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谈JAVA_OPTS环境变量不起作用


最*在处理运行一个java应用时,老是出现java.lang.OutOfMemoryError: Java heap space.即时我在环境变量里设置了JAVA_OPTS -Xmx2048m还是报错。?



javaeye上搜索了一番,发现很多人都有这个疑问。经过Team Leader的指导,发现:?



1、JAVA_OPTS只对tomcat/weblogic等Web服务器中间件有效,以“java -cp [*.jar] test.Main”方式运行的不会去读取JAVA_OPTS.?



2、如果在运行java类,需要设置Heap Size的话,需要如下方式:?

java -Xmx2048m -jar test.jar?

或者java -Xmx1024m -cp douglas.jar com.douglas.Main?

3、如果是在Unix或者Aix服务器上,可以直接写下如下语句?

export JAVA_OPTS=-Xmx1024m -Djava.awt.headless=true?

java $JAVA_OPTS -cp douglas.jar com.douglas.Main?

或者vi test.sh文件,写下:?

#!/bin/sh?

classpath=./douglas.jar?

/usr/java5/bin/java -Xmx1024M -cp $classpath com.douglas.Main?

4、对于非Java语言(C++)调用Java代码,最好的方式是提供给操作员设置的页面,在申明JavaVM时,将JavaOPTS数值放置至JavaVM中。?



对于JVM设置,可以查考如下配置example:?


# Memory configuration
JAVA_OPTS="-server"
JAVA_OPTS="$JAVA_OPTS -Xms1280m"
JAVA_OPTS="$JAVA_OPTS -Xmx1280m"
JAVA_OPTS="$JAVA_OPTS -XX:NewSize=640m"
JAVA_OPTS="$JAVA_OPTS -XX:MaxNewSize=640m"
JAVA_OPTS="$JAVA_OPTS -XX:SurvivorRatio=5"
JAVA_OPTS="$JAVA_OPTS -XX:TargetSurvivorRatio=90"
JAVA_OPTS="$JAVA_OPTS -XX:MaxTenuringThreshold=12"
JAVA_OPTS="$JAVA_OPTS -XX:+UseConcMarkSweepGC"
JAVA_OPTS="$JAVA_OPTS -XX:+CMSIncrementalMode"
JAVA_OPTS="$JAVA_OPTS -XX:+CMSIncrementalPacing"
JAVA_OPTS="$JAVA_OPTS -XX:+CMSParallelRemarkEnabled"
JAVA_OPTS="$JAVA_OPTS -XX:+UseParNewGC"
JAVA_OPTS="$JAVA_OPTS -XX:PermSize=64m"
JAVA_OPTS="$JAVA_OPTS -XX:MaxPermSize=64m"
JAVA_OPTS="$JAVA_OPTS -XX:+UseTLAB"

# Enable class unloading (needed with ConcMarkSweepGC
JAVA_OPTS="$JAVA_OPTS -XX:+CMSClassUnloadingEnabled"
JAVA_OPTS="$JAVA_OPTS -XX:+CMSPermGenSweepingEnabled"

# debug and memory tweaks to avoid Hotspot Compiler Failure
JAVA_OPTS="$JAVA_OPTS -XX:+PrintCompilation"
JAVA_OPTS="$JAVA_OPTS -XX:CodeCacheMinimumFreeSpace=2M"
JAVA_OPTS="$JAVA_OPTS -XX:ReservedCodeCacheSize=64M"
JAVA_OPTS="$JAVA_OPTS -XX:CompileCommandFile=/my/portal/bin/hotspot_compiler"

# Enable JMX Remote Monitoring
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.port=9000"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.password.file=/my/portal/bin/jmxremote.password"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.access.file=/my/portal/bin/jmxremote.access"

# turn on some debug for GC only print the distribution when doing tuning
JAVA_OPTS="$JAVA_OPTS -verbose:gc"
JAVA_OPTS="$JAVA_OPTS -XX:+PrintGCTimeStamps"
JAVA_OPTS="$JAVA_OPTS -XX:+PrintGCDetails"
#JAVA_OPTS="$JAVA_OPTS -XX:+PrintTenuringDistribution"
JAVA_OPTS="$JAVA_OPTS -Xloggc:/my/portal/logs/portal/gc.log"

# Enable remote debugging port
JAVA_OPTS="$JAVA_OPTS -Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n"







原文章地址:http://hi.baidu.com/goglad/item/39f0529dca365ddb7a7f01ca





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