JVM标准参数
命令行输入如下命令：
java
输出：
用法: java [-options] class [args...](执行类)或 java [-options] -jar jarfile [args...](执行 jar 文件)其中选项包括:-d32 使用 32 位数据模型 (如果可用)-d64 使用 64 位数据模型 (如果可用)-server 选择 "server" VM默认 VM 是 server,因为您是在服务器类计算机上运行。-cp <目录和 zip/jar 文件的类搜索路径>-classpath <目录和 zip/jar 文件的类搜索路径>用 : 分隔的目录, JAR 档案和 ZIP 档案列表, 用于搜索类文件。-D<名称>=<值>设置系统属性-verbose:[class|gc|jni]启用详细输出-version 输出产品版本并退出-version:<值>警告: 此功能已过时, 将在未来发行版中删除。需要指定的版本才能运行-showversion 输出产品版本并继续-jre-restrict-search | -no-jre-restrict-search警告: 此功能已过时, 将在未来发行版中删除。在版本搜索中包括/排除用户专用 JRE-? -help 输出此帮助消息-X 输出非标准选项的帮助-ea[:<packagename>...|:<classname>]-enableassertions[:<packagename>...|:<classname>]按指定的粒度启用断言-da[:<packagename>...|:<classname>]-disableassertions[:<packagename>...|:<classname>]禁用具有指定粒度的断言-esa | -enablesystemassertions启用系统断言-dsa | -disablesystemassertions禁用系统断言-agentlib:<libname>[=<选项>]加载本机代理库 <libname>, 例如 -agentlib:hprof另请参阅 -agentlib:jdwp=help 和 -agentlib:hprof=help-agentpath:<pathname>[=<选项>]按完整路径名加载本机代理库-javaagent:<jarpath>[=<选项>]加载 Java 编程语言代理, 请参阅 java.lang.instrument-splash:<imagepath>使用指定的图像显示启动屏幕有关详细信息, 请参阅 http://www.oracle.com/technetwork/java/javase/documentation/index.html。
JVM非标准参数
命令行输入如下命令：
java -X
输出：
-Xmixed 混合模式执行 (默认)-Xint 仅解释模式执行-Xbootclasspath:<用 : 分隔的目录和 zip/jar 文件>设置搜索路径以引导类和资源-Xbootclasspath/a:<用 : 分隔的目录和 zip/jar 文件>附加在引导类路径末尾-Xbootclasspath/p:<用 : 分隔的目录和 zip/jar 文件>置于引导类路径之前-Xdiag 显示附加诊断消息-Xnoclassgc 禁用类垃圾收集-Xincgc 启用增量垃圾收集-Xloggc:<file> 将 GC 状态记录在文件中 (带时间戳)-Xbatch 禁用后台编译-Xms<size> 设置初始 Java 堆大小-Xmx<size> 设置最大 Java 堆大小-Xss<size> 设置 Java 线程堆栈大小-Xprof 输出 cpu 配置文件数据-Xfuture 启用最严格的检查, 预期将来的默认值-Xrs 减少 Java/VM 对操作系统信号的使用 (请参阅文档)-Xcheck:jni 对 JNI 函数执行其他检查-Xshare:off 不尝试使用共享类数据-Xshare:auto 在可能的情况下使用共享类数据 (默认)-Xshare:on 要求使用共享类数据, 否则将失败。-XshowSettings 显示所有设置并继续-XshowSettings:all显示所有设置并继续-XshowSettings:vm 显示所有与 vm 相关的设置并继续-XshowSettings:properties显示所有属性设置并继续-XshowSettings:locale显示所有与区域设置相关的设置并继续-X 选项是非标准选项, 如有更改, 恕不另行通知。以下选项为 Mac OS X 特定的选项:-XstartOnFirstThread在第一个 (AppKit) 线程上运行 main() 方法-Xdock:name=<应用程序名称>"覆盖停靠栏中显示的默认应用程序名称-Xdock:icon=<图标文件的路径>覆盖停靠栏中显示的默认图标
JVM不稳定参数
命令行输入如下命令：
java -XX:+PrintFlagsFinal
输出：
[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 = 3 {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 = false {product}intx AutoBoxCacheMax = 128 {C2 product}uintx AutoGCSelectPauseMillis = 5000 {product}intx BCEATraceLevel = 0 {product}intx BackEdgeThreshold = 100000 {pd product}bool BackgroundCompilation = true {pd product}uintx BaseFootPrintEstimate = 268435456 {product}intx BiasedLockingBulkRebiasThreshold = 20 {product}intx BiasedLockingBulkRevokeThreshold = 40 {product}intx BiasedLockingDecayTime = 25000 {product}intx BiasedLockingStartupDelay = 4000 {product}bool BindGCTaskThreadsToCPUs = false {product}bool BlockLayoutByFrequency = true {C2 product}intx BlockLayoutMinDiamondPercentage = 20 {C2 product}bool BlockLayoutRotateLoops = true {C2 product}bool BranchOnRegister = false {C2 product}bool BytecodeVerificationLocal = false {product}bool BytecodeVerificationRemote = true {product}bool C1OptimizeVirtualCallProfiling = true {C1 product}bool C1ProfileBranches = true {C1 product}bool C1ProfileCalls = true {C1 product}bool C1ProfileCheckcasts = true {C1 product}bool C1ProfileInlinedCalls = true {C1 product}bool C1ProfileVirtualCalls = true {C1 product}bool C1UpdateMethodData = true {C1 product}intx CICompilerCount := 3 {product}bool CICompilerCountPerCPU = true {product}bool CITime = false {product}bool CMSAbortSemantics = false {product}uintx CMSAbortablePrecleanMinWorkPerIteration = 100 {product}intx CMSAbortablePrecleanWaitMillis = 100 {manageable}uintx CMSBitMapYieldQuantum = 10485760 {product}uintx CMSBootstrapOccupancy = 50 {product}bool CMSClassUnloadingEnabled = true {product}uintx CMSClassUnloadingMaxInterval = 0 {product}bool CMSCleanOnEnter = true {product}bool CMSCompactWhenClearAllSoftRefs = true {product}uintx CMSConcMarkMultiple = 32 {product}bool CMSConcurrentMTEnabled = true {product}uintx CMSCoordinatorYieldSleepCount = 10 {product}bool CMSDumpAtPromotionFailure = false {product}bool CMSEdenChunksRecordAlways = true {product}uintx CMSExpAvgFactor = 50 {product}bool CMSExtrapolateSweep = false {product}uintx CMSFullGCsBeforeCompaction = 0 {product}uintx CMSIncrementalDutyCycle = 10 {product}uintx CMSIncrementalDutyCycleMin = 0 {product}bool CMSIncrementalMode = false {product}uintx CMSIncrementalOffset = 0 {product}bool CMSIncrementalPacing = true {product}uintx CMSIncrementalSafetyFactor = 10 {product}uintx CMSIndexedFreeListReplenish = 4 {product}intx CMSInitiatingOccupancyFraction = -1 {product}uintx CMSIsTooFullPercentage = 98 {product}double CMSLargeCoalSurplusPercent = 0.950000 {product}double CMSLargeSplitSurplusPercent = 1.000000 {product}bool CMSLoopWarn = false {product}uintx CMSMaxAbortablePrecleanLoops = 0 {product}intx CMSMaxAbortablePrecleanTime = 5000 {product}uintx CMSOldPLABMax = 1024 {product}uintx CMSOldPLABMin = 16 {product}uintx CMSOldPLABNumRefills = 4 {product}uintx CMSOldPLABReactivityFactor = 2 {product}bool CMSOldPLABResizeQuicker = false {product}uintx CMSOldPLABToleranceFactor = 4 {product}bool CMSPLABRecordAlways = true {product}uintx CMSParPromoteBlocksToClaim = 16 {product}bool CMSParallelInitialMarkEnabled = true {product}bool CMSParallelRemarkEnabled = true {product}bool CMSParallelSurvivorRemarkEnabled = true {product}uintx CMSPrecleanDenominator = 3 {product}uintx CMSPrecleanIter = 3 {product}uintx CMSPrecleanNumerator = 2 {product}bool CMSPrecleanRefLists1 = true {product}bool CMSPrecleanRefLists2 = false {product}bool CMSPrecleanSurvivors1 = false {product}bool CMSPrecleanSurvivors2 = true {product}uintx CMSPrecleanThreshold = 1000 {product}bool CMSPrecleaningEnabled = true {product}bool CMSPrintChunksInDump = false {product}bool CMSPrintEdenSurvivorChunks = false {product}bool CMSPrintObjectsInDump = false {product}uintx CMSRemarkVerifyVariant = 1 {product}bool CMSReplenishIntermediate = true {product}uintx CMSRescanMultiple = 32 {product}uintx CMSSamplingGrain = 16384 {product}bool CMSScavengeBeforeRemark = false {product}uintx CMSScheduleRemarkEdenPenetration = 50 {product}uintx CMSScheduleRemarkEdenSizeThreshold = 2097152 {product}uintx CMSScheduleRemarkSamplingRatio = 5 {product}double CMSSmallCoalSurplusPercent = 1.050000 {product}double CMSSmallSplitSurplusPercent = 1.100000 {product}bool CMSSplitIndexedFreeListBlocks = true {product}intx CMSTriggerInterval = -1 {manageable}uintx CMSTriggerRatio = 80 {product}intx CMSWaitDuration = 2000 {manageable}uintx CMSWorkQueueDrainThreshold = 10 {product}bool CMSYield = true {product}uintx CMSYieldSleepCount = 0 {product}uintx CMSYoungGenPerWorker = 67108864 {pd product}uintx CMS_FLSPadding = 1 {product}uintx CMS_FLSWeight = 75 {product}uintx CMS_SweepPadding = 1 {product}uintx CMS_SweepTimerThresholdMillis = 10 {product}uintx CMS_SweepWeight = 75 {product}bool CheckEndorsedAndExtDirs = false {product}bool CheckJNICalls = false {product}bool ClassUnloading = true {product}bool ClassUnloadingWithConcurrentMark = true {product}intx ClearFPUAtPark = 0 {product}bool ClipInlining = true {product}uintx CodeCacheExpansionSize = 65536 {pd product}uintx CodeCacheMinimumFreeSpace = 512000 {product}bool CollectGen0First = false {product}bool CompactFields = true {product}intx CompilationPolicyChoice = 3 {product}ccstrlist CompileCommand = {product}ccstr CompileCommandFile = {product}ccstrlist CompileOnly = {product}intx CompileThreshold = 10000 {pd product}bool CompilerThreadHintNoPreempt = true {product}intx CompilerThreadPriority = -1 {product}intx CompilerThreadStackSize = 0 {pd product}uintx CompressedClassSpaceSize = 1073741824 {product}uintx ConcGCThreads = 0 {product}intx ConditionalMoveLimit = 3 {C2 pd product}intx ContendedPaddingWidth = 128 {product}bool ConvertSleepToYield = true {pd product}bool ConvertYieldToSleep = false {product}bool CrashOnOutOfMemoryError = false {product}bool CreateMinidumpOnCrash = false {product}bool CriticalJNINatives = true {product}bool DTraceAllocProbes = false {product}bool DTraceMethodProbes = false {product}bool DTraceMonitorProbes = false {product}bool Debugging = false {product}uintx DefaultMaxRAMFraction = 4 {product}intx DefaultThreadPriority = -1 {product}intx DeferPollingPageLoopCount = -1 {product}intx DeferThrSuspendLoopCount = 4000 {product}bool DeoptimizeRandom = false {product}bool DisableAttachMechanism = false {product}bool DisableExplicitGC = false {product}bool DisplayVMOutputToStderr = false {product}bool DisplayVMOutputToStdout = false {product}bool DoEscapeAnalysis = true {C2 product}bool DontCompileHugeMethods = true {product}bool DontYieldALot = false {pd product}ccstr DumpLoadedClassList = {product}bool DumpReplayDataOnError = true {product}bool DumpSharedSpaces = false {product}bool EagerXrunInit = false {product}intx EliminateAllocationArraySizeLimit = 64 {C2 product}bool EliminateAllocations = true {C2 product}bool EliminateAutoBox = true {C2 product}bool EliminateLocks = true {C2 product}bool EliminateNestedLocks = true {C2 product}intx EmitSync = 0 {product}bool EnableContended = true {product}bool EnableResourceManagementTLABCache = true {product}bool EnableSharedLookupCache = true {product}bool EnableTracing = false {product}uintx ErgoHeapSizeLimit = 0 {product}ccstr ErrorFile = {product}ccstr ErrorReportServer = {product}double EscapeAnalysisTimeout = 20.000000 {C2 product}bool EstimateArgEscape = true {product}bool ExitOnOutOfMemoryError = false {product}bool ExplicitGCInvokesConcurrent = false {product}bool ExplicitGCInvokesConcurrentAndUnloadsClasses = false {product}bool ExtendedDTraceProbes = false {product}ccstr ExtraSharedClassListFile = {product}bool FLSAlwaysCoalesceLarge = false {product}uintx FLSCoalescePolicy = 2 {product}double FLSLargestBlockCoalesceProximity = 0.990000 {product}bool FailOverToOldVerifier = true {product}bool FastTLABRefill = true {product}intx FenceInstruction = 0 {ARCH product}intx FieldsAllocationStyle = 1 {product}bool FilterSpuriousWakeups = true {product}ccstr FlightRecorderOptions = {product}bool ForceNUMA = false {product}bool ForceTimeHighResolution = false {product}intx FreqInlineSize = 325 {pd product}double G1ConcMarkStepDurationMillis = 10.000000 {product}uintx G1ConcRSHotCardLimit = 4 {product}uintx G1ConcRSLogCacheSize = 10 {product}intx G1ConcRefinementGreenZone = 0 {product}intx G1ConcRefinementRedZone = 0 {product}intx G1ConcRefinementServiceIntervalMillis = 300 {product}uintx G1ConcRefinementThreads = 0 {product}intx G1ConcRefinementThresholdStep = 0 {product}intx G1ConcRefinementYellowZone = 0 {product}uintx G1ConfidencePercent = 50 {product}uintx G1HeapRegionSize = 0 {product}uintx G1HeapWastePercent = 5 {product}uintx G1MixedGCCountTarget = 8 {product}intx G1RSetRegionEntries = 0 {product}uintx G1RSetScanBlockSize = 64 {product}intx G1RSetSparseRegionEntries = 0 {product}intx G1RSetUpdatingPauseTimePercent = 10 {product}intx G1RefProcDrainInterval = 10 {product}uintx G1ReservePercent = 10 {product}uintx G1SATBBufferEnqueueingThresholdPercent = 60 {product}intx G1SATBBufferSize = 1024 {product}intx G1UpdateBufferSize = 256 {product}bool G1UseAdaptiveConcRefinement = true {product}uintx GCDrainStackTargetSize = 64 {product}uintx GCHeapFreeLimit = 2 {product}uintx GCLockerEdenExpansionPercent = 5 {product}bool GCLockerInvokesConcurrent = false {product}uintx GCLogFileSize = 8192 {product}uintx GCPauseIntervalMillis = 0 {product}uintx GCTaskTimeStampEntries = 200 {product}uintx GCTimeLimit = 98 {product}uintx GCTimeRatio = 99 {product}uintx HeapBaseMinAddress = 2147483648 {pd product}bool HeapDumpAfterFullGC = false {manageable}bool HeapDumpBeforeFullGC = false {manageable}bool HeapDumpOnOutOfMemoryError = false {manageable}ccstr HeapDumpPath = {manageable}uintx HeapFirstMaximumCompactionCount = 3 {product}uintx HeapMaximumCompactionInterval = 20 {product}uintx HeapSizePerGCThread = 87241520 {product}bool IgnoreEmptyClassPaths = false {product}bool IgnoreUnrecognizedVMOptions = false {product}uintx IncreaseFirstTierCompileThresholdAt = 50 {product}bool IncrementalInline = true {C2 product}uintx InitialBootClassLoaderMetaspaceSize = 