"-XX:+PrintFlagsFinal" - Print JVM Options

This section describes the '-XX:+PrintFlagsFinal' JVM option, which prints all options and their values used by the JVM.

If want to know what are default options used by the JVM, you can use the "-XX:+PrintFlagsFinal" option to print them out:

C:\herong>java -XX:+PrintFlagsFinal GarbageCollection

[Global flags]
ccstrlist AOTLibrary                               =
      int ActiveProcessorCount                     = -1
    uintx AdaptiveSizeDecrementScaleFactor         = 4
    uintx AdaptiveSizeMajorGCDecayTimeScale        = 10
    uintx AdaptiveSizePolicyCollectionCostMargin   = 50
    uintx AdaptiveSizePolicyInitializingSteps      = 20
    uintx AdaptiveSizePolicyOutputInterval         = 0
    uintx AdaptiveSizePolicyWeight                 = 10
    uintx AdaptiveSizeThroughPutPolicy             = 0
    uintx AdaptiveTimeWeight                       = 25
     bool AggressiveHeap                           = false
     intx AliasLevel                               = 3
     bool AlignVector                              = false
    ccstr AllocateHeapAt                           =
     intx AllocateInstancePrefetchLines            = 1
     intx AllocatePrefetchDistance                 = 192
     intx AllocatePrefetchInstr                    = 3
     intx AllocatePrefetchLines                    = 4
     intx AllocatePrefetchStepSize                 = 64
     intx AllocatePrefetchStyle                    = 1
     bool AllowJNIEnvProxy                         = false
     bool AllowParallelDefineClass                 = false
     bool AllowUserSignalHandlers                  = false
     bool AllowVectorizeOnDemand                   = true
     bool AlwaysActAsServerClassMachine            = false
     bool AlwaysCompileLoopMethods                 = false
     bool AlwaysLockClassLoader                    = false
     bool AlwaysPreTouch                           = false
     bool AlwaysRestoreFPU                         = false
     bool AlwaysTenure                             = false
     intx ArrayCopyLoadStoreMaxElem                = 8
     bool AssertOnSuspendWaitFailure               = false
     intx AutoBoxCacheMax                          = 128
     intx BCEATraceLevel                           = 0
     bool BackgroundCompilation                    = true
   size_t BaseFootPrintEstimate                    = 268435456
     intx BiasedLockingBulkRebiasThreshold         = 20
     intx BiasedLockingBulkRevokeThreshold         = 40
     intx BiasedLockingDecayTime                   = 25000
     intx BiasedLockingStartupDelay                = 0
     bool BindGCTaskThreadsToCPUs                  = false
     bool BlockLayoutByFrequency                   = true
     intx BlockLayoutMinDiamondPercentage          = 20
     bool BlockLayoutRotateLoops                   = true
     bool BranchOnRegister                         = false
     bool BytecodeVerificationLocal                = false
     bool BytecodeVerificationRemote               = true
     bool C1OptimizeVirtualCallProfiling           = true
     bool C1ProfileBranches                        = true
	 ...

Table of Contents

 About This Book

 Heap Memory Area and Size Control

JVM Garbage Collection Logging

 Garbage Collection Demo Program

 Garbage Collection Logging Options

 "-Xlog:gc" - Default GC Logging Level: INFO

 "-Xlog:gc=trace" - Lowest GC Logging Level: TRACE

 "-Xlog:gc+heap=trace" - GC+HEAP Log Messages

 "-Xlog:gc*=trace" - Maximum GC Logging

"-XX:+PrintFlagsFinal" - Print JVM Options

 Introduction of Garbage Collectors

 Serial Collector - "+XX:+UseSerialGC"

 Parallel Collector - "+XX:+UseParallelGC"

 Concurrent Mark-Sweep (CMS) Collector - "+XX:+UseConcMarkSweepGC"

 Garbage First (G1) Collector - "+XX:+UseG1GC"

 The Z Garbage Collector (ZGC) - "+XX:+UseZGC"

 Object References and Garbage Collection

 Garbage Collection Performance Test Program

 Performance Tests on Serial Collector

 Performance Tests on Parallel collector

 Performance Tests on Concurrent collector

 Performance Tests on G1 collector

 Garbage Collection Performance Test Summary

 References

 Full Version in PDF/EPUB