如何清除tomcat中的PermGen空间错误 [英] How to clear PermGen space Error in tomcat

问题描述

我在Windows环境中工作，每次与tomcat一起工作时都会出现此错误-

I am working in a Windows Environment, and I am getting this error every time I am working with tomcat-

Apr 30, 2012 5:30:37 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet default threw exception
java.lang.OutOfMemoryError: PermGen space
2012-04-30 17:30:37.719 INFO net.spy.memcached.MemcachedConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@4ae53a99
2012-04-30 17:30:37.719 INFO net.spy.memcached.MemcachedConnection:  Reconnecting due to failure to connect to {QA sa=localhost/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0}
java.net.ConnectException: Connection refused: no further information
Apr 30, 2012 5:30:37 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet default threw exception
java.lang.OutOfMemoryError: PermGen space
Exception in thread "Memcached IO over {MemcachedConnection to localhost/127.0.0.1:11211}" java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:38 PM org.apache.coyote.http11.Http11Processor process
SEVERE: Error processing request
java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:38 PM org.apache.coyote.http11.Http11Processor process
SEVERE: Error processing request
java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:38 PM org.apache.coyote.http11.Http11Processor process
SEVERE: Error processing request
java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:41 PM org.apache.catalina.connector.CoyoteAdapter service
SEVERE: An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:43 PM org.apache.catalina.core.StandardHostValve custom
SEVERE: Exception Processing ErrorPage[exceptionType=java.lang.Throwable, location=/error.action]
java.lang.OutOfMemoryError: PermGen space
Apr 30, 2012 5:30:42 PM org.apache.catalina.core.StandardHostValve custom
SEVERE: Exception Processing ErrorPage[exceptionType=java.lang.Throwable, location=/error.action]
java.lang.OutOfMemoryError: PermGen space
Exception in thread "ContainerBackgroundProcessor[StandardEngine[Catalina]]" java.lang.OutOfMemoryError: PermGen space

我尝试在系统变量中添加JAVA_OPTS with the value as -Xms1024m -Xmx1024m，但是仍然一次又一次遇到相同的错误(java.lang.OutOfMemoryError:PermGen space).

I tried adding JAVA_OPTS with the value as -Xms1024m -Xmx1024m in System Variables, but I am stillgetting the same error (java.lang.OutOfMemoryError: PermGen space) again and again.

任何帮助将不胜感激.我也阅读了有关Stack Overflow的其他文章，但没有解决.

Any help will be appreciated. I have also read other posts on Stack Overflow also but it didn't work out.

推荐答案

PermGen空间是Tomcat用于存储类定义(仅定义，没有实例化)和已嵌入的字符串池的区域.根据经验，PermGen空间问题往往在开发环境中经常发生，这是因为Tomcat每次部署WAR或执行jspc时(当您编辑jsp文件时)都必须加载新类.就个人而言，在进行开发测试时，我倾向于部署和重新部署大量战争，所以我知道我早晚会耗尽(主要是因为Java的GC周期仍然很糟糕，因此，如果您快速且频繁地重新部署战争，足够，空间填满的速度超出了他们的管理能力.

The PermGen space is what Tomcat uses to store class definitions (definitions only, no instantiations) and string pools that have been interned. From experience, the PermGen space issues tend to happen frequently in dev environments really since Tomcat has to load new classes every time it deploys a WAR or does a jspc (when you edit a jsp file). Personally, I tend to deploy and redeploy wars a lot when I’m in dev testing so I know I’m bound to run out sooner or later (primarily because Java’s GC cycles are still kinda crap so if you redeploy your wars quickly and frequently enough, the space fills up faster than they can manage).

从理论上讲，这在生产环境中应该不是问题，因为(希望)您不会在10分钟内更改代码库.如果仍然发生，那意味着您的代码库(和相应的库依赖项)对于默认的内存分配来说太大了，您只需要弄乱堆栈和堆的分配.我认为这些标准类似于:

This should theoretically be less of an issue in production environments since you (hopefully) don’t change the codebase on a 10 minute basis. If it still occurs, that just means your codebase (and corresponding library dependencies) are too large for the default memory allocation and you’ll just need to mess around with stack and heap allocation. I think the standards are stuff like:

-XX:MaxPermSize=SIZE

不过，我发现永久解决此问题的最佳方法是允许卸载类，以使您的PermGen永远不会用完:

I’ve found however the best way to take care of that for good is to allow classes to be unloaded so your PermGen never runs out:

-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled

类似的东西在过去对我来说是神奇的.一件事，在使用这些性能时，需要进行重大的性能折衷，因为对于每个请求或类似的请求，permgen扫描将产生额外的2个请求.您需要在权衡利弊之间取得平衡.

Stuff like that worked magic for me in the past. One thing tho, there’s a significant performance tradeoff in using those, since permgen sweeps will make like an extra 2 requests for every request you make or something along those lines. You’ll need to balance your use with the tradeoffs.

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