4194304 {product}uintx InitialCodeCacheSize = 2555904 {pd product}uintx InitialHeapSize := 134217728 {product}uintx InitialRAMFraction = 64 {product}uintx InitialSurvivorRatio = 8 {product}uintx InitialTenuringThreshold = 7 {product}uintx InitiatingHeapOccupancyPercent = 45 {product}bool Inline = true {product}ccstr InlineDataFile = {product}intx InlineSmallCode = 2000 {pd product}bool InlineSynchronizedMethods = true {C1 product}bool InsertMemBarAfterArraycopy = true {C2 product}intx InteriorEntryAlignment = 16 {C2 pd product}intx InterpreterProfilePercentage = 33 {product}bool JNIDetachReleasesMonitors = true {product}bool JavaMonitorsInStackTrace = true {product}intx JavaPriority10_To_OSPriority = -1 {product}intx JavaPriority1_To_OSPriority = -1 {product}intx JavaPriority2_To_OSPriority = -1 {product}intx JavaPriority3_To_OSPriority = -1 {product}intx JavaPriority4_To_OSPriority = -1 {product}intx JavaPriority5_To_OSPriority = -1 {product}intx JavaPriority6_To_OSPriority = -1 {product}intx JavaPriority7_To_OSPriority = -1 {product}intx JavaPriority8_To_OSPriority = -1 {product}intx JavaPriority9_To_OSPriority = -1 {product}bool LIRFillDelaySlots = false {C1 pd product}uintx LargePageHeapSizeThreshold = 134217728 {product}uintx LargePageSizeInBytes = 0 {product}bool LazyBootClassLoader = true {product}intx LiveNodeCountInliningCutoff = 40000 {C2 product}bool LogCommercialFeatures = false {product}intx LoopMaxUnroll = 16 {C2 product}intx LoopOptsCount = 43 {C2 product}intx LoopUnrollLimit = 60 {C2 pd product}intx LoopUnrollMin = 4 {C2 product}bool LoopUnswitching = true {C2 product}bool ManagementServer = false {product}uintx MarkStackSize = 4194304 {product}uintx MarkStackSizeMax = 536870912 {product}uintx MarkSweepAlwaysCompactCount = 4 {product}uintx MarkSweepDeadRatio = 1 {product}intx MaxBCEAEstimateLevel = 5 {product}intx MaxBCEAEstimateSize = 150 {product}uintx MaxDirectMemorySize = 0 {product}bool MaxFDLimit = true {product}uintx MaxGCMinorPauseMillis = 18446744073709551615 {product}uintx MaxGCPauseMillis = 18446744073709551615 {product}uintx MaxHeapFreeRatio = 100 {manageable}uintx MaxHeapSize := 2147483648 {product}intx MaxInlineLevel = 9 {product}intx MaxInlineSize = 35 {product}intx MaxJNILocalCapacity = 65536 {product}intx MaxJavaStackTraceDepth = 1024 {product}intx MaxJumpTableSize = 65000 {C2 product}intx MaxJumpTableSparseness = 5 {C2 product}intx MaxLabelRootDepth = 1100 {C2 product}intx MaxLoopPad = 11 {C2 product}uintx MaxMetaspaceExpansion = 5451776 {product}uintx MaxMetaspaceFreeRatio = 70 {product}uintx MaxMetaspaceSize = 18446744073709547520 {product}uintx MaxNewSize := 715653120 {product}intx MaxNodeLimit = 75000 {C2 product}uint64_t MaxRAM = 137438953472 {pd product}uintx MaxRAMFraction = 4 {product}intx MaxRecursiveInlineLevel = 1 {product}uintx MaxTenuringThreshold = 15 {product}intx MaxTrivialSize = 6 {product}intx MaxVectorSize = 32 {C2 product}uintx MetaspaceSize = 21807104 {pd product}bool MethodFlushing = true {product}uintx MinHeapDeltaBytes := 524288 {product}uintx MinHeapFreeRatio = 0 {manageable}intx MinInliningThreshold = 250 {product}intx MinJumpTableSize = 10 {C2 pd product}uintx MinMetaspaceExpansion = 339968 {product}uintx MinMetaspaceFreeRatio = 40 {product}uintx MinRAMFraction = 2 {product}uintx MinSurvivorRatio = 3 {product}uintx MinTLABSize = 2048 {product}intx MonitorBound = 0 {product}bool MonitorInUseLists = false {product}intx MultiArrayExpandLimit = 6 {C2 product}bool MustCallLoadClassInternal = false {product}uintx NUMAChunkResizeWeight = 20 {product}uintx NUMAInterleaveGranularity = 2097152 {product}uintx NUMAPageScanRate = 256 {product}uintx NUMASpaceResizeRate = 1073741824 {product}bool NUMAStats = false {product}ccstr NativeMemoryTracking = off {product}bool NeedsDeoptSuspend = false {pd product}bool NeverActAsServerClassMachine = false {pd product}bool NeverTenure = false {product}uintx NewRatio = 2 {product}uintx NewSize := 44564480 {product}uintx NewSizeThreadIncrease = 5320 {pd product}intx NmethodSweepActivity = 10 {product}intx