我们为什么要对jvm做优化？
在本地开发环境中我们很少会遇到需要对jvm进行优化的需求，但是到了生产环境，我们可能将有下面的需求：
运行的应用“卡住了”，日志不输出，程序没有反应
服务器的CPU负载突然升高
在多线程应用下，如何分配线程的数量？
jvm的运行参数
在jvm中有很多的参数可以进行设置，这样可以让jvm在各种环境中都能够高效的运行。 绝大部分的参数保持默认即可。
三种参数类型
jvm的参数类型分为三类，分别是：
标准参数
-help
-version
-X参数 （非标准参数）
-Xint
-Xcomp
-XX参数（使用率较高）
-XX:newSize
-XX:+UseSerialGC
标准参数
jvm的标准参数，一般都是很稳定的，在未来的JVM版本中不会改变，可以使用java -help 检索出所有的标准参数。
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) -client 选择 "client" VM -server 选择 "server" VM 默认 VM 是 client. -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
查看JVM的版本
[root@node01 ~]# java ‐version java version "1.8.0_73" Java(TM) SE Runtime Environment (build 1.8.0_73‐b15) Java HotSpot(TM) 64‐Bit Server VM (build 25.73‐b15, mixed mode)
通过-D设置系统属性参数
public class TestJVM { public static void main(String[] args) { String str = System.getProperty("str"); if (str == null) { System.out.println("jvmTest"); } else { System.out.println(str); } } }
进行编译、测试
#编译
javac JvmTest.java
#运行
java JvmTest
#修改str值为JVM
java -Dstr=JVM JvmTest
-server与-client参数
可以通过-server或-client设置jvm的运行参数。
它们的区别是Server VM的初始堆空间会大一些，默认使用的是并行垃圾回收器，启动慢运行快。
Client VM相对来讲会保守一些，初始堆空间会小一些，使用串行的垃圾回收器，它的目标是为了让JVM的启动速度更快，但运行速度会比Serverm模式慢些。
JVM在启动的时候会根据硬件和操作系统自动选择使用Server还是Client类型的JVM。
32位操作系统
如果是Windows系统，不论硬件配置如何，都默认使用Client类型的JVM。
如果是其他操作系统上，机器配置有2GB以上的内存同时有2个以上CPU的话默认使用server模式，否则使用client模式。
64位操作系统
只有server类型，不支持client类型。
测试：
[root@node01 test]# java ‐client ‐showversion TestJVM java version "1.8.0_73" Java(TM) SE Runtime Environment (build 1.8.0_73‐b15) Java HotSpot(TM) 64‐Bit Server VM (build 25.141‐b15, mixed mode) itcast [root@node01 test]# java ‐server ‐showversion TestJVM java version "1.8.0_73" Java(TM) SE Runtime Environment (build 1.8.0_73‐b15) Java HotSpot(TM) 64‐Bit Server VM (build 25.141‐b15, mixed mode) itcast #由于机器是64位系统，所以不支持client模式
-X参数
JVM的-X参数是标椎参数，在不同的版本的JVM中，参数可能有所不同，可以通过java -X查看非标椎参数；
C:Usersjvm>java -X -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。
-Xint、-Xcomp、-Xmixed
在解释模式(interpreted mode)下，-Xint标记会强制JVM执行所有的字节码，当然这会降低运行速度，通常低10倍或更多。
-Xcomp参数与它（-Xint）正好相反，JVM在第一次使用时会把所有的字节码编译成本地代码，从而带来最大程度的优化。
然而，很多应用在使用-Xcomp也会有一些性能损失，当然这比使用-Xint损失的少，原因是-xcomp没有让JVM启用JIT编译器的全部功能。JIT编译器可以对是否需要编译做判断，如果所有代码都进行编译的话，对于一些只执行一次的代码就没有意义了。
-Xmixed是混合模式，将解释模式与编译模式进行混合使用，由jvm自己决定，这是jvm默认的模式，也是推荐使用的模式。
#注意：编译模式下，第一次执行会比解释模式下执行慢一些，注意观察。
#-Xint java -showversion -Xint JvmTest #-Xcomp java -showversion -Xcomp JvmTest #默认混合模式 java -showversion JvmTest
-XX参数
-XX参数也是非标准参数，主要用于jvm的调优和debug操作。
-XX参数的使用有2种方式，一种是boolean类型，一种是非boolean类型：
boolean类型
格式：-XX:[+-]
如：-XX:+DisableExplicitGC 表示禁用手动调用gc操作，也就是说调用System.gc()无效
非boolean类型
格式：-XX:
如：-XX:NewRatio=1 表示新生代和老年代的比值
测试：
java -showversion -XX:+DisableExplicitGC JvmTest
-Xms与-Xmx参数
-Xms与-Xmx分别是设置jvm的堆内存的初始大小和最大大小。
-Xmx2048m：等价于-XX:MaxHeapSize，设置JVM最大堆内存为2048M。
-Xms512m：等价于-XX:InitialHeapSize，设置JVM初始堆内存为512M。
适当的调整jvm的内存大小，可以充分利用服务器资源，让程序跑的更快。
测试：
java -Xms521m -Xmx1024m JvmTest
查看jvm的运行参数
有些时候我们需要查看jvm的运行参数，这个需求可能会存在2种情况：
第一，运行java命令时打印出运行参数；
第二，查看正在运行的java进程的参数；
2.6.1 运行java命令时打印参数
运行java命令时打印参数，需要添加java -XX:+PrintFlagsFinal -version参数即可。
参数有boolean类型和数字类型，值的操作符是=或:=，分别代表默认值和被修改的值。
