隨筆-37  評論-3271  文章-0  trackbacks-0

          在java進程后追加-X參數可看到對應的擴展參數,命令:java -X

          下面列出了各個廠商的輸出,可以看到IBM的幫助最詳細而且是中文的,有意思。

          另外JRockit還支持一個 -XX參數,其輸出如下:

          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
          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.
          OS:
                  ReduceSignalUsage = false (default)
                          (Alias: -Xrs)
                          - Reduce the use of OS signals in Java and/or the VM
                  MaxRecvBufferSize = 65536 (default)
                          - Maximum size of byte buffer sent to recv
                  MaxLargePageSize = 0 (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.
                  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.
                  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 = 16 (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 = false (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
          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.
                  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_<pid>.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_<pid>.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_<pid>_<thread id>.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
          

           

          下面是-X的輸出:

           

          SUN JDK 6

              -Xmixed           mixed mode execution (default)
              -Xint             interpreted mode execution only
              -Xbootclasspath:<directories and zip/jar files separated by ;>
                                set search path for bootstrap classes and resources
              -Xbootclasspath/a:<directories and zip/jar files separated by ;>
                                append to end of bootstrap class path
              -Xbootclasspath/p:<directories and zip/jar files separated by ;>
                                prepend in front of bootstrap class path
              -Xnoclassgc       disable class garbage collection
              -Xincgc           enable incremental garbage collection
              -Xloggc:<file>    log GC status to a file with time stamps
              -Xbatch           disable background compilation
              -Xms<size>        set initial Java heap size
              -Xmx<size>        set maximum Java heap size
              -Xss<size>        set java thread stack size
              -Xprof            output cpu profiling data
              -Xfuture          enable strictest checks, anticipating future default
              -Xrs              reduce use of OS signals by Java/VM (see documentation)
              -Xcheck:jni       perform additional checks for JNI functions
              -Xshare:off       do not attempt to use shared class data
              -Xshare:auto      use shared class data if possible (default)
              -Xshare:on        require using shared class data, otherwise fail.
          
          The -X options are non-standard and subject to change without notice.
          

          JRockit JDK 6

              -Xbootclasspath:<directories and zip/jar files separated by ;>
                        set search path for bootstrap classes and resources
              -Xbootclasspath/a:<directories and zip/jar files separated by ;> 
                        append to end of bootstrap class path
              -Xbootclasspath/p:<directories and zip/jar files separated by ;>
                        prepend in front of bootstrap class path
              -Xgcprio:[throughput|pausetime|deterministic]
          	      sets priority for the garbage collector (gc)
          		  throughput	optimizes the gc behavior to achieve optimal
                                          throughput (default in server mode)
          		  pausetime	optimizes the gc behavior to achieve minimal
                                          pause times 
          		  deterministic	optimizes the gc behavior to ensure extremely
                                          short pause times and limit the total number of
                                          those pauses within a prescribed window (this
                                          feature requires a valid license)
              -Xgc:[singlecon|gencon|singlepar|genpar]
                        used to set a static garbage collector
                        will override the -Xgcprio option
                            singlecon     use the single-spaced concurrent garbage
                                          collection algorithm (default in client mode)
                            gencon        use the generational concurrent 
                                          garbage collection algorithm
                            singlepar     use the single-spaced parallel 
                                          garbage collection algorithm
                            genpar        use the generational parallel 
                                          garbage collection algorithm
              -Xms<size>[g|G|m|M|k|K]
                        sets the initial Java heap size (ms)
                            server mode:  the default value is 25% of the amount 
          				of free physical memory in the system 
          				up to 64 MB with a minimum of 8 MB (default)
                            client mode:  the default value is 25% of the amount 
          				of free physical memory in the system 
          				up to 16 MB with a minimum of 8 MB
              -Xmx<size>[g|G|m|M|k|K]
          	      sets the maximum Java heap size (mx)
                            server mode:  the default value is the smallest of 75% of
                                 		physical memory and 1536 MB (default)
                            client mode: 	the default value is the smallest of 75% of
          				physical memory and 64 MB              
              -Xns<size>[g|G|m|M|k|K]
          	      sets the initial Java nursery size for generational collectors
                            server mode:  the default value is dynamic (throughput
                                          prio and genpar gc) or 10 MB per hardware
                                          thread (pausetime prio and gencon gc)
                            client mode:  the default value is 2 MB            
              -Xss<size>[g|G|m|M|k|K]
                        set initial stack size
              -Xpausetarget=<optimal_pause_time>[ms|s]
                        JRockit will optimize the pause time to the given target,
                        uses -Xgcprio:pausetime
                            ms            pause time specified in milliseconds (default)
                            s             pause time specified in seconds
              -Xnoclassgc
                        disable class garbage collection
              -Xdebug
                        enables debugging support in the VM
              -Xrun<library>	    
                        loads and runs a library
              -Xmanagement
                        enable the management agent
              -Xnoopt   
                        do not optimize code
              -Xstrictfp
                        always use strict floating point calculations
              -Xverify  
                        do full bytecode verification
              -Xnohup or -Xrs
                        JRockit will not process CTRL_LOGOFF_EVENT or SIGHUP events
              -Xverbose[:memory|load|jni|cpuinfo|codegen|opt|gcpause|gcreport]
                        Enables verbose output. These are only a few of the 
                        available log modules. For more information on log 
                        modules refer to the documentation. 
              -Xverboselog:<file>
                        logs verbose output to a file 
              -Xverbosetimestamp
                        adds a timestamp to the verbose printout
              -Xverbosedecorations:<decorations>
                        adds <decorations> to the verbose printout
              -Xcheck:jni       
          	      perform additional checks for JNI functions
          For more information on these options refer to the documentation.
          The -X options are non-standard and subject to change without notice.
          