NmethodSweepCheckInterval = 5 {product}intx NmethodSweepFraction = 16 {product}intx NodeLimitFudgeFactor = 2000 {C2 product}uintx NumberOfGCLogFiles = 0 {product}intx NumberOfLoopInstrToAlign = 4 {C2 product}intx ObjectAlignmentInBytes = 8 {lp64_product}uintx OldPLABSize = 1024 {product}uintx OldPLABWeight = 50 {product}uintx OldSize := 89653248 {product}bool OmitStackTraceInFastThrow = true {product}ccstrlist OnError = {product}ccstrlist OnOutOfMemoryError = {product}intx OnStackReplacePercentage = 140 {pd product}bool OptimizeFill = true {C2 product}bool OptimizePtrCompare = true {C2 product}bool OptimizeStringConcat = true {C2 product}bool OptoBundling = false {C2 pd product}intx OptoLoopAlignment = 16 {pd product}bool OptoScheduling = false {C2 pd product}uintx PLABWeight = 75 {product}bool PSChunkLargeArrays = true {product}intx ParGCArrayScanChunk = 50 {product}uintx ParGCDesiredObjsFromOverflowList = 20 {product}bool ParGCTrimOverflow = true {product}bool ParGCUseLocalOverflow = false {product}uintx ParallelGCBufferWastePct = 10 {product}uintx ParallelGCThreads = 4 {product}bool ParallelGCVerbose = false {product}uintx ParallelOldDeadWoodLimiterMean = 50 {product}uintx ParallelOldDeadWoodLimiterStdDev = 80 {product}bool ParallelRefProcBalancingEnabled = true {product}bool ParallelRefProcEnabled = false {product}bool PartialPeelAtUnsignedTests = true {C2 product}bool PartialPeelLoop = true {C2 product}intx PartialPeelNewPhiDelta = 0 {C2 product}uintx PausePadding = 1 {product}intx PerBytecodeRecompilationCutoff = 200 {product}intx PerBytecodeTrapLimit = 4 {product}intx PerMethodRecompilationCutoff = 400 {product}intx PerMethodTrapLimit = 100 {product}bool PerfAllowAtExitRegistration = false {product}bool PerfBypassFileSystemCheck = false {product}intx PerfDataMemorySize = 32768 {product}intx PerfDataSamplingInterval = 50 {product}ccstr PerfDataSaveFile = {product}bool PerfDataSaveToFile = false {product}bool PerfDisableSharedMem = false {product}intx PerfMaxStringConstLength = 1024 {product}intx PreInflateSpin = 10 {pd product}bool PreferInterpreterNativeStubs = false {pd product}intx PrefetchCopyIntervalInBytes = 576 {product}intx PrefetchFieldsAhead = 1 {product}intx PrefetchScanIntervalInBytes = 576 {product}bool PreserveAllAnnotations = false {product}bool PreserveFramePointer = false {pd product}uintx PretenureSizeThreshold = 0 {product}bool PrintAdaptiveSizePolicy = false {product}bool PrintCMSInitiationStatistics = false {product}intx PrintCMSStatistics = 0 {product}bool PrintClassHistogram = false {manageable}bool PrintClassHistogramAfterFullGC = false {manageable}bool PrintClassHistogramBeforeFullGC = false {manageable}bool PrintCodeCache = false {product}bool PrintCodeCacheOnCompilation = false {product}bool PrintCommandLineFlags = false {product}bool PrintCompilation = false {product}bool PrintConcurrentLocks = false {manageable}intx PrintFLSCensus = 0 {product}intx PrintFLSStatistics = 0 {product}bool PrintFlagsFinal := true {product}bool PrintFlagsInitial = false {product}bool PrintGC = false {manageable}bool PrintGCApplicationConcurrentTime = false {product}bool PrintGCApplicationStoppedTime = false {product}bool PrintGCCause = true {product}bool PrintGCDateStamps = false {manageable}bool PrintGCDetails = false {manageable}bool PrintGCID = false {manageable}bool PrintGCTaskTimeStamps = false {product}bool PrintGCTimeStamps = false {manageable}bool PrintHeapAtGC = false {product rw}bool PrintHeapAtGCExtended = false {product rw}bool PrintHeapAtSIGBREAK = true {product}bool PrintJNIGCStalls = false {product}bool PrintJNIResolving = false {product}bool PrintOldPLAB = false {product}bool PrintOopAddress = false {product}bool PrintPLAB = false {product}bool PrintParallelOldGCPhaseTimes = false {product}bool PrintPromotionFailure = false {product}bool PrintReferenceGC = false {product}bool PrintSafepointStatistics = false {product}intx PrintSafepointStatisticsCount = 300 {product}intx PrintSafepointStatisticsTimeout = -1 {product}bool PrintSharedArchiveAndExit = false {product}bool PrintSharedDictionary = false {product}bool PrintSharedSpaces = false {product}bool PrintStringDeduplicationStatistics = false {product}bool PrintStringTableStatistics = false {product}bool PrintTLAB = false {product}bool PrintTenuringDistribution = false {product}bool PrintTieredEvents = false {product}bool PrintVMOptions = false {product}bool PrintVMQWaitTime = false {product}bool PrintWarnings = true {product}uintx ProcessDistributionStride = 4 {product}bool ProfileInterpreter = true {pd product}bool ProfileIntervals = false {product}intx ProfileIntervalsTicks = 100 {product}intx ProfileMaturityPercentage = 20 {product}bool ProfileVM = false {product}bool ProfilerPrintByteCodeStatistics = false {product}bool ProfilerRecordPC = false {product}uintx PromotedPadding = 3 {product}uintx QueuedAllocationWarningCount = 0 {product}uintx RTMRetryCount = 5 {ARCH product}bool RangeCheckElimination = true {product}intx ReadPrefetchInstr = 0 {ARCH product}bool ReassociateInvariants = true {C2 product}bool ReduceBulkZeroing = true {C2 product}bool ReduceFieldZeroing = true {C2 product}bool ReduceInitialCardMarks = true {C2 product}bool ReduceSignalUsage = false {product}intx RefDiscoveryPolicy = 0 {product}bool ReflectionWrapResolutionErrors = true {product}bool RegisterFinalizersAtInit = true {product}bool RelaxAccessControlCheck = false {product}ccstr ReplayDataFile = {product}bool RequireSharedSpaces = false {product}uintx ReservedCodeCacheSize = 251658240 {pd product}bool ResizeOldPLAB = true {product}bool ResizePLAB = true {product}bool ResizeTLAB = true {pd product}bool RestoreMXCSROnJNICalls = false {product}bool RestrictContended = true {product}bool RewriteBytecodes = true {pd product}bool RewriteFrequentPairs = true {pd product}intx SafepointPollOffset = 256 {C1 pd product}intx SafepointSpinBeforeYield = 2000 {product}bool SafepointTimeout = false {product}intx SafepointTimeoutDelay = 10000 {product}bool ScavengeBeforeFullGC = true {product}intx SelfDestructTimer = 0 {product}uintx SharedBaseAddress = 34359738368 {product}ccstr SharedClassListFile = {product}uintx SharedMiscCodeSize = 122880 {product}uintx SharedMiscDataSize = 4194304 {product}uintx SharedReadOnlySize = 16777216 {product}uintx SharedReadWriteSize = 16777216 {product}bool ShowMessageBoxOnError = false {product}intx SoftRefLRUPolicyMSPerMB = 1000 {product}bool SpecialEncodeISOArray = true {C2 product}bool SplitIfBlocks = true {C2 product}intx StackRedPages = 1 {pd product}intx StackShadowPages = 20 {pd product}bool StackTraceInThrowable = true {product}intx StackYellowPages = 2 {pd product}bool StartAttachListener = false {product}intx StarvationMonitorInterval = 200 {product}bool StressLdcRewrite = false {product}uintx StringDeduplicationAgeThreshold = 3 {product}uintx StringTableSize = 60013 {product}bool SuppressFatalErrorMessage = false {product}uintx SurvivorPadding = 3 {product}uintx SurvivorRatio = 8 {product}intx SuspendRetryCount = 50 {product}intx SuspendRetryDelay = 5 {product}intx SyncFlags = 0 {product}ccstr SyncKnobs = {product}intx SyncVerbose = 0 {product}uintx TLABAllocationWeight = 35 {product}uintx TLABRefillWasteFraction = 64 {product}uintx TLABSize = 0 {product}bool TLABStats = true {product}uintx TLABWasteIncrement = 4 {product}uintx TLABWasteTargetPercent = 1 {product}uintx TargetPLABWastePct = 10 {product}uintx TargetSurvivorRatio = 50 {product}uintx TenuredGenerationSizeIncrement = 20 {product}uintx TenuredGenerationSizeSupplement = 80 {product}uintx TenuredGenerationSizeSupplementDecay = 2 {product}intx ThreadPriorityPolicy = 0 {product}bool ThreadPriorityVerbose = false {product}uintx ThreadSafetyMargin = 52428800 {product}intx ThreadStackSize = 1024 {pd product}uintx ThresholdTolerance = 10 {product}intx Tier0BackedgeNotifyFreqLog = 10 {product}intx Tier0InvokeNotifyFreqLog = 7 {product}intx Tier0ProfilingStartPercentage = 200 {product}intx Tier23InlineeNotifyFreqLog = 20 {product}intx Tier2BackEdgeThreshold = 0 {product}intx Tier2BackedgeNotifyFreqLog = 14 {product}intx Tier2CompileThreshold = 0 {product}intx Tier2InvokeNotifyFreqLog = 11 {product}intx Tier3BackEdgeThreshold = 60000 {product}intx Tier3BackedgeNotifyFreqLog = 13 {product}intx Tier3CompileThreshold = 2000 {product}intx Tier3DelayOff = 2 {product}intx Tier3DelayOn = 5 {product}intx Tier3InvocationThreshold = 200 {product}intx Tier3InvokeNotifyFreqLog = 10 {product}intx Tier3LoadFeedback = 5 {product}intx Tier3MinInvocationThreshold = 100 {product}intx Tier4BackEdgeThreshold = 40000 {product}intx Tier4CompileThreshold = 15000 {product}intx Tier4InvocationThreshold = 5000 {product}intx Tier4LoadFeedback = 3 {product}intx Tier4MinInvocationThreshold = 600 {product}bool TieredCompilation = true {pd product}intx TieredCompileTaskTimeout = 50 {product}intx TieredRateUpdateMaxTime = 25 {product}intx TieredRateUpdateMinTime = 1 {product}intx TieredStopAtLevel = 4 {product}bool TimeLinearScan = false {C1 product}bool TraceBiasedLocking = false {product}bool TraceClassLoading = false {product rw}bool TraceClassLoadingPreorder = false {product}bool TraceClassPaths = false {product}bool TraceClassResolution = false {product}bool TraceClassUnloading = false {product rw}bool TraceDynamicGCThreads = false {product}bool TraceGen0Time = false {product}bool TraceGen1Time = false {product}ccstr TraceJVMTI = {product}bool TraceLoaderConstraints = false {product rw}bool TraceMetadataHumongousAllocation = false {product}bool TraceMonitorInflation = false {product}bool TraceParallelOldGCTasks = false {product}intx TraceRedefineClasses = 0 {product}bool TraceSafepointCleanupTime = false {product}bool TraceSharedLookupCache = false {product}bool TraceSuspendWaitFailures = false {product}intx TrackedInitializationLimit = 50 {C2 product}bool TransmitErrorReport = false {product}bool TrapBasedNullChecks = false {pd product}bool TrapBasedRangeChecks = false {C2 pd product}intx TypeProfileArgsLimit = 2 {product}uintx TypeProfileLevel = 111 {pd product}intx TypeProfileMajorReceiverPercent = 90 {C2 product}intx TypeProfileParmsLimit = 2 {product}intx TypeProfileWidth = 2 {product}intx UnguardOnExecutionViolation = 0 {product}bool UnlinkSymbolsALot = false {product}bool Use486InstrsOnly = false {ARCH product}bool UseAES = true {product}bool UseAESIntrinsics = true {product}intx UseAVX = 2 {ARCH product}bool UseAdaptiveGCBoundary = false {product}bool UseAdaptiveGenerationSizePolicyAtMajorCollection = true {product}bool UseAdaptiveGenerationSizePolicyAtMinorCollection = true {product}bool UseAdaptiveNUMAChunkSizing = true {product}bool UseAdaptiveSizeDecayMajorGCCost = true {product}bool UseAdaptiveSizePolicy = true {product}bool UseAdaptiveSizePolicyFootprintGoal = true {product}bool UseAdaptiveSizePolicyWithSystemGC = false {product}bool UseAddressNop = true {ARCH product}bool UseAltSigs = false {product}bool UseAutoGCSelectPolicy = false {product}bool UseBMI1Instructions = true {ARCH product}bool UseBMI2Instructions = true {ARCH product}bool UseBiasedLocking = true {product}bool UseBimorphicInlining = true {C2 product}bool UseBoundThreads = true {product}bool UseBsdPosixThreadCPUClocks = true {product}bool UseCLMUL = true {ARCH product}bool UseCMSBestFit = true {product}bool UseCMSCollectionPassing = true {product}bool UseCMSCompactAtFullCollection = true {product}bool UseCMSInitiatingOccupancyOnly = false {product}bool UseCRC32Intrinsics = true {product}bool UseCodeCacheFlushing = true {product}bool UseCompiler = true {product}bool UseCompilerSafepoints = true {product}bool UseCompressedClassPointers := true {lp64_product}bool UseCompressedOops := true {lp64_product}bool UseConcMarkSweepGC = false {product}bool UseCondCardMark = false {C2 product}bool UseCountLeadingZerosInstruction = true {ARCH product}bool UseCountTrailingZerosInstruction = true {ARCH product}bool UseCountedLoopSafepoints = false {C2 product}bool UseCounterDecay = true {product}bool UseDivMod = true {C2 product}bool UseDynamicNumberOfGCThreads = false {product}bool UseFPUForSpilling = true {C2 product}bool UseFastAccessorMethods = false {product}bool