Thursday, August 8, 2013

Default Values of JRockit's VM Options

Updated (09/19/2014):

You can also add -XX:+UnlockInternalVMOptions to the command line to access JVM internal flags.

To find out what the JRockit's default VM options are, you type:
  •  jdk-jr/bin/java -XX >JR_defaults.txt
Note that -XX is an alias for -Xprintflags in JRockit.

Default Values


Here are the output from this JRockit version:
  java version "1.6.0_37"
  Java(TM) SE Runtime Environment (build 1.6.0_37-b06)
  Oracle JRockit(R) (build R28.2.5-20-152429-1.6.0_37-20120927-1915-linux-x86_64, compiled mode)


Global:
        UnlockDiagnosticVMOptions = false (default, writeable)
                - Enable processing of flags relating to field diagnostics
        UnlockInternalVMOptions = false (default)
                - Enable processing of internal, unsupported flags
Class:
        FailOverToOldVerifier = true (default, writeable)
                - Fail over to old verifier when split verifier fails
        UseVerifierClassCache = true (default)
                - Try to cache java.lang.Class lookups for old verifier.
        UseClassGC = true (default)
                (Alias: -Xnoclassgc)
                - Allow GC of Java classes
Threads:
        UseThreadPriorities = false (default)
                - Use native thread priorities
        DeferThrSuspendLoopCount = 4000 (default, writeable)
                - Number of iterations in safepoint loop until we try blocking
        SafepointSpinBeforeYield = 2000 (default, writeable)
                - Number of iterations in safepoint loop until we yield instead
                  of pause (MP only)
        UseCompilerSafepoints = true (default)
                - Insert safepoint polls in compiled code
        DeferPollingPageLoopCount = -1 (default)
                - Number of iterations in safepoint loop before arming
                  safepoint poll page
        UseMembarForTransitions = false (default)
                - Use membar to serialize thread states.
        UseNativeLockProfiling = false (default)
                - Profile use of internal JVM monitors
        TrustPThreadStackInfo = false (default)
                - Trust information from pthreads about stack start and size
JNI:
        CheckJNICalls = false (default)
                - Verify all arguments to JNI calls
        AbortOnFailedJNICheck = true (default)
                - Used with CheckJNICalls. If true, abort the JVM upon first
                  JNI parameter error.
        ErrorOnFailedJNICheck = false (default)
                - Used with CheckJNICalls. If true, any errors will be
                  signalled through a java.lang.Error.
JDK:
        UseNewHashFunction = false (default)
                - Use HashMaps new hash function on jdks that does not do so by
                  default
        TreeMapNodeSize = 64 (default)
                - Size of entry array in each java.util.TreeMap node
        MaxDirectMemorySize = 0 (default)
                - Maximum total size of NIO direct-buffer allocations
        UseLazyStackTraces = true (default)
                - Generate stacktraces lazily for thrown Exceptions
        ShowInternalMethodsInStackTrace = false (default, writeable)
                - Show JVM internal code in java stacktraces.
        ExceptionTraceFilter = (null) (default)
                - Pattern that limits what exceptions are logged.
OS:
        ReduceSignalUsage = false (default)
                (Alias: -Xrs)
                - Reduce the use of OS signals in Java and/or the VM
        MaxFDLimit = true (default)
                - Maximize the available number of filedescriptors.
        MaxLargePageSize = 256M (default)
                - Use value as maximum size for large pages (if possible).
GC:
        UseLowAddressForHeap = true (default)
                - Use low 4Gb address space for Java heap if possible.
        UseLargePagesForHeap = false (default)
                - Attempt to use large page translation for the Java heap.
        ForceLargePagesForHeap = false (default)
                - Force the use of large page translation for the Java heap.
        CompressedRefs = false (default)
                (Alias: -XXcompressedRefs)
                - Use 32-bit java references on 64-bit OS - implies a heap
                  maximum of 4Gb (probably less)
        InitialHeapSize = 0 (default)
                (Alias: -Xms)
                - Initial size of Java Object heap
        MaxHeapSize = 0 (default)
                (Alias: -Xmx)
                - Maximum size of Java Object heap
        GCTimeRatio = 19 (default)
                - The ratio of time spent in garbage collection compared to
                  outside of garbage collection.
        GCTimePercentage = 0.000000 (default)
                - The percentage of time spent in garbage collection of total
                  run time.
        GCTrigger = 0 (default)
                (Alias: -XXgcTrigger)
                - The threshold of free heap before a concurrent GC is started
        ForceEarlyOC = true (default)
                - Force an early OC before old space is empty to avoid
                  promotion failed.
        ForceEarlyOCMaxPercentage = 5.000000 (default)
                - Maximum percentage of heap that is allowed to have left
