支持启动时选择 JVM 进程列表;

支持观测详细的收集器GC暂停时间;

图表支持鼠标移动详细信息显示(时间和值);

支持 Hotspot JDK  8+版本下运行, 可检测 Hotspot JDK 1.5 ~ 14, 在 CMS, G1等收集器下检测通过;

中英双语显示.

此工具仅希望能有所帮助, 但不提供任何担保.

源码地址: https://github.com/beansoftapp/gcperf

原始项目: https://github.com/bitcharmer/gcperf

原始介绍: https://dzone.com/articles/visualvm-gcviewer-plugin

下载

gcperf.nbm 中文多语言版

gcperf_en.nbm 英文版

Java 8(VisualVM 1.0)适用

VisualVM 2.0适用

术语简单解释:

参考 JDK 源码: AdaptiveSizePolicy.Design.txt

活动区 liveSpace = baseFootprint + oldAlive + youngAlive 闲置区 freeSpace = promoSize + edenSize

重要说明: 此项目仅支持 OpenJDK 和 Hotspot, 通过使用 JVMStat API 来读取内置的 HotSpot 计数器. 因为某些原因, 新的并行GC (-XX:+UseParNewGC) 不再提供和旧的并行扫描收集器(-XX:+UseParallelGC)相同的计数器, 所以新版下只能看到 GC 暂停时间和已提升对比已存活两个图表 .

其它的GC算法能否显示暂未测试.

运行截图:

英文截图:

中文（内容有滞后）：http://www.oracle.com/technetwork/cn/middleware/ias/downloads/wls-main-091116-zhs.html

Oracle优秀英文博客：

• WebLogic Server 团队
• James Bayer
• Antony Reynolds
• Adam Bien
• Middleware Magic

• The Aquarium
• Jeff West
• Steve Button
• Markus Eisele

• Arun Gupta
• John Graves
• Bala Kothandaraman
• Simon Haslam

运行截图:

2010-09-10 WLSMonitor 1.1 beta

本免费版本的后续版本收费，WLS Monitor for WebLogic 9, 10, 11g 基于Web模式开发，使用Tomcat进行部署。更多信息请咨询站长。

http://cid-519b3f7aa2172030.office.live.com/self.aspx/Public/WebLogic/wlstat1.1.zip

下面列出了各个厂商的输出，可以看到IBM的帮助最详细而且是中文的，有意思。

另外JRockit还支持一个 -XX参数，其输出如下：

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的输出：

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

以下选项是非标准选项，可随时更改，而不另行通知。

  -Xbootclasspath:<path>    将引导类路径设置为 <path>
  -Xbootclasspath/p:<path>  将 <path> 附加在引导类路径前面
  -Xbootclasspath/a:<path>  将 <path> 附加到引导类路径后面

  -Xrun<library>[:options]  装入本机代理程序库
                            （不推荐，赞成使用 -agentlib）

  -Xshareclasses[:options]  启用类数据共享（使用帮助获取详细信息）

  -Xint           仅运行已解释的（等同于 -Xnojit -Xnoaot）
  -Xnojit         禁用 JIT
  -Xnoaot         不运行预编译代码
  -Xquickstart    通过延迟优化来减少启动时间
  -Xfuture        启用最严格的检查，预测未来的缺省值

  -verbose[:{class|gcterse|gc|dynload|sizes|stack|debug}]

