jboss的jvm缓存和heap内存

PermGen space的全称是Permanent Generation space,是指内存的永久保存区域OutOfMemoryError: PermGen space从表面上看就是内存益出，解决方法也一定是加大内存。说说为什么会内存益出：这一部分用于存放Class和Meta的信息,Class在被 Load的时候被放入PermGen space区域，它和和存放Instance的Heap区域不同,GC(Garbage Collection)不会在主程序运行期对PermGen space进行清理，所以如果你的APP会LOAD很多CLASS的话,就很可能出现PermGen space错误。这种错误常见在web服务器对JSP进行pre compile的时候。

改正方法，在 run.bat 中加入：-Xms256m -Xmx512m -XX:MaxNewSize=256m -XX:MaxPermSize=256m

因为项目中引用了很多的 jar 包，而这些 jar 包中的 class 信息会被 JBoss 的 class loader 加载到 PermGen space 区域，在 JVM 默认的情况下，该部分空间的大小只有 4M，在 jar 包非常多的情况下，显然是不够用的，所以通过 -XX:MaxPermSize=256m 指定最大值后即可解决问题。

   另外，如果 heap 内存不足出现 java.lang.OutOfMemoryError: Java heap space 时，可以通过 -Xmx512m 指定最大 heap 内存来解决这样的问题。

   run.bat样例如下：

@echo off
rem -------------------------------------------------------------------------
rem JBoss Bootstrap Script for Win32
rem -------------------------------------------------------------------------

rem $Id: run.bat 73584 2008-05-22 12:09:26Z [e-mail] $

@if not "%ECHO%" == ""   echo %ECHO%
@if "%OS%" == "Windows_NT"   setlocal

set DIRNAME=.\
if "%OS%" == "Windows_NT" set DIRNAME=%~dp0%
set PROGNAME=run.bat
if "%OS%" == "Windows_NT" set PROGNAME=%~nx0%

pushd %DIRNAME%..
set JBOSS_HOME=%CD%
popd

REM Add bin/native to the PATH if present
if exist "%JBOSS_HOME%\bin\native" set PATH=%JBOSS_HOME%\bin\native;%PATH%
if exist "%JBOSS_HOME%\bin\native" set JAVA_OPTS=%JAVA_OPTS% -Djava.library.path="%PATH%"

rem Find run.jar, or we can't continue

set RUNJAR=%JBOSS_HOME%\bin\run.jar
if exist "%RUNJAR%" goto FOUND_RUN_JAR
echo Could not locate %RUNJAR%. Please check that you are in the
echo bin directory when running this script.
goto END

:FOUND_RUN_JAR

if not "%JAVA_HOME%" == "" goto ADD_TOOLS

set JAVA=java

echo JAVA_HOME is not set.   Unexpected results may occur.
echo Set JAVA_HOME to the directory of your local JDK to avoid this message.
goto SKIP_TOOLS

:ADD_TOOLS

set JAVA=%JAVA_HOME%\bin\java

rem A full JDK with toos.jar is not required anymore since jboss web packages
rem the eclipse jdt compiler and javassist has its own internal compiler.
if not exist "%JAVA_HOME%\lib\tools.jar" goto SKIP_TOOLS

rem If exists, point to the JDK javac compiler in case the user wants to
rem later override the eclipse jdt compiler for compiling JSP pages.
set JAVAC_JAR=%JAVA_HOME%\lib\tools.jar

:SKIP_TOOLS

rem If JBOSS_CLASSPATH or JAVAC_JAR is empty, don't include it, as this will
rem result in including the local directory in the classpath, which makes
rem error tracking harder.
if not "%JAVAC_JAR%" == "" set RUNJAR=%JAVAC_JAR%;%RUNJAR%
if "%JBOSS_CLASSPATH%" == "" set RUN_CLASSPATH=%RUNJAR%
if "%RUN_CLASSPATH%" == "" set RUN_CLASSPATH=%JBOSS_CLASSPATH%;%RUNJAR%

set JBOSS_CLASSPATH=%RUN_CLASSPATH%

rem Setup JBoss specific properties
set JAVA_OPTS=%JAVA_OPTS% -Dprogram.name=%PROGNAME%

rem Add -server to the JVM options, if supported
"%JAVA%" -server -version 2>&1 | findstr /I hotspot > nul
if not errorlevel == 1 (set JAVA_OPTS=%JAVA_OPTS% -server)

rem JVM memory allocation pool parameters. Modify as appropriate.
set JAVA_OPTS=%JAVA_OPTS% -Xms256m -Xmx512m -XX:MaxNewSize=256m -XX:MaxPermSize=256m

rem With Sun JVMs reduce the RMI GCs to once per hour
set JAVA_OPTS=%JAVA_OPTS% -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000

rem JPDA options. Uncomment and modify as appropriate to enable remote debugging.
rem set JAVA_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=y %JAVA_OPTS%

rem Setup the java endorsed dirs
set JBOSS_ENDORSED_DIRS=%JBOSS_HOME%\lib\endorsed

echo ===============================================================================
echo.
echo   JBoss Bootstrap Environment
echo.
echo    JBOSS_HOME: %JBOSS_HOME%
echo.
echo    JAVA: %JAVA%
echo.
echo   JAVA_OPTS: %JAVA_OPTS%
echo.
echo    CLASSPATH: %JBOSS_CLASSPATH%
echo.
echo ===============================================================================
echo.

:RESTART
"%JAVA%" %JAVA_OPTS% ^
    -Djava.endorsed.dirs="%JBOSS_ENDORSED_DIRS%" ^
    -classpath "%JBOSS_CLASSPATH%" ^
    org.jboss.Main %*

if ERRORLEVEL 10 goto RESTART

:END
if "%NOPAUSE%" == "" pause

:END_NO_PAUSE