jvm 性能调优 补充
一些常见的JVM 性能监测命令
1 window 上面安装的java 以后 默认 path 指向的C:\Program Files (x86)\Common Files\Oracle\Java\javapath 里面只有基本的命名 没有 ，如果需要使用 Java的 一些其他命令工具，需要吧 C:\Program Files\Java\jdk1.8.0_291\bin 加入path，并且位于 默认的 path 前面。
2 jps 能查询Java进程
-l 显示完整入口函数名
-m 显示方法参数
-v 显示jvm 参数
3 jstat -gcutil pid 查看 gc摘要
4 jinfo 查看和和调整jvm参数
jinfo -flag 参数名 pid
5 jmap -dump:format=b,file=d:\fileName.bin 打印堆栈道道指定文件 可以通过指定jvm参数，在内存溢出的时候dump heap（-XX:+HeapDumpOnOutOfMemoryError）
jmap -histo pid 查看 Java对象实例个数信息
6 jhat 分析heap dump
jhat dump.bin 分析 dump的 heap 文件（非常占用内存和cpu），分析完成后默认启动7000 端口，可以网页查看分析报告（可以使用oql查询语言）
7 jstack 生成线程快照
8 jconsole 提醒用户界面Java性能监测工具，能看到内存占用，线程执行情况，死锁检测，类实例数量 jvn 参数等等
8.1 jvisualvm 可视化jvm 性能监控工具 （怎么远程连接服务器查看jvm情况？）
8.2 JProfiler 收费的jvm可视化性能 分析工具
8.3 mat dump 文件可视化 分析工具
8.4 arthas（阿尔萨斯）阿里开源jvm监控软件(linux shell 命令行工具)
下载地址：https://arthas.aliyun.com/doc/download.html
Pinpoint、SkyWalking、Zipkin 分布式链路追踪
8.5 Prometheus（普罗米修斯） 监控报警工具，可以可以监控Java程序运行状态情况。（可以作为是否需要调优的依据之一）
8.6 gceasy 在线查看 gc 日志分析的 工具
https://gceasy.io/gc-index.jsp
JVM 参数格式说明
常见的JVM参数类型如下:
1.标准的jvm参数 -version -help
2.X非标准参数， -Xms -Xmx
3.XX不稳定参数， -XX:+PrintGC 设置这些参数会引起JVM性能差异
可能导致JVM性能提升，也可导致JVM异常而停止服务
注意事项:
-X和-XX参数可能随着JDK版本的变更而发生变化
在下一个版本中有些参数可以能会被废弃掉，
有些参数的功能会发生改变
但JDK官方不会通知开发者这些变化，需要使用者注意
XX参数数值类型
1.布尔类型 ,
如-XX:+PrintGCDetails
其中+和-
+代表开启功能
-代表关闭功能
2.KV 属性设置
如-XX:NewSize=512M
设置年轻代空间大小为512M
常见JVM 参数
9 -Xms jvm 初始内存大小（不指定 默认物理机内存的1/64）
10 -Xmx jvm 最大内存大小（不指定 默认物理机内存的1/4）
11 -XX:+HeapDumpOnOutOfMemoryError 内存溢出的时候 生成 堆内存日志
12：dump文件路径或者名称。如果不指定文件名，默认为：java_<pid>_<date>_<time>_heapDump.hprof
13 -XX:+PrintGCDetails 打印GC 日志
日志列简介说明
GC：表示进行了一次Minor GC，即从年轻代空间(包括 Eden 和 Survivor 区域)回收内存
Allocation Failure：在年轻代中没有足够的空间能够存储新的数据
Full GC (Ergonomics)：表示进行了一次Full GC，即清理整个堆空间(包含年轻代和老年代)
PSYoungGen: 1024K->1024K(1488K)：垃圾回收器是Paralle Scavenge，年轻代区GC前->GC后该区域已使用量，后面的1488表示该区域总量
ParOldGen: 4011K->4011K(4082K)老年代区，GC前->GC后该区域已使用量，后面的4082表示该区域总量
5032K->5032K(5899K)：GC前 -> GC后Java堆的使用量，后面的5899表示Java堆总量
Metaspace: 3117K->3117K(1056768K)：JDK8中取消了永久代，新增了一个叫元空间(Metaspace)的区域，对应的还是JVM规范中的方法区(主要存放一些class和元数据的信息)，该数据表示该区GC前后使用量
0.0118131 secs：暂停STW 时间，即GC的时间
Times: user=0.01 sys=0.01, real=0.01 secs：更为详细的时间占比统计
14 -Xloggc:路径 指定工程日志路径
15 -Xss 指定线程栈的大小
16 -Xmn 指定 新生代大小
-XX:NewSize：设置年轻代最小空间大小
-XX:MaxNewSize：设置年轻代最大空间大小
-Xmn等于 相当于这两个值相等并赋值
17 -XX:NewRatio：设置年轻代和老年代的比值。默认值-XX:NewRatio=2，表示年轻代与老年代比值为1:2，年轻代占整个堆大小的1/3
18 -XX:SurvivorRatio：设置年轻代中Eden区Survivor区的容量比值。默认值-XX:SurvivorRatio=8，表示Eden : Survivor0 : Survivor1 = 8 : 1 : 1
19 -XX:PermSize：设置永久代最小空间大小 1.8以前 有效 ，1.8 以后使用的元空间
20 -XX:MaxPermSize：设置永久代最大空间大小 1.8 以后使用的元空间
21 java -XX:+PrintFlagsFinal 打印有哪些非稳定参数 （ 700 多个）
C:\Users\ZHANGYUKUN>java -XX:+PrintFlagsFinal
[Global flags]
intx ActiveProcessorCount = -1 {product}
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 AggressiveHeap = false {product}
bool AggressiveOpts = false {product}
intx AliasLevel = 3 {C2 product}
bool AlignVector = true {C2 product}
intx AllocateInstancePrefetchLines = 1 {product}
intx AllocatePrefetchDistance = 256 {product}
intx AllocatePrefetchInstr = 0 {product}
intx AllocatePrefetchLines = 3 {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 := 4 {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 := 268435456 {product}
uintx InitialRAMFraction = 64 {product}
double InitialRAMPercentage = 1.562500 {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 = 4294967295 {product}
uintx MaxGCPauseMillis = 4294967295 {product}
uintx MaxHeapFreeRatio = 100 {manageable}
uintx MaxHeapSize := 4276092928 {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 = 15 {C2 product}
uintx MaxMetaspaceExpansion = 5451776 {product}
uintx MaxMetaspaceFreeRatio = 70 {product}
uintx MaxMetaspaceSize = 4294901760 {product}
uintx MaxNewSize := 1425014784 {product}
intx MaxNodeLimit = 75000 {C2 product}
uint64_t MaxRAM = 0 {pd product}
uintx MaxRAMFraction = 4 {product}
double MaxRAMPercentage = 25.000000 {product}
intx MaxRecursiveInlineLevel = 1 {product}
