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Java HotSpot VM 参数

时间:2009-12-16 01:11来源:未知 作者:admin 点击:
Java HotSpot VM参数类别 以-X开头的参数是非标准的(不保证在所有的VM实现里都支持),并且在后续的JDK版本发布中修改后不作通告。 以-XX开头的参数是不稳定的,并且它也不推荐,只是临时使用。
  

Java HotSpot VM参数类别

  • 以-X开头的参数是非标准的(不保证在所有的VM实现里都支持),并且在后续的JDK版本发布中修改后不作通告。
  • 以-XX开头的参数是不稳定的,并且它也不推荐,只是临时使用。这些参数同样在修改后不作通告。

一些有用的-XX参数

这些参数的默认值在不同的平台上可能会有不同的值。不同平台的不同默认值列在描述里。

  • Boolean参数可以通过-XX:+<option>进行开启(true),通过-XX:-<option>进行关闭(false)
  • Numeric参数可以通过-XX:<option>=<number>进行设置数据可以包含'm'或'M'来表示兆,'k'或'K'表示千字节。'g'或'G'表示千兆。(例如, 32k等于32768)。
  • String参数可以通过-XX:<option>=<string>进行设置, 它通常用来指文件,路径或一些命令的列表。


行为参数

参数及默认值                                    描述

-XX:-AllowUserSignalHandlers  Do not complain if the application installs signal handlers. (Relevant to Solaris and Linux only.)

-XX:AltStackSize=16384 Alternate signal stack size (in Kbytes). (Relevant to Solaris only, removed from 5.0.)

-XX:-DisableExplicitGC Disable calls to System.gc(), JVM still performs garbage collection when necessary.

-XX:+FailOverToOldVerifier Fail over to old verifier when the new type checker fails. (Introduced in 6.)

-XX:+HandlePromotionFailure The youngest generation collection does not require a guarantee of full promotion of all live objects. (Introduced in 1.4.2update 11) [5.0 and earlier: false.]

-XX:+MaxFDLimit Bump the number of file descriptors to max. (Relevant to Solaris only.)

-XX:PreBlockSpin=10 Spin count variable for use with -XX:+UseSpinning. Controls themaximum spin iterations allowed before entering operating system threadsynchronization code. (Introduced in 1.4.2.)

-XX:-RelaxAccessControlCheck  Relax the access control checks in the verifier. (Introducedin 6.)

-XX:+ScavengeBeforeFullGC Do young generation GC prior to a full GC. (Introduced in 1.4.1.)

-XX:+UseAltSigs Use alternate signals instead of SIGUSR1 and SIGUSR2 for VMinternal signals. (Introduced in 1.3.1 update 9, 1.4.1. Relevant toSolaris only.)

-XX:+UseBoundThreads Bind user level threads to kernel threads. (Relevant toSolaris only.)

-XX:-UseConcMarkSweepGC Use concurrent mark-sweep collection for the old generation.(Introduced in 1.4.1)

-XX:+UseGCOverheadLimit Use a policy that limits the proportion of the VM's time that isspent in GC before an OutOfMemory error is thrown. (Introduced in 6.)

-XX:+UseLWPSynchronization Use LWP-based instead of thread based synchronization. (Introduced in 1.4.0. Relevant to Solaris only.)

-XX:-UseParallelGC Use parallel garbage collection for scavenges. (Introduced in 1.4.1)

-XX:-UseParallelOldGC Use parallel garbage collection for the full collections. Enablingthis option automatically sets -XX:+UseParallelGC. (Introduced in 5.0update 6.)

-XX:-UseSerialGC Use serial garbage collection. (Introduced in 5.0.)

-XX:-UseSpinning Enable naive spinning on Java monitor before entering operatingsystem thread synchronizaton code. (Relevant to 1.4.2 and 5.0 only.)[1.4.2, multi-processor Windows platforms: true]

-XX:+UseTLAB Use thread-local object allocation (Introduced in 1.4.0, known asUseTLE prior to that.) [1.4.2 and earlier, x86 or with -client: false]

-XX:+UseSplitVerifier Use the newtype checker with StackMapTable attributes. (Introduced in 5.0.)[5.0: false]

-XX:+UseThreadPriorities Use native thread priorities.

-XX:+UseVMInterruptibleIO Thread interrupt before or with EINTR for I/O operations results in OS_INTRPT. (Introduced in 6. Relevant to Solaris only.)


性能参数

参数及默认值                               描述

-XX:+AggressiveOpts Turn on point performance compiler optimizations that are expectedto be default in upcoming releases. (Introduced in 5.0 update 6.)

-XX:CompileThreshold=10000 Number of method invocations/branches before compiling [-client: 1,500]

-XX:LargePageSizeInBytes=4m Sets the large page size used for the Java heap. (Introduced in 1.4.0 update 1.) [amd64: 2m.]

-XX:MaxHeapFreeRatio=70 Maximum percentage of heap free after GC to avoid shrinking.

