JAVA HOTSPOT VM参数大全

Posted on feb. 2 2014

JAVA HOTSPOT VM参数大全

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Freaker与妖人 | 图解JVM在内存中申请对象及垃圾回收流程

2009-09-20

JAVA HOTSPOT VM参数大全

关键字: hotspot vm 参数 ///

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（本文JDK版本6.0）

SUN的JDK版本从1.3.1开始使用HotSpot虚拟机技术。 HotSpot是较新的Java虚拟机技术，用来代替JIT（Just in Time）技术，可以大大提高Java运行的性能。 Java原先是把源代码编译为字节码在虚拟机执行，这样执行速度较慢。而该技术将常用的部分代码编译为本地（原生，native）代码，这样显著提高了性能。用于服务器版和标准版的HotSpot有所不同。其他的Java虚拟机也有类似的技术。 HotSpot JVM 参数可以分为标准参数（standard options）和非标准参数（non-standard options）。标准参数相对稳定，在JDK未来的版本里不会有太大的改动。非标准参数则有因升级JDK而改变的可能。 标准参数： -client 使用Java HotSpot 客户端版VM。 -server 使用Java HotSpot 服务器版VM。如果是64位的JDK，默认只有server版，所以以上两个参数对64位版本JDK无效。 -agentlib: libname [=options] 加载本地代理函数库, e.g. -agentlib:jdwp=help -agentpath :pathname [=options] 使用给定的路径加载本地代理库。 -classpath classpath -cp classpath 不用说了。 -Dproperty =value 设置一个系统属性。 -d32 -d64 要求程序在32位或64位下跑，未来这个参数可能有变。 -enableassertions [:"..." | : ] -ea [:"..." | : ] 开启断言。 -disableassertions [:"..." | : ] -da [:"..." | : ] 关闭断言。 -enablesystemassertions - esa 启动所有系统类的断言。

-disablesystemassertions -dsa 关闭所有系统类的断言。 -jar 这个也没什么说的。 -javaagent :jarpath [=options] 加载Java 程序语言代理 -verbose:class 输出每个加载的类详细信息。 -verbose:gc 输出GC的详细信息。 -verbose:jni 输出本地方法接口的调用信息。 -version -help -? 不用说了。 -X 显示可用的非标准参数 非标准参数： -Xint 以解释模式运行。JVM不会使用HotSpot的新特性，不会将部分常用代码编译为本地代码，所有代码都以字节码的方式解释运行。你可以理解为使用JDK1.3.1以前的JIT方式运行程序。 -Xbatch 不使用后台编译。 -Xbootclasspath:bootclasspath 使用bootstrap classloader 加载指定路径的class或jar，这是种完全覆盖默认系统类加载的方案，慎用。 -Xbootclasspath/a:bootclasspath 将指定的classpath追加到默认的bootclasspath的后面加载 -Xbootclasspath/p:bootclasspath 将指定的classpath追加到默认的bootclasspath的前面加载 -Xcheck:jni 在调用JNI函数时做额外的检查。这个参数会降低JVM的执行性能。 -Xfuture 执行严格的class文件格式检查，不加这个参数，默认使用JDK1.1./ 版本的class格式检查方法。 -Xnoclassgc 禁用class垃圾收集。 -Xincgc 开启增量垃圾收集机制。默认为关闭。增量垃圾收集能减少因垃圾收集而引起的程序中断，它会在程序运行期间不定期地以并发的方式运行，在运行期间不会引起中断但是会减少分配给程序的cpu资源。 -Xloggc:file GC详情日志。效果如-verbose:gc ，不过这个可以输出到一个文件。除了-verbose:gc包含的信息，还有显示发生的时间。文件可以是远程的，但是考虑到网络延迟会引起JVM中断，一般建议使用本地文件， -Xms 分配的堆空间初始值： -Xms6291456 -Xms6144k -Xms6m -Xmx 分配的堆空间最大值： -Xmx83886080 -Xmx81920k -Xmx80m -Xprof 在运行程序时给出分析数据。适用于开发环境，不适用于生产环境。 -Xrs 减少JVM的操作系统信号的使用量。 -Xss 线程栈内存。 *非标准-XX参数

有三种-XX参数的形式：

Boolean 型的参数开启如 -XX:+
Numeric 型参数 -XX:
String 参数 -XX:

以下是-XX参数列表，本来想都翻译过来，但是发现一些技术术语如果硬是翻译可能会导致词不达意，因此大部分描述都保持原文。

参数名和默认值描述 -XX:-AllowUserSignalHandlers 允许使用用户自定义的信号处理器 (只对应Solaris和Linux) -XX:AltStackSize=16384 修改栈容量 (单位 Kb) (对应Solaris, JDK 5.0以后弃用) -XX:-DisableExplicitGC 禁止手动调用System.gc() -XX:+FailOverToOldVerifier 如果新的类型校验器验证失败使用旧版本的类型校验器 (开始于JDK6.) -XX:+HandlePromotionFailure The youngest generation collection does not require a guarantee of full promotion of all live objects. (Introduced in 1.4.2 update 11) [5.0 and earlier: false.] -XX:+MaxFDLimit 将文件描述符加到最大 (对应Solaris) -XX:PreBlockSpin=10 Spin count variable for use with -XX:+UseSpinning. Controls the maximum spin iterations allowed before entering operating system thread synchronization code. (Introduced in 1.4.2.) -XX:-RelaxAccessControlCheck 放宽类型校验机的准入控制(JDK6) -XX:+ScavengeBeforeFullGC 在full GC之前先做年轻代GC (开始于JDK1.4.1.) -XX:+UseAltSigs Use alternate signals instead of SIGUSR1 and SIGUSR2 for VM internal signals. (Introduced in 1.3.1 update 9, 1.4.1. Relevant to Solaris only.) -XX:+UseBoundThreads Bind user level threads to kernel threads. (Relevant to Solaris only.) -XX:-UseConcMarkSweepGC 使用并发的mark-sweep GC收集年老代 (始于JDK1.4.1) -XX:+UseGCOverheadLimit 使用一种限制VM做GC操作的时间所占比例过高的策略 (始于JDK6.) -XX:+UseLWPSynchronization 使用轻量级进程同步替代线程同步 (始于JDK1.4.0. Solaris相关) -XX:-UseParallelGC 使用并发平行GC(始于JDK1.4.1) -XX:-UseParallelOldGC 使用并发平行GC做 full GC. (始于JDK5.0 update 6.) -XX:-UseSerialGC 使用串行GC (始于JDK5.0.) -XX:-UseSpinning Enable naive spinning on Java monitor before entering operating system 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 as UseTLE prior to that.) [1.4.2 and earlier, x86 or with -client: false] -XX:+UseSplitVerifier Use the new type 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.)

参数名和默认值描述 -XX:+AggressiveOpts Turn on point performance compiler optimizations that are expected to 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 is computed 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); Sparc 64 bit: 1024; Linux amd64: 1024 (was 0 in 5.0 and earlier); all others 0.] -XX:+UseBiasedLocking Enable biased locking. For more details, see this tuning example . (Introduced in 5.0 update 6.) [5.0: false] -XX:+UseFastAccessorMethods Use optimized versions of GetField. -XX:-UseISM Use Intimate Shared Memory. [Not accepted for non-Solaris platforms.] 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 Memory Pages . -XX:+UseMPSS Use Multiple Page Size Support w/4mb pages for the heap. Do not use with ISM as this replaces the need for ISM. (Introduced in 1.4.0 update 1, Relevant to Solaris 9 and newer.) [1.4.1 and earlier: false] -XX:+StringCache Enables caching of commonly allocated strings. -XX:AllocatePrefetchLines=1 Number of cache lines to load after the last object allocation using prefetch instructions generated in JIT compiled code. Default values are 1 if the last allocated object was an instance and 3 if it was an array. -XX:AllocatePrefetchStyle=1 Generated code style for prefetch instructions. 0 - no prefetch instructions are generate/d/, 1 - execute prefetch instructions after each allocation, 2 - use TLAB allocation watermark pointer to gate when prefetch instructions are executed.

参数名和默认值描述 -XX:-CITime Prints time spent in JIT Compiler. (Introduced in 1.4.0.) -XX:ErrorFile=./hs_err_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:HeapDumpPath=./java_pid.hprof Path to directory or filename for heap dump. Manageable . (Introduced in 1.4.2 update 12, 5.0 update 7.) -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=";" Run user-defined commands on fatal error. (Introduced in 1.4.2 update 9.) -XX:OnOutOfMemoryError=";

" 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:-PrintGCDetails 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.) -XX:+PerfSaveDataToFile Saves jvmstat binary data on exit.

参考资料：

http://java.sun.com/javase/6/docs/technotes/tools/windows/java.html

http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp