very likely to create a memory leak.
十月 17, 2019 9:49:33 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/drc] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2] but has failed to stop it. This is very likely to create a memory leak.
十月 17, 2019 9:49:33 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/drc] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak.

查看localhost.2019-10-17.log日志发现报错如下:

严重: Exception sending context initialized event to listener instance of class org.springframework.web.util.Log4jConfigListener
java.lang.IllegalStateException: Web app root system property already set to different value: 'webapp.root' = [/usr/local/apache-tomcat-7.0.55/webapps/mobile/] instead of [/usr/local/apache-tomcat-7.0.55/webapps/drc/] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
	at org.springframework.web.util.WebUtils.setWebAppRootSystemProperty(WebUtils.java:151)
	at org.springframework.web.util.Log4jWebConfigurer.initLogging(Log4jWebConfigurer.java:117)
	at org.springframework.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:45)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4992)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5490)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1247)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1898)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:473)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)

日志中字面表述:'webapp.root' = [/usr/local/apache-tomcat-7.0.55/webapps/mobile/] instead of [/usr/local/apache-tomcat-7.0.55/webapps/drc/] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
大概意思:webapp.root的这个key的值是 [/usr/local/apache-tomcat-7.0.55/webapps/mobile/],而不是[/usr/local/apache-tomcat-7.0.55/webapps/drc/] --为 'webAppRootKey' context-param 选择一个唯一值在你的web.xml中

解决方法

为后来加载的项目设置新的’webAppRootKey’值,修改项目的web.xml添加如下内容:

<context-param>
<param-name>webAppRootKey</param-name>
<param-value>drc.root</param-value>
</context-param>

在这里插入图片描述
重启tomcat,问题解决。

问题分析

可以理解为tomcat部署的多个项目都使用log4j,如果在项目的web.xml中没有定义webAppRootKey参数,那么她的缺省值就是"webapp.root",就我的这个问题而言,可以理解为“webapp.root”这个key已经指向了项目mobile,不能再指向项目drc了。
所以解决办法就是,在项目的web.xml里面声明 webAppRootKey。

参考链接

1.Choose unique values for the ‘webAppRootKey’ context-param in your web.xml files!
2.WebApproot in Spring

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name></display-name> <context-param> <param-name>contextConfigLocation</param-name> <param-value> classpath*:applicationContext*.xml classpath*:*Context.xml </param-value> </context-param> <context-param> <param-name>webAppRootKey</param-name> <param-value>rms.root</param-value> </context-param> <context-param> <param-name>log4jConfigLocation</param-name> <param-value>/WEB-INF/classes/log4j.properties</param-value> </context-param> <context-param> <param-name>log4jRefreshInterval</param-name> <param-value>60</param-value> </context-param> <listener> <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> </listener> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <listener> <listener-class>com.hg.filter.UrlAuthListen</listener-class> </listener> <listener> <listener-class>com.hg.filter.WebConfigListener</listener-class> </listener> <filter> <filter-name>openSessionInViewFilter</filter-name> <filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter </filter-class> <init-param> <param-name>singleSession</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>openSessionInViewFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <filter-name>XssFilter</filter-name> <filter-class>com.hg.aop.XssFilter</filter-class> </filter> <filter-mapping> <filter-name>XssFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- dwr 配置 --> <servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> <init-param> <param-name>activeReverseAjaxEnabled</param-name> <param-value>true</param-value> </init-param> <init-param> <param-name>crossDomainSessionSecurity</param-name> <param-value>false</param-value> </init-param> <init-param> <description>How quickly do scriptSessions timeout?</description> <param-name>scriptSessionTimeout</param-name> <param-value>1800000</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping> <listener> <listener-class>org.directwebremoting.servlet.EfficientShutdownServletContextAttributeListener</listener-class> </listener> <!-- dwr 配置 --> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>具体解释一下web.xml的配置
最新发布
07-08
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://JAVA.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name>springMVC</display-name> <welcome-file-list> <welcome-file>/WEB-INF/jsp/login.jsp</welcome-file> </welcome-file-list> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext-mybatis.xml</param-value> </context-param> <filter> <filter-name>encodingFilter</filter-name> <filter-class> org.springframework.web.filter.CharacterEncodingFilter </filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>spring</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springmvc-servlet.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>spring</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <context-param> <param-name>log4jConfigLocation</param-name> <param-value>classpath:log4j.properties</param-value> </context-param> <context-param> <param-name>webAppRootKey</param-name> <param-value>keshe_C12_09.root</param-value> </context-param> <listener> <listener-class> org.springframework.web.util.Log4jConfigListener </listener-class> </listener> </web-app>
07-16
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