jvm参数设置

#============================ Memory Parameter ===============
MEM_ARGS="-Xms1024m -Xmx1024m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:NewRatio=4 -XX:SurvivorRatio=6  -Xverbosegc:file=gc.`date + %Y%m%d_%H%M%S`.log"


-XX:+HeapDumpOnOutOfMemoryError
AIX:
MEM_ARGS="-Xms1024m -Xmx1536m  -verbose:gc -Xverbosegclog:gc.log"

Linux:
-Xms1800M -Xmx1800M -Xmn600M -Xss512K -XX:PermSize=300M -XX:MaxPermSize=300M -XX:SurvivorRatio=5000 -XX:MaxTenuringThreshold=0  -Xnoclassgc -XX:+DisableExplicitGC -XX:+UseParNewGC  -XX:+PrintClassHistogram -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -Xloggc:/usr/local/apache/htdocs/SoapMmsService/logs/gc.log  




linux下查看虚拟机的状态

命令： ps auxwww 找到java的进程

然后进入java的bin目录 调用jmap -heap PID 进行查看内存，cpu的情况

或者调用 ./jstat -gcutil PID 500（刷新频率） 100（次数）查看jvm的gc情况和内存使用情况

jstat命令的参数及查看情况可以查询jdk的doc，里面有说明

 

jvm的gc机制是分代gc：顺序是 Eden -->from/to--->tenured(old)

gc分大gc和小gc