| 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
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
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