          

           

          IBM JDK 6

          以下選項是非標準選項,可隨時更改,而不另行通知。
          
            -Xbootclasspath:<path>    將引導類路徑設置為 <path>
            -Xbootclasspath/p:<path>  將 <path> 附加在引導類路徑前面
            -Xbootclasspath/a:<path>  將 <path> 附加到引導類路徑后面
          
            -Xrun<library>[:options]  裝入本機代理程序庫
                                      (不推薦,贊成使用 -agentlib)
          
            -Xshareclasses[:options]  啟用類數據共享(使用幫助獲取詳細信息)
          
            -Xint           僅運行已解釋的(等同于 -Xnojit -Xnoaot)
            -Xnojit         禁用 JIT
            -Xnoaot         不運行預編譯代碼
            -Xquickstart    通過延遲優化來減少啟動時間
            -Xfuture        啟用最嚴格的檢查,預測未來的缺省值
          
            -verbose[:{class|gcterse|gc|dynload|sizes|stack|debug}]
          
            -Xtrace[:option,...]  控制跟蹤使用 -Xtrace:help 以獲取更多詳細信息
          
            -Xcheck[:option[:...]]  控制檢查使用 -Xcheck:help 以獲取更多詳細信息
          
          以下選項的參數以字節為單位。
          帶有后綴“k”(千)或“m”(兆)的值會進行相應的計算。
          
            -Xmca<x>        將 RAM 類段增量設置為 <x>
            -Xmco<x>        將 ROM 類段增量設置為 <x>
            -Xmn<x>         將初始/最大新空間大小設置為 <x>
            -Xmns<x>        將初始新空間大小設置為 <x>
            -Xmnx<x>        將最大新空間大小設置為 <x>
            -Xmo<x>         將初始/最大舊空間大小設置為 <x>
            -Xmos<x>        將初始舊空間大小設置為 <x>
            -Xmox<x>        將最大舊空間大小設置為 <x>
            -Xmoi<x>        將舊空間增量設置為 <x>
            -Xms<x>         將初始內存大小設置為 <x>
            -Xmx<x>         將內存最大大小設置為 <x>
            -Xmr<x>         將記住的集合大小設置為 <x>
            -Xmrx<x>        將記住的集合的最大大小設置為 <x>
            -Xmso<x>        將操作系統線程堆棧大小設置為 <x>
            -Xiss<x>        將初始 java 線程堆棧大小設置為 <x>
            -Xssi<x>        將 java 線程堆棧增量設置為 <x>
            -Xss<x>         將最大 java 線程堆棧大小設置為 <x>
            -Xscmx<x>       將新共享類高速緩存的大小設置為 <x>
            -Xscminaot<x>   將為 AOT 數據保留的最小共享類高速緩存空間設置為 <x>
            -Xscmaxaot<x>   將允許用于存儲 AOT 數據的最大共享類高速緩存空間設置為 <x>
            -Xmine<x>       將堆擴展的最小大小設置為 <x>
            -Xmaxe<x>       將堆擴展的最大大小設置為 <x>
          
          以下選項的參數以 0 至 1 的小數表示。
          值為 0.3 表示請求百分比為 30%
          
            -Xminf<x>       GC 之后自由堆的最小百分比
            -Xmaxf<x>       GC 之后自由堆的最大百分比
          
          以下選項的參數以小數表示。
          
            -Xgcthreads<x>                設置 GC 線程的數量
            -Xnoclassgc                   禁用動態類卸裝
            -Xclassgc                     啟用動態類卸裝
            -Xalwaysclassgc               啟用每個 GC 的動態類卸裝
            -Xnocompactexplicitgc         禁用系統 GC 的壓縮
            -Xcompactexplicitgc           啟用每個系統 GC 的壓縮
            -Xcompactgc                   啟用壓縮
            -Xnocompactgc                 禁用壓縮
            -Xlp                          啟用大頁面支持
            -Xrunjdwp:<options>           啟用調試,JDWP 標準選項
            -Xjni:<options>               設置 JNI 選項
          
          posted on 2012-03-01 16:43 BeanSoft 閱讀(7097) 評論(0)  編輯  收藏 所屬分類: JVM
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