UseFastEmptyMethods = false {product}bool UseFastJNIAccessors = true {product}bool UseFastStosb = true {ARCH product}bool UseG1GC = false {product}bool UseGCLogFileRotation = false {product}bool UseGCOverheadLimit = true {product}bool UseGCTaskAffinity = false {product}bool UseHeavyMonitors = false {product}bool UseHugeTLBFS = false {product}bool UseInlineCaches = true {product}bool UseInterpreter = true {product}bool UseJumpTables = true {C2 product}bool UseLWPSynchronization = true {product}bool UseLargePages = false {pd product}bool UseLargePagesInMetaspace = false {product}bool UseLargePagesIndividualAllocation = false {pd product}bool UseLockedTracing = false {product}bool UseLoopCounter = true {product}bool UseLoopInvariantCodeMotion = true {C1 product}bool UseLoopPredicate = true {C2 product}bool UseMathExactIntrinsics = true {C2 product}bool UseMaximumCompactionOnSystemGC = true {product}bool UseMembar = true {pd product}bool UseMontgomeryMultiplyIntrinsic = false {C2 product}bool UseMontgomerySquareIntrinsic = false {C2 product}bool UseMulAddIntrinsic = false {C2 product}bool UseMultiplyToLenIntrinsic = true {C2 product}bool UseNUMA = false {product}bool UseNUMAInterleaving = false {product}bool UseNewLongLShift = false {ARCH product}bool UseOSErrorReporting = false {pd product}bool UseOldInlining = true {C2 product}bool UseOnStackReplacement = true {pd product}bool UseOnlyInlinedBimorphic = true {C2 product}bool UseOprofile = false {product}bool UseOptoBiasInlining = true {C2 product}bool UsePSAdaptiveSurvivorSizePolicy = true {product}bool UseParNewGC = false {product}bool UseParallelGC := true {product}bool UseParallelOldGC = true {product}bool UsePerfData = true {product}bool UsePopCountInstruction = true {product}bool UseRDPCForConstantTableBase = false {C2 product}bool UseRTMDeopt = false {ARCH product}bool UseRTMLocking = false {ARCH product}bool UseSHA = false {product}bool UseSHA1Intrinsics = false {product}bool UseSHA256Intrinsics = false {product}bool UseSHA512Intrinsics = false {product}bool UseSHM = false {product}intx UseSSE = 4 {product}bool UseSSE42Intrinsics = true {product}bool UseSerialGC = false {product}bool UseSharedSpaces = false {product}bool UseSignalChaining = true {product}bool UseSquareToLenIntrinsic = false {C2 product}bool UseStoreImmI16 = false {ARCH product}bool UseStringDeduplication = false {product}bool UseSuperWord = true {C2 product}bool UseTLAB = true {pd product}bool UseThreadPriorities = true {pd product}bool UseTypeProfile = true {product}bool UseTypeSpeculation = true {C2 product}bool UseUnalignedLoadStores = true {ARCH product}bool UseVMInterruptibleIO = false {product}bool UseXMMForArrayCopy = true {product}bool UseXmmI2D = false {ARCH product}bool UseXmmI2F = false {ARCH product}bool UseXmmLoadAndClearUpper = true {ARCH product}bool UseXmmRegToRegMoveAll = true {ARCH product}bool VMThreadHintNoPreempt = false {product}intx VMThreadPriority = -1 {product}intx VMThreadStackSize = 1024 {pd product}intx ValueMapInitialSize = 11 {C1 product}intx ValueMapMaxLoopSize = 8 {C1 product}intx ValueSearchLimit = 1000 {C2 product}bool VerifyMergedCPBytecodes = true {product}bool VerifySharedSpaces = false {product}intx WorkAroundNPTLTimedWaitHang = 1 {product}uintx YoungGenerationSizeIncrement = 20 {product}uintx YoungGenerationSizeSupplement = 80 {product}uintx YoungGenerationSizeSupplementDecay = 8 {product}uintx YoungPLABSize = 4096 {product}bool ZeroTLAB = false {product}intx hashCode = 5 {product}
执行命令时把默认的执行参数打印出来：
java -XX:+PrintCommandLineFlags -version
Linux下执行结果：
-XX:InitialHeapSize=128123904 -XX:MaxHeapSize=2049982464 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGCjava version "1.8.0_152"Java(TM) SE Runtime Environment (build 1.8.0_152-b16)Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)
InitialHeapSize：初始化内存大小
MaxHeapSize：最大内存大小
+UseCompressedClassPointers：压缩指针
+UseCompressedOops：普通对象指针
默认情况下一个默认的64位系统，指针的长度默认应该是64位（8个字节），但是如果使用了+UseCompressedClassPointers，那么指针的长度就是4个字节
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