如何查看jvm中的各种参数以及默认值_wisgood的专栏

CSDN博客_如何查看jvm参数 · · 21 次点击 · · 开始浏览    

1 标准参数

标准参数(-),所有的JVM实现都必须实现这些参数的功能,而且向后兼容;
通过命令 java即可查看
如下

where options include:
    -d32          use a 32-bit data model if available
    -d64          use a 64-bit data model if available
    -server       to select the "server" VM
                  The default VM is server,
                  because you are running on a server-class machine.


    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A : separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D<name>=<value>
                  set a system property
    -verbose:[class|gc|jni]
                  enable verbose output
    -version      print product version and exit

2 非标准参数(-X)

非标准参数(-X),默认jvm实现这些参数的功能,但是并不保证所有jvm实现都满足,且不保证向后兼容;
通过命令 java -X,如下

    -Xmixed           mixed mode execution (default)
    -Xint             interpreted mode execution only
    -Xbootclasspath:<directories and zip/jar files separated by :>
                      set search path for bootstrap classes and resources
    -Xbootclasspath/a:<directories and zip/jar files separated by :>
                      append to end of bootstrap class path
    -Xbootclasspath/p:<directories and zip/jar files separated by :>
                      prepend in front of bootstrap class path
    -Xdiag            show additional diagnostic messages
    -Xnoclassgc       disable class garbage collection
    -Xincgc           enable incremental garbage collection
    -Xloggc:<file>    log GC status to a file with time stamps
    -Xbatch           disable background compilation
    -Xms<size>        set initial Java heap size
    -Xmx<size>        set maximum Java heap size
    -Xss<size>        set java thread stack size
    -Xprof            output cpu profiling data
    -Xfuture          enable strictest checks, anticipating future default
    -Xrs              reduce use of OS signals by Java/VM (see documentation)
    -Xcheck:jni       perform additional checks for JNI functions
    -Xshare:off       do not attempt to use shared class data
    -Xshare:auto      use shared class data if possible (default)
    -Xshare:on        require using shared class data, otherwise fail.
    -XshowSettings    show all settings and continue
    -XshowSettings:all
                      show all settings and continue
    -XshowSettings:vm show all vm related settings and continue
    -XshowSettings:properties
                      show all property settings and continue
    -XshowSettings:locale
                      show all locale related settings and continue

3 非Stable参数(-XX)

非Stable参数(-XX),此类参数各个jvm实现会有所不同,将来可能会随时取消,需要慎重使用(但是,这些参数往往是非常有用的). 通过命令java -XX:+PrintFlagsFinal

[Global flags]
    uintx AdaptiveSizeDecrementScaleFactor          = 4                                   {product}
    uintx AdaptiveSizeMajorGCDecayTimeScale         = 10                                  {product}
    uintx AdaptiveSizePausePolicy                   = 0                                   {product}
    uintx AdaptiveSizePolicyCollectionCostMargin    = 50                                  {product}
    uintx AdaptiveSizePolicyInitializingSteps       = 20                                  {product}
    uintx AdaptiveSizePolicyOutputInterval          = 0                                   {product}
    uintx AdaptiveSizePolicyWeight                  = 10                                  {product}
    uintx AdaptiveSizeThroughPutPolicy              = 0                                   {product}
    uintx AdaptiveTimeWeight                        = 25                                  {product}
     bool AdjustConcurrency                         = false                               {product}
     bool AggressiveOpts                            = false                               {product}
     intx AliasLevel                                = 3                                   {C2 product}
     bool AlignVector                               = false                               {C2 product}
     intx AllocateInstancePrefetchLines             = 1                                   {product}
     intx AllocatePrefetchDistance                  = 192                                 {product}
     intx AllocatePrefetchInstr                     = 0                                   {product}
     intx AllocatePrefetchLines                     = 4                                   {product}
     intx AllocatePrefetchStepSize                  = 64                                  {product}
     intx AllocatePrefetchStyle                     = 1                                   {product}
     bool AllowJNIEnvProxy                          = false                               {product}
     bool AllowNonVirtualCalls                      = false                               {product}
     bool AllowParallelDefineClass                  = false                               {product}
     bool AllowUserSignalHandlers                   = false                               {product}
     bool AlwaysActAsServerClassMachine             = false                               {product}
     bool AlwaysCompileLoopMethods                  = false                               {product}
     bool AlwaysLockClassLoader                     = false                               {product}
     bool AlwaysPreTouch                            = false                               {product}
     bool AlwaysRestoreFPU                          = false                               {product}
     bool AlwaysTenure                              = false                               {product}
     bool AssertOnSuspendWaitFailure                = false                               {product}
     bool AssumeMP                                  = true                                {product}
     intx AutoBoxCacheMax                           = 128                                 {C2 product}
    uintx AutoGCSelectPauseMillis                   = 5000                                {product}
     intx BCEATraceLevel                            = 0                                   {product}
     intx BackEdgeThreshold                         = 100000                              {pd product}

也可以通过-XX:+PrintCommandLineFlags 。这个参数的作用是显示出VM初始化完毕后所有跟最初的默认值不同的参数及它们的值。
这个参数至少在Sun JDK 5上已经开始支持,Oracle/Sun JDK 6以及Oracle JDK 7上也可以使用。

再下来,-XX:+PrintFlagsInitial 。这个参数显示在处理参数之前所有可设置的参数及它们的值,然后直接退出程序。

本文来自:CSDN博客_如何查看jvm参数

感谢作者:CSDN博客_如何查看jvm参数

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