  -Xtrace[:option,...]  控制跟踪使用 -Xtrace:help 以获取更多详细信息

  -Xcheck[:option[:...]]  控制检查使用 -Xcheck:help 以获取更多详细信息

以下选项的参数以字节为单位。
带有后缀“k”（千）或“m”（兆）的值会进行相应的计算。

  -Xmca<x>        将 RAM 类段增量设置为 <x>
  -Xmco<x>        将 ROM 类段增量设置为 <x>
  -Xmn<x>         将初始／最大新空间大小设置为 <x>
  -Xmns<x>        将初始新空间大小设置为 <x>
  -Xmnx<x>        将最大新空间大小设置为 <x>
  -Xmo<x>         将初始／最大旧空间大小设置为 <x>
  -Xmos<x>        将初始旧空间大小设置为 <x>
  -Xmox<x>        将最大旧空间大小设置为 <x>
  -Xmoi<x>        将旧空间增量设置为 <x>
  -Xms<x>         将初始内存大小设置为 <x>
  -Xmx<x>         将内存最大大小设置为 <x>
  -Xmr<x>         将记住的集合大小设置为 <x>
  -Xmrx<x>        将记住的集合的最大大小设置为 <x>
  -Xmso<x>        将操作系统线程堆栈大小设置为 <x>
  -Xiss<x>        将初始 java 线程堆栈大小设置为 <x>
  -Xssi<x>        将 java 线程堆栈增量设置为 <x>
  -Xss<x>         将最大 java 线程堆栈大小设置为 <x>
  -Xscmx<x>       将新共享类高速缓存的大小设置为 <x>
  -Xscminaot<x>   将为 AOT 数据保留的最小共享类高速缓存空间设置为 <x>
  -Xscmaxaot<x>   将允许用于存储 AOT 数据的最大共享类高速缓存空间设置为 <x>
  -Xmine<x>       将堆扩展的最小大小设置为 <x>
  -Xmaxe<x>       将堆扩展的最大大小设置为 <x>

以下选项的参数以 0 至 1 的小数表示。
值为 0.3 表示请求百分比为 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

以下选项的参数以小数表示。

  -Xgcthreads<x>                设置 GC 线程的数量
  -Xnoclassgc                   禁用动态类卸装
  -Xclassgc                     启用动态类卸装
  -Xalwaysclassgc               启用每个 GC 的动态类卸装
  -Xnocompactexplicitgc         禁用系统 GC 的压缩
  -Xcompactexplicitgc           启用每个系统 GC 的压缩
  -Xcompactgc                   启用压缩
  -Xnocompactgc                 禁用压缩
  -Xlp                          启用大页面支持
  -Xrunjdwp:<options>           启用调试，JDWP 标准选项
  -Xjni:<options>               设置 JNI 选项

声明:本站WebLogic文章将同步整理到老刘文库.

来源：http://allthingsmdw.blogspot.com/2012/02/multicast-vs-unicast-with-weblogic.html

THURSDAY, FEBRUARY 9, 2012

Multicast Vs. Unicast with WebLogic Clustering

WebLogic Clusters manage membership via messaging within its members. The members join/leave the cluster as well as update other members via messages to the entire cluster. There are two ways for cluster messaging in WLS - Multicast or Unicast. This post goes provides a brief overview of the cluster messaging and some general guidelines around using the different messaging options.
WLS Cluster
WebLogic clustering provides a homogeneous model for managing a set of server instances while providing scalability, load balancing and high availability to the services running within the member instances. For the end client, it appears like one single and uniform service with all the RASP (reliability, availability, scalability, performance) capabilities. Each cluster member is aware of other members and advertise each other services in addition to their own. Refer tohttp://docs.oracle.com/cd/E11035_01/wls100/cluster/failover.html for more details on replication and failover of clustered services.
Unicast & Multicast
Multicast is easier to explain over Unicast. Multicast is a broadcast UDP option for sending a packet/announcement over to a group that is listening on a specific multicast address and port over which the announcement is sent.There is a defined range for valid Multicast address (224.0.0.1 to 239.255.255.255). Everyone listening on the given address hears the announcement just like following a Twitter post. Some limitations with Multicast is the TTL (time to live) across machines/subnets/routers needs to be adjusted and the routers configured to retransmit the multicast packet across subnets. More details on the weblogic specific multicast configurations can be seen in my Exalogic and Multicast blog post.
Unicast is more of a point to point UDP option to send the packet to a specific member and not everyone. That way, unicast is more of a private conversation between two individuals while multicast is more of a shout to a group or room. Both are UDP based, so there can be losses unlike TCP that handles retransmissions on message loss. But Unicast can span across routers and does not have to worry about TTL without the everyone hearing the announcement. So, Network Admins in general prefer to go with Unicast over Multicast for these reasons.
WLS Cluster Configuration
When a cluster is created within a WLS Domain (either via wlst or config wizard or copy/update of existing domain), it is configured as using Unicast or Multicast messaging. As part of complete Cluster configuration, the multicast listen address and port should be specified if going with Multicast option. Also the managed servers should be targeted/added to the Cluster instance. There can be multiple clusters and any given managed server instance can only belong to atmost one cluster (or none). This will let the clustered managed servers (Admin Server should not be part of any cluster nor can cluster span domains) go with Unicast or Multicast when they are started. It should be noted that Multicast used to be the only option in WebLogic prior to 10.0 version while either Unicast or Multicast can be used from version 10 onwards.
Cluster Messaging
How does each member join the cluster and see or recognize others? At bootstrap time, the managed servers get their configuration via JMX MBeans from the Admin server (or from cached configurations if the Admin server was down) and recognize that they belong to a cluster and they have to go with Unicast or Multicast.
WLS Multicast Messaging
So, in a multicast messaging cluster, the managed servers start listening to the specified multicast address once it checks its configuration and knows it belongs to so and so cluster and has to use specified multicast address and port. Once it listens on the specified multicast address, it sends an announcement about its arrival to others via multicast - more like a shout-out. Other running clustered members of the same cluster who are already listening will respond back and add the new member to their list of known cluster members. The new member will also update its cluster list with other members. This process continues as new members get added. The membership gets renewed based on each member sending periodic announcements to other members proclaiming its liveliness. If a member goes down (shutdown or killed or not able to respond), then it wont be able to send its broadcasts and other members will drop it from the cluster list and re-add it when it comes back online. If a member is directly talking to another cluster member, just the direct socket connection is enough in establishing its membership with its connected member. Since multicast is a broadcast, just a single announcement is retain a instance's membership and let others continue to maintain it in their cluster list till its time to renew its membership. Its a mesh where every member can see every other member in the cluster.

