This document provides information on typical command-line options and environment variables that can affect the performance characteristics of the Java HotSpot Virtual Machine. Unless otherwise noted, all information in this document pertains to both the Java HotSpot Client VM and the Java HotSpot Server VM.
Users of JDKs older than 1.3.0 who wish to port to a Java HotSpot VM, should see Java HotSpot Equivalents of Exact VM flags.
Standard options recognized by the Java HotSpot VM are described on the Java Application Launcher reference pages for Windows, Solaris and Linux. This document deals exclusively with non-standard options recognized by the Java HotSpot VM:
Default values are listed for Java SE 6 for Solaris Sparc with -server. Some options may vary per architecture/OS/JVM version. Platforms with a differing default value are listed in the description.
Option and Default Value
Description
-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 1.4.2 update 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 the maximum spin iterations allowed before entering operating system thread synchronization code. (Introduced in 1.4.2.)
|
-XX:-RelaxAccessControlCheck |
Relax the access control checks in the verifier. (Introduced in 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 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 |
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 is spent 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. Enabling this option automatically sets -XX:+UseParallelGC. (Introduced in 5.0 update 6.)
|
-XX:-UseSerialGC |
Use serial garbage collection. (Introduced in 5.0.)
|
-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.)
|
Option and Default Value
Description
-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 Get<Primitive>Field.
|
-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.
|
Option and Default Value
Description
-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:HeapDumpPath=./java_pid<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="<cmd args>;<cmd args>" |
Run user-defined commands on fatal error. (Introduced in 1.4.2 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:-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.
|
<!-- =================== --><!-- END OF MAIN CONTENT --><!-- =================== --><!--stopindex--><!-- BEGIN D7 COMPONENT V.5 --><!--EndFragment-->
相关推荐
Sun JVM原理与内存管理
jvm 配置jvm参数 配置jvm参数
JVM参数设置,提供java虚拟机运行时的参数设置
如何配置jvm参数,并且调优,适合各路开发者,
常用jvm参数都在这张图中,参考起来方便,是国外大神整理的
JVM参数使用说明
JVM内存回收最全的手册书籍,详细介绍了各种内存回收算法,是Java程序员进阶的必备书籍
sunJVM的源代码
IBM JVM参数选项 虚拟机参数
(中英文)JVM 参数详解,用心整理成Excel文档。包含所有近100条JVM参数的详细说明及设置方法,中英文对照,极方便阅读。转载请标明我这的源地址:http://download.csdn.net/download/xiucaiyao/10257573
sunJVM的源代码8
sunJVM的源代码9
其二是非标准参数(-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; 其三是非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; 本文...
常用的JVM参数,适合于线上关键业务系统,通用参数设置经验
在/usr/local/apache-tomcat-5.5.23/bin目录下的catalina.sh 添加:JAVA_OPTS='-Xms512m -Xmx1024m' 要加“m”说明是MB,否则就是KB了,在启动tomcat时会报内存不足。 -Xms:初始值 -Xmx:最大值 ...
jvm 参数调优实践,有代码可供参考,详细调优比较!
linux 下jvm基本参数设置 查看linux jvm的设置基本命令
1、JVM参数推荐 2、Java运行时数据区 3、JVM内存模型 4、堆的内存划分 5、垃圾回收(GC) 6、JVM参数汇总
JVM参数调优 及 JAVA相关工具使用
sunJVM的源代码