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  • jinfo用法说明

    以下几种用法

    -flags pid :打印当前VM的参数

    -flag <name> pid:打印指定JVM的参数值 

    -flag [+|-]<name> pid:设置指定JVM参数的布尔值

    -flag <name>=<value> pid:设置指定JVM参数的值

    -sysprops  pid : 获取当前系统参数包括-D设置的参数

     当然并不是所有的参数都是允许修改的,只允许修改其中部分参数。

    可以通过PrintFlagFinal参数打印支持的参数。

    java -XX:+PrintFlagsFinal -version|grep manageable  
    
    输出结果:
         intx CMSAbortablePrecleanWaitMillis            = 100                                 {manageable}
         intx CMSTriggerInterval                        = -1                                  {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 PrintGCID                                 = false                               {manageable}
         bool PrintGCTimeStamps                         = false                               {manageable}
    java version "1.8.0_51"
    Java(TM) SE Runtime Environment (build 1.8.0_51-b16)
    Java HotSpot(TM) 64-Bit Server VM (build 25.51-b03, mixed mode)

    1、jinfo -flags pid  

    ./jinfo -flags 13553
    

      输出结果:

    Attaching to process ID 13553, please wait...
    Debugger attached successfully.
    Server compiler detected.
    JVM version is 25.51-b03
    Non-default VM flags: -XX:CICompilerCount=4 -XX:InitialHeapSize=526385152 -XX:MaxHeapSize=8415870976 -XX:MaxNewSize=2804940800 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=175112192 -XX:OldSize=351272960 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseFastUnorderedTimeStamps -XX:+UseParallelGC 
    Command line: 

    2、jinfo -flag <name> pid

    ./jinfo -flag InitialHeapSize 13553
    

      输出结果:

    -XX:InitialHeapSize=526385152
    

    3、jinfo -flag [+|-]<name> pid

    ./jinfo -flag +PrintGCDetails 13553
    
    ./jinfo -flag -PrintGCDetails 13553
    

    4、jinfo -flag <name>=<value> pid

    ./jinfo -flag MaxHeapFreeRatio=10 13553
    

    5、jinfo -sysprops  pid

    通过以下方式启动Java程序:java -Dtest.dir=/opt -cp test.jar test.Main

    ./jinfo -flag test.dir 3532

    输出结果中,存在启动时添加的-Dtest.dir=/opt

    test.dir = /opt
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  • 原文地址:https://www.cnblogs.com/woniu4/p/8178833.html
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