uintx MaxTenuringThreshold = 15 {product}
intx MaxTrivialSize = 6 {product}
intx MaxVectorSize = 16 {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}
double MinRAMPercentage = 50.000000 {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 := 89128960 {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 := 179306496 {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 = 10 {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 = 0 {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 = 6 {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 = 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 = 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 = 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 TraceExceptions = 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 UseAESCTRIntrinsics = 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 = false {ARCH product}
bool UseBiasedLocking = true {product}
bool UseBimorphicInlining = true {C2 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 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 = false {C2 product}
bool UseFastAccessorMethods = false {product}
bool UseFastEmptyMethods = false {product}
bool UseFastJNIAccessors = true {product}
bool UseFastStosb = false {ARCH product}
bool UseG1GC = false {product}
bool UseGCLogFileRotation = false {product}
bool UseGCOverheadLimit = true {product}
bool UseGCTaskAffinity = false {product}
bool UseGHASHIntrinsics = true {product}
bool UseHeavyMonitors = 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 UseLegacyJNINameEscaping = false {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 = false {pd product}
bool UseMontgomeryMultiplyIntrinsic = true {C2 product}
bool UseMontgomerySquareIntrinsic = true {C2 product}
bool UseMulAddIntrinsic = true {C2 product}
bool UseMultiplyToLenIntrinsic = true {C2 product}
bool UseNUMA = false {product}
bool UseNUMAInterleaving = false {product}
bool UseNewLongLShift = true {ARCH product}
bool UseOSErrorReporting = false {pd product}
bool UseOldInlining = true {C2 product}
bool UseOnStackReplacement = true {pd product}
bool UseOnlyInlinedBimorphic = true {C2 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}
intx UseSSE = 4 {product}
bool UseSSE42Intrinsics = true {product}
bool UseSerialGC = false {product}
bool UseSharedSpaces = false {product}
bool UseSignalChaining = true {product}
bool UseSquareToLenIntrinsic = true {C2 product}
bool UseStoreImmI16 = true {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 UseUTCFileTimestamp = true {product}
bool UseUnalignedLoadStores = false {ARCH product}
bool UseVMInterruptibleIO = false {product}
bool UseXMMForArrayCopy = false {product}
bool UseXmmI2D = true {ARCH product}
bool UseXmmI2F = true {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}
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}
22 java -X 打印有哪些非标准参数
C:\Users\ZHANGYUKUN>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>
设置引导类和资源的搜索路径
-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 分析数据
-Xfuture 启用最严格的检查，预计会成为将来的默认值
-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:system
（仅限 Linux）显示系统或容器
配置并继续
-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。
23 linux 上可以使用 grep查询 ，window 使用的 findStr 例如
linux：java -XX:+PrintFlagsFinal |grep GC
window：java -XX:+PrintFlagsFinal |findstr GC ，或者 java -XX:+PrintFlagsFinal |find "GC"
java -XX:+PrintFlagsFinal |find /C "GC" 可以统计行数，类似wc
24 互联网三高
高性能（高并发，低延时），高可用（不会因为一台服务宕机服务不可用），高拓展(动态伸缩的添加节点)
25 Java 对象分配过程
26 常见 Garbage Collection
27 对象引用压缩，32位的对象指针可以指向4GB的 数据，如果内存低于4GB可以压缩指针长度节省空间，默认JVM参数中是开启类指针压缩和对象指针压缩的。也就是默认开发环境指针占用4 个字节，32 位。
64位指针 可以容纳 4G*4G的数据，如果有一个云内存 4G*4G=16亿多G，大概相当于中国人均1个多G，全世界 60亿人。平均也有0.25G。如果给全世界人一起用，限制每个人最多使用4G内存云手机内存大概是够用的（平均4G，人要睡觉，有时差分布，要干别的事情，正常时候的内存负载低于4G，平均下来 1/20差不多够了，类似公司宽带，100人，人均100兆，需要1W兆，实际千兆就完全够了）
能耍的时候就一定要耍,不能耍的时候一定要学。
--天道酬勤,贵在坚持posted on 2022-04-17 17:46 zhangyukun 阅读(174) 评论(0) 编辑 收藏 举报