                  before doing an early OC.
        ForceYCOnLargeAllocationFailed = false (default)
                - Force YC on a large allocation failure.
        UseNurseryEvacuation = false (default)
                - Try to evacuate the nursery when a promotion failed has
                  occured.
        DisableEvacuationToNursery = false (default)
                - Disallows evacuation to move objects to where the nursery is.
        NurseryPartsLimit = 10000 (default)
                - The maximum number of nursery parts we will allow before
                  forcing an early OC to fight fragmentation, or 0 for no
                  limit.
        SemiRefPostponedPacketSize = 492 (default)
                - The number of references in a postponed semiref packet.
        SemiRefPrefetchDistance = 0 (default)
                - The number of reference packet indexes to prefetch, or 0 for
                  no prefetch.
        FinalHandleParallelThreshold = -1 (default)
                - The minimum number of final handles needed to process them in
                  parallel.
        FinalHandlePacketSize = 200 (default)
                - The number of handles in a final handle packet.
        MaximumNurseryPercentage = 95 (default)
                - Sets the maximum size of the nursery relative to the amount
                  of free heap after the last old collection.
        AllowYCDuringOC = true (default)
                - Allow young collections during old collections.
        YcAlignAll = false (default)
                - Align all objects (with regards to YcAlignMaxSpill) during YC
        YcAlignMaxSpill = 40 (default)
                - Max spill allowed when aligning objects during YC.
        FullSystemGC = false (default)
                (Alias: -XXfullSystemGC)
                - Always run full GC (with full compaction) when System.gc() is
                  called
        AllowSystemGC = true (default)
                (Alias: -XXnoSystemGC)
                - Run a GC when System.gc() is called
        GcCardTableParts = 1024 (default)
                - Initial number of parts of the card table array
        GcBalancePrefetchDistance = 4 (default)
                - Prefetch distance in a GC balance system workpacket
        GcBalancePacketSize = 493 (default)
                - Packet size of GC balance system workpackets
        NumGenConPrecleaningIterations = 3 (default)
                - Number of precleaning iterations for gencon.
        AllowEmergencyParSweep = true (default)
                - Allow the OC to temporarily change concurrent sweep to
                  parallel if needed.
        UseCfsAdaptedYield = false (default)
                - Use a version of yield adapted for the CFS scheduler. Only
                  for use on CFS.
        TlaWasteLimit = 0 (default)
                (Alias: -XXlargeObjectLimit)
                - Internal. Use -XXtlaSize:wasteLimit instead.
        TlaMinSize = 0 (default)
                (Alias: -XXminBlockSize)
                - Internal. Use -XXtlaSize:min instead.
        TlaPreferredSize = 0 (default)
                - Internal. Use -XXtlaSize:preferred instead.
GC::Compaction:
        UseFullCompaction = false (default)
                - All compactions will be full compactions. Internal. Use
                  -XXcompaction:full instead.
        InternalCompactionPercentage = -1.000000 (default)
                - The percentage of the heap to compact for internal
                  compaction. Internal. Use -XXcompaction:internalPercentage
                  instead.
        ExternalCompactionPercentage = -1.000000 (default)
                - The percentage of the heap to compact for external
                  compaction. Internal. Use -XXcompaction:externalPercentage
                  instead.
        InitialCompactionPercentage = -1.000000 (default)
                - The initial percentage of the heap to compact, for both
                  internal and external compaction. Internal. Use
                  -XXcompaction:initialPercentage instead.
        UseCompaction = true (default)
                - Use compaction to reduce fragmentation. Internal. Use
                  -XXcompaction:enable instead.
        UseAbortableCompaction = false (default)
                - The compactions should be possible to abort. Internal. Use
                  -XXcompaction:abortable instead.
        NumCompactionHeapParts = 4096 (default)
                (Alias: -XXheapParts)
                - The number of heap parts in compaction heuristics. Internal.
                  Use -XXcompaction:heapParts instead.
        InitialExternalReservedHeap = 4M (default)
                - The initial size of the memory reserved by external
                  compaction. Internal. Use
                  -XXcompaction:initialExternalReservedHeap instead.
        UseFixedExternalReservedHeap = false (default)
                - The size of the memory reserved by external compaction is
                  fixed. Internal. Use
                  -XXcompaction:externalReservedHeapIsFixed instead.
        MaxCompactionReferences = 0 (default)
                (Alias: -XXcompactSetLimit)
                - The maximum number of references to store in compaction