[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 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} 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 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 = false {C1 product} intx CICompilerCount = 1 {product} bool CICompilerCountPerCPU = false {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 = 32768 {pd product} uintx CodeCacheMinimumFreeSpace = 512000 {product} bool CollectGen0First = false {product} bool CompactFields = true {product} intx CompilationPolicyChoice = 0 {product} ccstrlist CompileCommand = {product} ccstr CompileCommandFile = {product} ccstrlist CompileOnly = {product} intx CompileThreshold = 1500 {pd product} bool CompilerThreadHintNoPreempt = true {product} intx CompilerThreadPriority = -1 {product} intx CompilerThreadStackSize = 0 {pd product} uintx CompressedClassSpaceSize = 1073741824 {product} uintx ConcGCThreads = 0 {product} intx ContendedPaddingWidth = 128 {product} bool ConvertSleepToYield = true {pd product} bool ConvertYieldToSleep = 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 DontCompileHugeMethods = true {product} bool DontYieldALot = false {pd product} ccstr DumpLoadedClassList = {product} bool DumpReplayDataOnError = true {product} bool DumpSharedSpaces = false {product} bool EagerXrunInit = false {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} bool EstimateArgEscape = true {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 = 67108864 {product} bool IgnoreEmptyClassPaths = false {product} bool IgnoreUnrecognizedVMOptions = false {product} uintx IncreaseFirstTierCompileThresholdAt = 50 {product} uintx InitialBootClassLoaderMetaspaceSize = 2252800 {product} uintx InitialCodeCacheSize = 163840 {pd product} uintx InitialHeapSize := 16777216 {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 = 1000 {pd product} bool InlineSynchronizedMethods = true {C1 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} bool LogCommercialFeatures = false {product} bool ManagementServer = false {product} uintx MarkStackSize = 32768 {product} uintx MarkStackSizeMax = 4194304 {product} uintx MarkSweepAlwaysCompactCount = 4 {product} uintx MarkSweepDeadRatio = 5 {product} intx MaxBCEAEstimateLevel = 5 {product} intx MaxBCEAEstimateSize = 150 {product} uintx MaxDirectMemorySize = 0 {product} bool MaxFDLimit = true {product} uintx MaxGCMinorPauseMillis = 4294967295 {product} uintx MaxGCPauseMillis = 4294967295 {product} uintx MaxHeapFreeRatio = 70 {manageable} uintx MaxHeapSize := 268435456 {product} intx MaxInlineLevel = 9 {product} intx MaxInlineSize = 35 {product} intx MaxJNILocalCapacity = 65536 {product} intx MaxJavaStackTraceDepth = 1024 {product} uintx MaxMetaspaceExpansion = 4194304 {product} uintx MaxMetaspaceFreeRatio = 70 {product} uintx MaxMetaspaceSize = 4294901760 {product} uintx MaxNewSize := 89456640 {product} uint64_t MaxRAM = 1073741824 {pd product} uintx MaxRAMFraction = 4 {product} intx MaxRecursiveInlineLevel = 1 {product} uintx MaxTenuringThreshold = 15 {product} intx MaxTrivialSize = 6 {product} uintx MetaspaceSize = 12582912 {pd product} bool MethodFlushing = true {product} uintx MinHeapDeltaBytes := 131072 {product} uintx MinHeapFreeRatio = 40 {manageable} intx MinInliningThreshold = 250 {product} uintx MinMetaspaceExpansion = 262144 {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} 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 = true {pd product} bool NeverTenure = false {product} uintx NewRatio = 2 {product} uintx NewSize := 5570560 {product} uintx NewSizeThreadIncrease = 4096 {pd product} intx NmethodSweepActivity = 10 {product} intx NmethodSweepCheckInterval = 5 {product} intx NmethodSweepFraction = 3 {product} uintx NumberOfGCLogFiles = 0 {product} uintx OldPLABSize = 1024 {product} uintx OldPLABWeight = 50 {product} uintx OldSize := 11206656 {product} bool OmitStackTraceInFastThrow = true {product} ccstrlist OnError = {product} ccstrlist OnOutOfMemoryError = {product} intx OnStackReplacePercentage = 933 {pd product} intx OptoLoopAlignment = 16 {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 = 0 {product} bool ParallelGCVerbose = false {product} uintx ParallelOldDeadWoodLimiterMean = 50 {product} uintx ParallelOldDeadWoodLimiterStdDev = 80 {product} bool ParallelRefProcBalancingEnabled = true {product} bool ParallelRefProcEnabled = false {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 = -1 {product} intx PrefetchFieldsAhead = -1 {product} intx PrefetchScanIntervalInBytes = -1 {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 = false {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 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 = 33554432 {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 = false {pd product} bool RewriteFrequentPairs = false {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 = 0 {product} ccstr SharedClassListFile = {product} uintx SharedMiscCodeSize = 122880 {product} uintx SharedMiscDataSize = 2097152 {product} uintx SharedReadOnlySize = 12582912 {product} uintx SharedReadWriteSize = 12582912 {product} bool ShowMessageBoxOnError = false {product} intx SoftRefLRUPolicyMSPerMB = 1000 {product} intx StackRedPages = 1 {pd product} intx StackShadowPages = 4 {pd product} bool StackTraceInThrowable = true {product} intx StackYellowPages = 3 {pd product} bool StartAttachListener = false {product} intx StarvationMonitorInterval = 200 {product} bool StressLdcRewrite = false {product} uintx StringDeduplicationAgeThreshold = 3 {product} uintx StringTableSize = 1009 {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 = 0 {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 = false {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} bool TransmitErrorReport = false {product} bool TrapBasedNullChecks = false {pd product} intx TypeProfileArgsLimit = 2 {product} uintx TypeProfileLevel = 111 {pd 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 UseBoundThreads = 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 UseConcMarkSweepGC = false {product} bool UseCountLeadingZerosInstruction = true {ARCH product} bool UseCountTrailingZerosInstruction = true {ARCH product} bool UseCounterDecay = true {product} bool UseDynamicNumberOfGCThreads = false {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 UseInlineCaches = true {product} bool UseInterpreter = true {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 UseMaximumCompactionOnSystemGC = true {product} bool UseMembar = false {pd product} bool UseNUMA = false {product} bool UseNUMAInterleaving = false {product} bool UseNewLongLShift = false {ARCH product} bool UseOSErrorReporting = false {pd product} bool UseOnStackReplacement = true {pd product} bool UsePSAdaptiveSurvivorSizePolicy = true {product} bool UseParNewGC = false {product} bool UseParallelGC = false {product} bool UseParallelOldGC = false {product} bool UsePerfData = true {product} bool UsePopCountInstruction = true {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} intx UseSSE = 4 {product} bool UseSSE42Intrinsics = true {product} bool UseSerialGC = false {product} bool UseSharedSpaces = false {product} bool UseSignalChaining = true {product} bool UseStoreImmI16 = false {ARCH product} bool UseStringDeduplication = false {product} bool UseTLAB = true {pd product} bool UseThreadPriorities = true {pd product} bool UseTypeProfile = true {product} bool UseUTCFileTimestamp = true {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 = 0 {pd product} intx ValueMapInitialSize = 11 {C1 product} intx ValueMapMaxLoopSize = 8 {C1 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} null