将SpringMVC应用程序热部署到Tomcat7时出现OutOfMemoryError-可能与log4j2相关 [英] OutOfMemoryError when hot-deploying SpringMVC app to Tomcat7 - possible relation to log4j2
问题描述
我在热部署Spring-MVC 4.0(不是SpringBoot)Web应用程序时遇到麻烦.我正在尝试少使用xml，而仅使用JavaConfig.当我删除web.xml时，会出现OutOfMemoryErrors错误，或者当我部署一个只有空元素的空web.xml时，会出现 .并非每次热部署应用程序时都不会发生这种情况，并且在成功进行热部署之后，该应用程序仍可以正常运行，但是在使用此配置进行三到四次热部署后，会发生以下错误:
I am having trouble Hot Deploying a Spring-MVC 4.0 (not SpringBoot) Web Application. I am trying to go xml-less and just use JavaConfig. OutOfMemoryErrors result when I remove web.xml, or when I deploy an empty web.xml with nothing but an empty element. This does not happen every time the app is hot-deployed, and after a successful hot-deployment, the app does work correctly, but after three or four hot-deployments with this configuration the following error occurs:
Jul 03, 2015 10:49:43 AM org.springframework.web.context.ContextLoader initWebApplicationContext
SEVERE: Context initialization failed
java.lang.OutOfMemoryError: PermGen space
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:547)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:220)
at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:615)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:465)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5014)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5524)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1081)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1877)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Jul 03, 2015 10:49:44 AM org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor run
SEVERE: Unexpected death of background thread ContainerBackgroundProcessor[StandardEngine[Catalina]]
java.lang.OutOfMemoryError: PermGen space
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:188)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:816)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1655)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:328)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1374)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1546)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1556)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1524)
at java.lang.Thread.run(Thread.java:745)
Exception in thread "ContainerBackgroundProcessor[StandardEngine[Catalina]]" java.lang.OutOfMemoryError: PermGen space
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:188)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:816)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1655)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:328)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1374)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1546)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1556)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1524)
at java.lang.Thread.run(Thread.java:745)
显然，这种配置会导致内存泄漏.
Evidently memory is leaking with this configuration somehow.
此Web应用程序使用Log4j2可能相关，也可能无关. 更早的版本堆栈溢出问题对此进行了探讨.如果Web应用程序仅使用以下最小的web.xml
It may or may not be relevant that this web application uses Log4j2. An earlier Stack Overflow question explored this. If the web application uses just the following minimal web.xml
<?xml version="1.0"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<context-param>
<param-name>log4jConfiguration</param-name>
<param-value>file:///path/to/log4j2.xml</param-value>
</context-param>
</web-app>
然后可以反复部署WebApp，而不会出现这些错误.
then the WebApp can be hot-deployed over and over without getting these errors.
任何人都可以猜测这里可能发生的事情吗?
Can anyone hazard a guess at what could be going on here?
更新:-参见下面@Makoton和我本人之间的讨论.似乎很可能存在与从应用程序(Java Config方式)加载log4j2与从web.xml(传统方式)加载log4j2有关的垃圾收集问题.请参阅这篇文章，该文章揭露了针对该问题的经典"堆栈溢出建议(类似于由Makoton引用).
Update: - See the discussion between @Makoton and myself below. It appears that there may well be a Garbage collection issue relating to loading log4j2 from the application (the Java Config way) vs loading it from web.xml (the traditional way). See this article which debunks the "classic" Stack Overflow suggestion for this problem (similar to that cited by Makoton).
这让我想到了SpringBoot，据我所知，它将Tomcat作为应用程序的一部分进行加载.这可能是解决此问题的一种方法.
This makes me think about SpringBoot, which, as I understand it, loads Tomcat as part of the application. This might be one solution to this problem.
推荐答案
I believe Luke is right that this issue may be caused by a bug in Log4j2.
错误在于，如果web.xml中没有<display-name>元素，则负责log4j资源管理的Log4jServletContextListener类只能启动，而不能停止log4j.
The bug is that if the <display-name> element is not present in the web.xml, the Log4jServletContextListener class responsible for log4j resource management can only start, but not stop log4j.
这意味着在停止或重新启动Web应用程序时不会进行清理. JMX MBean未注销，但所有线程也未停止，因此Log4j类未卸载.每次重新启动Web应用程序时，泄漏的内存都会增加，因为每个Web应用程序都有自己的类加载器(因此VM将它们视为不同的类).
This means that no cleanup happens when the web application is stopped or restarted. JMX MBeans are not unregistered, but also any threads are not stopped, and as a result Log4j classes are not unloaded. The leaked memory grows every time the web app is restarted, because each web app has its own classloader (so the VM sees them as different classes).
此错误现已在Git master中修复，该修复程序将成为log4j 2.5发行版的一部分.同时，请在您的web.xml中使用<display-name>元素.
This bug is fixed in Git master now and the fix will be part of the log4j 2.5 release. Meanwhile, please use a <display-name> element in your web.xml.
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