                  before skipping. Internal. Use -XXcompaction:maxReferences
                  instead.
        MaxCompactionReferencesPerObject = 0 (default)
                (Alias: -XXcompactSetLimitPerObject)
                - The maximum number of references to store per object in
                  compaction. Internal. Use
                  -XXcompaction:maxReferencesPerObject instead.
        InternalCompactionParts = -1 (default)
                (Alias: -XXinternalCompactRatio)
                - Deprecated. Use -XXcompaction:internalPercentage instead.
        ExternalCompactionParts = -1 (default)
                (Alias: -XXexternalCompactRatio)
                - Deprecated. Use -XXcompaction:externalPercentage instead.
Object allocation:
        UseAllocPrefetch = true (default)
                - Use prefetch on object allocation
        RedoAllocPrefetch = true (default)
                - Do prefetch on object allocation from start of the allocated
                  object
        AllocPrefetchLineLength = -1 (default)
                - Line length for allocation prefetch
        AllocPrefetchDistance = -1 (default)
                - Distance for allocation prefetch
        AllocChunkSize = -1 (default)
                - Size of chunks to clear/prefetch
Javalock:
        UseLockProfiling = false (default)
                - Enable Java lock profiling.
        ThinLockContendedSpinCount = -1 (default)
                - Number of spins between each poll when acquiring a thin lock
        ThinLockContendedPollCount = -1 (default)
                - Number of polls between each short nap when acquiring a thin
                  lock
        ThinLockConvertToFatThreshold = -1 (default)
                - Number of of short naps before converting thin lock to fat
        FatLockContendedSpinCount = -1 (default)
                - Number of spins between each poll when acquiring a fat lock
        FatLockContendedPollCount = -1 (default)
                - Number of polls between each short nap when acquiring a fat
                  lock
        MonitorContendedSpinCount = -1 (default)
                - Number of spins between each poll when acquiring a monitor
                  lock
        MonitorContendedPollCount = -1 (default)
                - Number of polls between each short nap when acquiring a
                  monitor lock
        UseFatLockDeflation = true (default)
                - Try to deflate fat locks to thin
        FatLockDeflationThreshold = 50 (default)
                - Number of uncontended entries on lock before deflation occurs
        UseLockQueueLength = true (default)
                - Make threads go to sleep if contention exceeds # cpus
        UseFatSpin = true (default)
                (Alias: -XXdisableFatSpin)
                - Should we spin-try then acquiring a fat lock
        UseAdaptiveFatSpin = false (default)
                - Should we use adaptive spinning acquiring a fat lock
        UseThreadContentionMonitoring = true (default)
                - Allow thread contention monitoring
JavaLock::LazyUnlocking:
        UseLazyUnlocking = true (default)
                (Alias: -XXlazyUnlocking)
                - Enable lazy unlocking
        UseLazyUnlockingInJIT = true (default)
                - Use lazy locks in JIT code
        UseLazyUnlockingClassBan = true (default)
                - Use class banning
        UseLazyUnlockingTransferClassBan = true (default)
                - Use transfer class banning
JFR:
        FlightRecorder = true (default)
                - Enable flightrecorder
        FlightRecorderOptions = (null) (default)
                - Flight recorder arguments
        StartFlightRecording = (null) (default)
                - Start a Flight recording with args. Equivalent to using
                  "start_flightrecording".
Code memory:
        CodeBlockAbsorbtionSize = 32 (default)
                - Maximum extra size allowed for fitting code memory chunks
        FreeEmptyCodeBlocks = true (default)
                - Free unused code memory
        UseLargePagesForCode = false (default)
                - Attempt to use large page translation compiled code.
        MaxCodeMemory = 0 (default)
                - Maximum amount of memory used for generated code
        ReserveCodeMemory = true (default)
                - Reserve all memory for code at startup
        UseCodeGC = true (default)
                - Allow GC of discarded compiled code
        CodeGCThreshold = 0 (default)
                - Released byte threshold for initiating a code GC
        CodeGCReclaimThreshold = 0 (default)
                - Released byte threshold before compiler attempts to reclaim
                  unused code space
        CodeGCUseReclaim = true (default)
                - Should Code GC attempt reclamation of unused code memory
        CodeGCTaskInterval = 5 (default)
                - Interval in secs between background scans for unused code
                  blocks
Compiler broker:
        MaxOptQueueLength = 0 (default)
                - Maximum allowed optimization queue length before JIT thread
                  helps generate code
        OptThreads = 1 (default)
                - Number of background optimization threads
        JITThreads = 1 (default)
                - Number of background JIT threads
