JVM命令jinfo

      jinfo也是jvm中参与的一个命令，可以查看运行中jvm的全部参数，还可以设置部分参数。

 

格式

     jinfo [ option ] pid

     jinfo [ option ] executable core

     jinfo [ option ] [server-id@]remote-hostname-or-IP

 

    

参数说明

     pid  对应jvm的进程id

     executable core 产生core dump文件

     [server-id@]remote-hostname-or-IP  远程的ip或者hostname，server-id标记服务的唯一性id

 

option

     no option   输出全部的参数和系统属性

     -flag  name  输出对应名称的参数

     -flag [+|-]name  开启或者关闭对应名称的参数

     -flag name=value  设定对应名称的参数

     -flags  输出全部的参数

     -sysprops  输出系统属性

 

实例

     1 输出全部的参数和系统属性

[java@xftest0 ~]$ jinfo 43934
Attaching to process ID 43934, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.45-b01
Java System Properties:

java.runtime.name = Java(TM) SE Runtime Environment
sun.boot.library.path = /usr/java/jdk1.6.0_45/jre/lib/amd64
java.vm.version = 20.45-b01
java.vm.vendor = Sun Microsystems Inc.
java.vendor.url = http://java.sun.com/
path.separator = :
java.vm.name = Java HotSpot(TM) 64-Bit Server VM
file.encoding.pkg = sun.io
sun.java.launcher = SUN_STANDARD
env = dev
user.country = US
sun.os.patch.level = unknown

 

2 只输出参数

[java@xftest0 ~]$ jinfo -flags 43934
Attaching to process ID 43934, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.45-b01

-Djava.awt.headless=true -Djava.net.preferIPv4Stack=true

 

刚才提到不是全部参数可以修改，只有部分，下面是可以修改的参数列表

SZ-sten:go sten$ java -XX:+PrintFlagsFinal -version |grep manageable
     intx CMSAbortablePrecleanWaitMillis            = 100             {manageable}
     intx CMSWaitDuration                           = 2000            {manageable}
     bool HeapDumpAfterFullGC                       = false           {manageable}
     bool HeapDumpBeforeFullGC                      = false           {manageable}
     bool HeapDumpOnOutOfMemoryError                = false           {manageable}
    ccstr HeapDumpPath                              =                 {manageable}
    uintx MaxHeapFreeRatio                          = 100             {manageable}
    uintx MinHeapFreeRatio                          = 0               {manageable}
     bool PrintClassHistogram                       = false           {manageable}
     bool PrintClassHistogramAfterFullGC            = false           {manageable}
     bool PrintClassHistogramBeforeFullGC           = false           {manageable}
     bool PrintConcurrentLocks                      = false           {manageable}
     bool PrintGC                                   = false           {manageable}
     bool PrintGCDateStamps                         = false           {manageable}
     bool PrintGCDetails                            = false           {manageable}
     bool PrintGCTimeStamps                         = false           {manageable}  

 

命令  java -XX:+PrintFlagsFinal -version是输出全部的参数