WLS Unicast Messaging
With Unicast, WLS divides the cluster into a multiple groups, each having a max of 10 members. The division happens as the servers come up. Each of the server listens on their specified listen address and the other members can send/receive unicast packets over that listen address as every clustered member knows the configurations of other cluster members.
The oldest within the group is designated the group leader. The group leader communicates over Unicast to other members (over the specified member's listen address) within its group and adds/drops them based on them renewing their membership or not responding. The group leaders communicate amongst themselves. So, if there are 4 group leaders, each group having 10 servers, a membership announcement from server1 in group1 will be picked by GroupLeader1 of group1 and retransmitted to all other members within the group1 as well as to other three group leaders. The remaining group leaders will in-turn retransmit the membership information within their groups. This way, every change is picked up and retransmitted by the group leaders to within their group and to other groups via group leader to group leader communication. The group leaders remain the hub for each group while they themselves form a mesh with other group leaders.

Comparison between Unicast & Multicast

Multicast	Unicast
Only option in pre-10.0 versions of WLS, continues to exist in version 10+	Available from version 10 onwards
Requires configurations to Routers, TTL	No configuration required
Requires configuring the Multicast Listen Address and port	Just specify the listen address (can be Default Channel or use a Custom Network Channel for Cluster communication)
One announcement to join/maintain membership	one transmission to group leader has to be retransmitted to other group members (N) + to other group leaders (M) who then again retransmit to their group members resulting in (NxM) packets
Everyone sees everyone	Group Leaders have to do real heavy lifting of retransmitting every thing across its group and other group leaders and can get bogged down in just retransmitting
Can lead to big broadcasts through the entire subnet/LAN if there are frequent joins/drops of members or change in services (JNDI updates of bound services, frequent app deployments or members going out of sync)	Not a broadcast throughout the subnet/lan, but still more packets to be sent across as Group Leaders have to retransmit everything. Can consume bigger bandwidth

As listed in the table above, these would be my guidelines:

1. If the cluster is small and simple (under 20 members), go with Unicast. No configurations required and the group leaders wont be stretched retransmitting data.

2. If the Network configurations strictly prohibit multicast and members have to reside in different subnets and cluster sizes are still under or mid-20s, go with Unicast.

3. If its a real large cluster (over 20 members) and members can reside in the same subnet or even if they are not on same subnet but network router configurations can allow multicast, go with Multicast.

4. If over 50 members, change to network configurations to allow multicast and stick with Multicast.

5. Over 100 members, try to break up the domain into multiple separate domains and individual clusters for better administration and management even though Multicast option can handle such large domains. Or use custom scripts/wlst to manage and monitor individual members instead of relying on a single application (like console) to manage/monitor/handle all servers at the domain level.

The reason for recommending Multicast over Unicast for large clusters is due to the work load on the group leaders and retransmissions. The group leaders have to retransmit every member's packet within their group as well as to other group leaders (who again send to their group members) which can just lead to more and more work as the cluster grows bigger.
Another big reason is that WLS Multicast based messaging is quite mature and stable compared to Unicast which got only introduced with version 10. Also, with unicast, there can still be retransmits (as its not auto error correcting) and it can consume more bandwidth due to repeat retransmits by group leaders to others compared to one transmit for multicast.
Conclusions
I hope this article helps clarify the internal working of WLS Cluster membership around Unicast vs Multicast messaging while providing some guidance on the option to use based on requirements and constraints.

