PermGen space错误解决方法
在看下文之前，首先要确认意见事情，就是你是怎样启动tomcat的，我们在平时的开发环境其中，都是通过startup.bat方式启动tomcat的，那么你依照以下的方式，去改动/bin/catalina.bat是没有问题的。可是假设你是生产环境下，我们一般都希望使用windows服务方式去启动tomcat，此时之前改动的配置文件是没实用的。由于windows服务启动tomcat不再去载入catalina.bat其中的參数了，而是去载入注冊表中的參数，所以我们须要改动注冊表。
HKEY_LOCAL_MACHINE/SOFTWARE/Apache Software Foundation/Procrun 2.0/Tomcat_APPNAME/Parameters/Java，改动JvmMs和JvmMx的值，当前我都将其设定为1024，也就是1个G的容量。详细性能再后面继续观察。 之前还真不知道windows服务启动和startup.bat启动的差别。 windowsserver启动是在注冊表中载入參数，startup.bat启动是在catalina.bat载入參数。
1.參考：
http://blog.csdn.net/fox009/article/details/5633007
http://hi.baidu.com/like_dark/blog/item/19c1948b3292b0799f2fb468.html
http://anyeeye.iteye.com/blog/444624
Tomcat6性能调优
出现java.lang.OutOfMemoryError: PermGen space
http://www.mkyong.com/tomcat/tomcat-javalangoutofmemoryerror-permgen-space/
2.报错：
Exception in thread "DispatcherThread" java.lang.OutOfMemoryError: PermGen space Exception in thread "ContainerBackgroundProcessor[StandardEngine[Catalina]]" java.lang.OutOfMemoryError: PermGen space Exception in thread "State Saver" java.lang.OutOfMemoryError: PermGen space Exception in thread "AWT-Windows" java.lang.OutOfMemoryError: OutOfMemoryError
3.原因：
PermGen space的全称是Permanent Generation space,是指内存的永久保存区域,这块内存主要是被JVM存放Class和Meta信息的,Class在被Loader时就会被放到PermGen space中,它和存放类实例(Instance)的Heap区域不同,GC(Garbage Collection)不会在主程序执行期对PermGen space进行清理，所以假设你的应用中有非常多CLASS的话,就非常可能出现PermGen space错误,这样的错误常见在webserver对JSP进行pre
compile的时候。假设你的WEB APP下都用了大量的第三方jar, 其大小超过了jvm默认的大小(4M)那么就会产生此错误信息了。
4.解决方法1：
手动设置MaxPermSize大小，假设是linux系统，改动TOMCAT_HOME/bin/catalina.sh，假设是windows系统，改动TOMCAT_HOME/bin/catalina.bat，
在“echo "Using CATALINA_BASE: $CATALINA_BASE"”上面添�下面行：
JAVA_OPTS="-server -XX:PermSize=64M -XX:MaxPermSize=128m
建议：将同样的第三方jar文件移置到tomcat/shared/lib文件夹下，这样能够达到降低jar 文档反复占用内存的目的。
5.解决方法2
改动eclipse.ini文件，改动例如以下：
-vmargs -Dosgi.requiredJavaVersion=1.5 -Xms128m -Xmx512m -XX:PermSize=64M -XX:MaxPermSize=128M
假设还报错，能够考虑例如以下改动
-vmargs -Dosgi.requiredJavaVersion=1.5 -Xms512m -Xmx1024m -XX:PermSize=256M -XX:MaxPermSize=512M
报错：
2011-11-21 21:10:46 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc 严重: The web application [/Application] 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. 2011-11-21 21:10:46 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads 严重: The web application [/Application] appears to have started a thread named [MySQL Statement Cancellation Timer] but has failed to stop it. This is very likely to create a memory leak. 2011-11-21 21:10:46 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads 严重: The web application [/Application] appears to have started a thread named [AWT-Windows] but has failed to stop it. This is very likely to create a memory leak. 2011-11-21 21:10:46 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads 严重: The web application [/Application] appears to have started a thread named [Thread-14] but has failed to stop it. This is very likely to create a memory leak. 2011-11-21 21:10:46 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap 严重: The web application [/Application] created a ThreadLocal with key of type [net.sf.json.AbstractJSON$1] (value [net.sf.json.AbstractJSON$1@3661eeb]) and a value of type [java.util.HashSet] (value [[]]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. 2011-11-21 21:10:50 org.apache.catalina.core.ApplicationContext log 信息: Initializing Spring FrameworkServlet 'Dispatcher'
改动catalina.bat
加入�
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms1536m -Xmx1536m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+DisableExplicitGC"
例子
# JSSE_HOME (Optional) May point at your Java Secure Sockets Extension # (JSSE) installation, whose JAR files will be added to the # system class path used to start Tomcat. # # CATALINA_PID (Optional) Path of the file which should contains the pid # of catalina startup java process, when start (fork) is used # # $Id: catalina.sh 609438 2008-01-06 22:14:28Z markt $ # ----------------------------------------------------------------------------- JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms1536m -Xmx1536m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+DisableExplicitGC" # OS specific support. $var _must_ be set to either true or false. cygwin=false os400=false darwin=false case "`uname`" in CYGWIN*) cygwin=true;; OS400*) os400=true;; Darwin*) darwin=true;; esac # resolve links - $0 may be a softlink PRG="$0"
详细參数依据自己机器情况而定
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m
-Xmx512m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m
-XX:MaxPermSize=256m -XX:+DisableExplicitGC"