        JITThreadPrio = 5 (default)
                - Priority of background JIT threads
        OptThreadPrio = 5 (default)
                - Priority of background optimization threads
        DisableOptsAfter = -1 (default)
                (Alias: -Xnoopt)
                - Disable optimizations after n seconds
Compiler:
        PreOpt = false (default)
                - Optimize all code on jit (first generation)
        UseCallProfiling = false (default)
                - Use call profiling on unoptimized code
        StrictFP = false (default)
                (Alias: -Xstrictfp)
                - Force strict FP for all methods
        CheckStacks = false (default)
                (Alias: -Xcheckedstacks)
                - Do explicit checks for stack overflow
        DevirtualizeAlways = false (default)
                - Forces devirtualization in jitted code
        UseStringCache = false (default)
                - Cache common arrays used in String constructor
        MethodCodeAlignment = 32 (default)
                - Byte alignment for start of method code
        UseInlineObjectAlloc = true (default)
                - Generate inlined object allocation code.
        UseSafeTimer = false (default)
                - Use fast, signal based timer for System.currentTimeMillis.
        UseOldLockMatching = false (default)
                - Compatibility mode lock matching
JVMTI:
        JavaDebug = false (default)
                (Alias: -Xdebug)
                - Enable java debugging
Management:
        DisableAttachMechanism = false (default)
                - Disable mechanism that allows tools to attach to this VM
        CrashOnOutOfMemoryError = false (default, writeable)
                - Crash JVM process on OutOfMemory
        ExitOnOutOfMemoryError = false (default, writeable)
                - Terminate JVM process on OutOfMemory
        ExitOnOutOfMemoryErrorExitCode = 51 (default, writeable)
                - Exit code for termination of  JVM process on OutOfMemory
        HeapDiagnosticsOnOutOfMemoryError = false (default, writeable)
                - Print Java heap diagnostics on OutOfMemory
        HeapDiagnosticsPath = (null) (default, writeable)
                - When HeapDiagnosticsOnOutOfMemoryError is on, the path
                  (filename or directory) of the dump file (defaults to
                  jrockit_.oomdiag in the working directory)
        HeapDumpOnOutOfMemoryError = false (default, writeable)
                - Dump Java heap to a hprof binary format file on OutOfMemory
        HeapDumpOnCtrlBreak = false (default)
                - Dump heap to file in Ctrl-Break handler
        HeapDumpPath = (null) (default, writeable)
                - When HeapDumpOnOutOfMemoryError is on, the path (filename or
                  directory) of the dump file (defaults to jrockit_.hprof
                  in the working directory)
        SegmentedHeapDumpThreshold = 2G (default, writeable)
                - Generate a segmented heap dump (JAVA PROFILE 1.0.2 format)
                  when the heap usage is larger than this
        HeapDumpSegmentSize = 1G (default)
                - Approximate segment size when generating a segmented heap
                  dump
        StartMemleakOnPort = 0 (default, writeable)
                (Alias: -XXmemleak)
                - Listen for memleak connections on this port (0 for default)
        FlightRecordingDumpOnUnhandledException = false (default, writeable)
                - Generate a Flight Recording dump when a thread is terminated
                  due to an unhandled exception
        FlightRecordingDumpPath = (null) (default, writeable)
                - When FlightRecordingDumpOnUnhandledException is on, the path
                  (filename or directory) of the dump file (defaults to
                  jrockit__.jfr in the working directory)
Runtime:
        AbortOnCrash = false (default, writeable)
                - Abort the JVM in case of an crash.
        DumpOnCrash = true (default, writeable)
                - Generate a dump of the JVM state in case of a crash.
        CoreOnCrash = true (default, writeable)
                - Generate a core dump file of the JVM state in case of a
                  crash.
        WaitOnCrash = false (default, writeable)
                - Wait for user debugger attach in case of a crash.
        AbortOnAssert = true (default, writeable)
                - Abort JVM on assertion
        CrashOnAssert = false (default, writeable)
                - Crash dump the JVM on assertion
        WaitOnAssert = false (default, writeable)
                - Spin and wait JVM on assertion
        NumaMemoryPolicy = (null) (default)
                - Numa memory policy (interleave, preferredlocal, strictlocal)
        BindToNumaNodes = (null) (default)
                - Bind process to Numa nodes
        BindToCPUs = (null) (default)
                - Bind process to CPUs
        UseFastTime = true (default)
                - Force/disable usage of hardware platform support for fast
                  time
        UseJNIPinning = true (default)
                - Use pinning for Objects in call to GetPrimitiveArrayCritical
                  etc

See Also

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