Posted by Sabha Parameswaran at 12:33 PM

文档:http://www.oracle.com/technetwork/middleware/weblogic/documentation/index.html

此次同时发布的还有Oracle Fusion Middleware 11g R1 (11.1.1.6.x),包含下列产品:

• Oracle WebLogic Server 11g R1 (10.3.6)
• Oracle SOA Suite 11g R1 (11.1.1.6.0)
• Oracle Business Process Management 11g R1 (11.1.1.6.0)
• Oracle Complex Event Processing 11g R1 (11.1.1.6.0)
• Oracle Service Bus 11g R1 (11.1.1.6.0)
• Oracle Enterprise Repository 11g R1 (11.1.1.6.0)
• Oracle Service Registry 11g R1 (11.1.1.6)
• Oracle Application Integration Architecture Foundation Pack 11g R1 (11.1.1.6.0)
• Oracle Data Integrator 11g R1 (11.1.1.6.0)
• Oracle WebCenter Portal 11g R1 (11.1.1.6.0)
  (previously known as Oracle WebCenter Suite)
• Oracle WebCenter Content 11g R1 (11.1.1.6.0)
  (previously known as Oracle Enterprise Content Management)
• Oracle Identity Management 11g R1 (11.1.1.6.0)
• Oracle Forms, Reports, Portal & Discoverer 11g R1 (11.1.1.6.0)
• Oracle Traffic Director 11g R1 (11.1.1.6)
• Oracle Repository Creation Utility 11g R1 (11.1.1.6.0)
• Oracle JDeveloper & Application Development Framework 11g R1 (11.1.1.6.0)

2010-08 微软网盘下载地址: MyEclipse 6 完整安装包下载

http://cid-519b3f7aa2172030.office.live.com/browse.aspx/Public/myeclipse 一共6个压缩包, 下载后解压缩即可安装运行, 不需要额外下载JDK, Eclipse等软件. 此软件仅供个人下载学习之用.

2. JDK 6 下载 http://java.sun.com/javase/downloads/widget/jdk6.jsp

3. Tomcat 6 下载 http://apache.deathculture.net/tomcat/tomcat-6/v6.0.28/bin/apache-tomcat-6.0.28.zip 或者进入页面 http://tomcat.apache.org/download-60.cgi

4. Oracle MySQL 5.5.16 绿色精简版 下载

下载地址: 3.12MB https://skydrive.live.com/redir.aspx?cid=519b3f7aa2172030&resid=519B3F7AA2172030!890

目前比较新的客户端, 个人用推荐免费的 Navicat 简装版(功能非常强大, 远超 MySQL Front 和 HeidiSQL, 美国宇航局NASA火星探测指定客户端), 下载地址 http://www.navicat.com/cn/download/download.html  企业用推荐HeidiSQL(开源免费, 英文) , 下载地址 http://heidisql.googlecode.com/files/HeidiSQL_5.1_Portable.zip 

5. 如何导入现有源代码的操作视频演示 eclipse_import_project.swf   762 KB 整理中

本软件具有Tomcat Manager应用的全部功能并增加了相关信息的监控功能，本人开发的中文语言包和使用说明文档收费，原英文版软件可从互联网下载。

最新版本：1.7b

许可：开源

操作系统：Java 跨平台，支持Tomcat 5, 6

下载地址及详细中文使用说明文档：发送邮件到beansoft@126.com联系购买。

运行截图：

一共约137篇文章，已经上传完毕，除个别文件因命名问题外上传失败，95%的文章已经可以直接浏览或打包下载了。WebLogic中文博客目前正在致力于新版本的通用Java中间件监控软件的研发中（单一软件支持Tomcat, Resin, JBoss, WebLogic, WebSphere，JVM运行状态监控等），因此近期将不会发表新的技术文章。如果您需要这些文章的word版本，请联系本人购买：beansoft@126.com 或者 QQ 9991483。