-XX:MaxNewSize=size Maximum size of new generation (in bytes). Since 1.4, MaxNewSize iscomputed as a function of NewRatio. [1.3.1 Sparc: 32m; 1.3.1 x86:2.5m.]

-XX:MaxPermSize=64m Size of the Permanent Generation.  [5.0 and newer: 64 bit VMs are scaled 30% larger; 1.4 amd64: 96m; 1.3.1 -client: 32m.]

-XX:MinHeapFreeRatio=40 Minimum percentage of heap free after GC to avoid expansion.

-XX:NewRatio=2 Ratio of new/old generation sizes. [Sparc -client: 8; x86 -server: 8; x86 -client: 12.]-client: 4 (1.3) 8 (1.3.1+), x86: 12]

-XX:NewSize=2.125m Default size of new generation (in bytes) [5.0 and newer: 64 bit VMs are scaled 30% larger; x86: 1m; x86, 5.0 and older: 640k]

-XX:ReservedCodeCacheSize=32m  Reserved code cache size (in bytes) - maximum code cache size.[Solaris 64-bit, amd64, and -server x86: 48m; in 1.5.0_06 and earlier,Solaris 64-bit and and64: 1024m.]

-XX:SurvivorRatio=8 Ratio of eden/survivor space size [Solaris amd64: 6; Sparc in 1.3.1: 25; other Solaris platforms in 5.0 and earlier: 32]

-XX:TargetSurvivorRatio=50 Desired percentage of survivor space used after scavenge.

-XX:ThreadStackSize=512 Thread Stack Size (in Kbytes). (0 means use default stack size)[Sparc: 512; Solaris x86: 320 (was 256 prior in 5.0 and earlier); Sparc64 bit: 1024; Linux amd64: 1024 (was 0 in 5.0 and earlier); allothers 0.]

-XX:+UseBiasedLocking Enable biased locking. For more details, see this tuningexample. (Introduced in 5.0 update 6.) [5.0: false]

-XX:+UseFastAccessorMethods Use optimized versions of Get<Primitive>Field.

-XX:-UseISM Use Intimate Shared Memory. [Not accepted for non-Solarisplatforms.] For details, see Intimate Shared Memory.

-XX:+UseLargePages Use large page memory. (Introduced in 5.0 update 5.) For details, see Java Support for Large MemoryPages.

-XX:+UseMPSS

Use Multiple Page Size Support w/4mb pages for the heap. Do not usewith ISM as this replaces the need for ISM. (Introduced in 1.4.0 update1, Relevant to Solaris 9 and newer.) [1.4.1and earlier: false


调试参数

参数及默认值                                                描述

 

-XX:-CITime Prints time spent in JIT Compiler. (Introduced in 1.4.0.)

-XX:ErrorFile=./hs_err_pid<pid>.log If an error occurs, save the error data to this file. (Introduced in 6.)

-XX:-ExtendedDTraceProbes Enable performance-impacting dtrace probes. (Introduced in 6.Relevant to Solaris only.)

-XX:-HeapDumpOnOutOfMemoryError Dump heap to file when java.lang.OutOfMemoryError is thrown. Manageable.(Introduced in 1.4.2 update 12, 5.0 update 7.)

-XX:OnError="<cmd args>;<cmd args>"  Run user-defined commands on fatal error. (Introduced in1.4.2 update 9.)

-XX:OnOutOfMemoryError="<cmd args>;
<cmd args>"
 Run user-defined commands when an OutOfMemoryError is first thrown. (Introduced in 1.4.2 update 12, 6)

-XX:-PrintClassHistogram Print a histogram of class instances on Ctrl-Break. Manageable. (Introduced in 1.4.2.) The jmap -histo

command provides equivalent functionality.
-XX:-PrintConcurrentLocks Print java.util.concurrent locks in Ctrl-Break thread dump. Manageable.(Introduced in 6.) The jstack -l command provides equivalent functionality.

-XX:-PrintCommandLineFlags Print flags that appeared on the command line. (Introduced in 5.0.)

-XX:-PrintCompilation Print message when a method is compiled.

-XX:-PrintGC Print messages at garbage collection. Manageable.

-XX:-PrintGC Details Print more details at garbage collection. Manageable. (Introduced in 1.4.0.)

-XX:-PrintGCTimeStamps Print timestamps at garbage collection. Manageable(Introduced in 1.4.0.)

-XX:-PrintTenuringDistribution Print tenuring age information.

-XX:-TraceClassLoading Trace loading of classes.

-XX:-TraceClassLoadingPreorder Trace all classes loaded in order referenced (not loaded). (Introduced in 1.4.2.)

-XX:-TraceClassResolution Trace constant pool resolutions.(Introduced in 1.4.2.)

-XX:-TraceClassUnloading Trace unloading of classes.

-XX:-TraceLoaderConstraints Trace recording of loader constraints. (Introduced in 6.)
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