下面是所有WebLogic文章索引：

2009-11-01 配置 WebLogic Server 11g 集群单服务器版（Windows）.pdf
2009-11-06 WebLogic Server 11g节点管理器和Machine配置单机版（Windows）.pdf
2009-11-06 关于Spring和WebLogic版本兼容的一点小提示.pdf
2009-11-09 WebLogic 11g 如何修改 Console 的端口.pdf
2009-12 Weblogic 11 集群和节点管理器配置快速入门视频(单服务器版).pdf
2010-01-25 WebLogic各个版本对JDK和Spring的支持度.pdf
2010-03-23 JNDI 访问外部 WebLogic 11 数据源的操作步骤.pdf
2010-05-07 Oracle WebLogic Server 11g Rel 1 (10.3.3) 发布.pdf
2010-07-15 WLST on Weblogic 8.1下载地址(转).pdf
2010-08 WebLogic 9.2.4.0 发布.pdf
2010-08-13 WebLogic 11g 下载地址及 OEPE所有版本官方下载地址及所有版本文档(edoc)阅读下载地址.pdf
2010-08-16久违或遗忘的WebLogic Java工具.pdf
2010-08-19 简单的HelloWorld Portal 应用(for WLS 10).pdf
2010-08-20韩国wls监控 WLMonitor 2.5 beta 1 英文版下载.pdf
2010-08-31 Where to download file wlfullclient.jar.pdf
2010-09-09 WebLogic和JDK版本稳定度排行榜.pdf
2010-09-10 WebLogic静默卸载与安装[Slient Install and Uninstall].pdf
2010-11-26 WebLogic集群实现HTTP复制的简单步骤.pdf
2010-12-09 WebLogic Edoc中关于weblogic.Deployer的一点小问题.pdf
2011-02-27 如何修改weblogic默认线程池大小.pdf
2011-02-28 如何破解WebLogic管理密码.pdf
2011-03 WebLogic如何使用GridLink连接RAC数据库.pdf
2011-04-18 WebLogic散包部署禁用热加载.pdf
2011-05-07 WebLogic 10.3.5正式发布,提供下载.pdf
2011-05-22 基于JMS的Weblogic Server Webservice开发.pdf
2011-05-22基于JMS的Weblogic Server Webservice开发.pdf
2011-07-03 WebLogic 10.3.4支持JDK 7.pdf
2011-07-26借助 SAML 实现 WebLogic Server 9.2 单点登录相关文章.pdf
2011-07-28同时使用Oracle Exalogic Elastic Cloud和Exadata Database Machine的SquareTwo Financial公司[转].pdf
2011-07-31 3D立体展示 Oracle Exalogic Elastic Cloud X2-2.pdf
2011-08-03 关于WebLogic Windows 7版本.pdf
2011-08-04 ExaLogic EL X2-2 Edoc在线阅读及下载地址,安装视频.pdf
2011-08-12 WebLogic如何处理socket muxers[转].pdf
2011-08-23 Weblogic 10.3.5在64位Windows系统下的安装和配置.pdf
2011-08-24 WebLogic中的监视仪表盘(图文,视频).pdf
2011-08-26 WEBLOGIC JMS 点对点配置详解.pdf
2011-08-29使用WLST创建和删除DataSource.pdf
2011-08-30 WebLogic Express是免费的嘛 WebLogic是免费的嘛.pdf
2011-08-30 WLST快速创建单机Domain.pdf
2011-08-31 Solaris下如何安装WebLogic.pdf
2011-09-02使用代理插件时群集中的 HTTP 负载平衡问题[转].pdf
2011-09-04 AIX下WebLogic安装操作手册[转].pdf
2011-09-10调试基本WebLogic JDBC问题[转].pdf
2011-09-29 优化WebLogic 8服务器性能参数[转].pdf
2011-10 WebLogic Server Blog 内容收藏.pdf
2011-10-07 DomainHealth 1.0.0 发布.pdf
2011-10-10 使用WLST配置WebLogic密码策略.pdf
2011-10-19 WebLogic NodeManager 远程攻击漏洞补丁下载.pdf
2011-11 GlassFish 4.0 视频曝光,控制台酷似WebLogic.pdf
2011-11-09 WebLogic Web 应用映射到根目录.pdf
2011-11-28 如何抓取Thread Dump小结.pdf
2011-12 Oracle WebLogic Server 12c (12.1.1)正式发布.pdf
2011-12 WebLogic所有版本Edoc在线阅读及下载地址.pdf
2011-12 转载－weblogic 类加载机制.pdf
2011-12-02 Weblogic - Socket Muxers in Thread Dumps[转].pdf
2012-01-29各个版本WebLogic所支持的JDK及JavaEE版本.pdf
Accessing JMX for Oracle WebLogic 11g.pdf
BEA Weblogic Server宝典[中文图片版] [PDF].pdf
BEA Weblogic、Tuxedo 下载地址[转].pdf
BEA 产品文档[转].pdf
BEA-000337 错误解决[转].pdf
BEA-000402问题解决 but the maximum number of socket reader threads allowed by the configuration is.pdf
BEA公司被收购前所有版本软件支持的操作系统等配置信息列表.pdf
chaowang在甲骨文社区日的演讲教材下载.pdf
Debugging WebLogic Platform Internals.pdf
Enable IIOP and default user for the WebLogic server[转].pdf
Installing Oracle WebLogic Server and Creating a Domain [Linux].pdf
Jython相关文章收藏.pdf
Linux下Weblogic 11g jar格式安装包如何安装.pdf
Managing WebLogic servers with JConsole.pdf
Monitoring WebLogic 9 using JMX.pdf
Oracle Fusion Middleware支持的JDK等系统配置列表信息.pdf
Oracle WebLogic Integration.pdf
Oracle WebLogic Server 11g Monitor and Tune Performance课程介绍[转].pdf
Oracle WebLogic Server Enterprise Edition 报价.pdf
Oracle WebLogic Server Information Center[转].pdf
Oracle官方关于WebLogic服务有效期的文档.pdf
Performance and Tuning for Oracle WebLogic Server 11g[PDF] Download.pdf
Reason of java.lang.InternalError： erroneous handlers.pdf
startWebLogic.sh启动失败，提示Error initializing Embedded LDAP Server错误.pdf
WebLogic 10.3.4正式发布,提供下载,支持JSF 2.0, JPA 2.0和JAX-RS 1.1[图].pdf
WebLogic 10各个版本详细名称.pdf
Weblogic 11g 安装部署手册.pdf
WebLogic 11gR1 PS3所有BEA错误代码详细信息列表.pdf
WebLogic 8 debug flags.pdf
WebLogic 8 监控 wlstat 0.2, 方便监控weblogic的Sockets,jvm,jdbc,threads,session.pdf
WebLogic 8.1 FTP 下载地址(Windows版本).pdf
WebLogic 8.1.6 Windows 安装包下载.pdf
WebLogic 8.1.6的所有BEA错误代码索引.pdf
WebLogic 9 实现基于Oracle数据库的用户身份存储示例代码.pdf
Weblogic 9.2 部署 8.1 下运行的 EAR 出错的部分解决方法.pdf
WebLogic 9.2的所有BEA错误代码索引.pdf
Weblogic for aix操作手册.pdf
WebLogic JDBC 驱动的配置.pdf
WebLogic JSP Servlet 线程超时设置参数.pdf
WebLogic Portal服务器配置手册.pdf
WebLogic Server 10.3.4 Released – Key APIs of Java EE 6 and More[转].pdf
WebLogic Server 9 的 Web Service 编程之 JWS.pdf
WebLogic Server 9.2 集群配置单服务器版.pdf
WebLogic Server 9.2 集群配置单服务器版和多服务器版(PDF).pdf
WebLogic Server 9.2 集群配置多服务器版.pdf
WebLogic versioned deployment side-by-side[转].pdf
WebLogic 最新版本下载地址.pdf
weblogic.Admin[转].pdf
weblogic.security.internal.encryption.EncryptionServiceException： com.rsa.jsafe.JSAFE_PaddingException： Could not perform unpadding： invalid pad byte.pdf
weblogic.utils.classloaders.FilteringClassLoader所在包.pdf
WebLogic8.1打印详细的jdbc日志.pdf
Weblogic8.1集群中批量启动和关闭所有服务器的脚本[转].pdf
weblogic9 jdbc日志跟weblogic8的区别.pdf
WebLogic公司发展简史.pdf
WebLogic启用域之间的跨域安全 Enable Cross Domain Security between domains[转].pdf
WebLogic如何强制先加载WEB-INF／lib下的jar.pdf
WebLogic如何更换64位JDK[转].pdf
WebLogic密码恢复（一）[转].pdf
WebLogic密码恢复（二）[转].pdf
Weblogic的Machine,Server,Domain,Cluster的关系.pdf
WebLogic集群环境下如何访问EJB实现负载均衡.pdf
WLS10.3.0中，连接测试导致的connection pool shrinking(disabling)问题分析[转].pdf
WLST脚本获取ThreadDump[转].pdf
[WebLogic]dev2dev 2004 合订本下载.pdf
[转]EJB在Weblogic Server集群中的实现.pdf
[转]WebLogic 10.3.4 新功能：CAT - Classloader分析工具.pdf
[转]WebLogic ClassCastException 错误解析.pdf
[转]将WebLogic Server注册为Windows服务.pdf
【转】Weblogic挂起、宕机问题分析及优化.pdf
使用VisualVM远程监控WebLogic服务器JVM.pdf
使用WLST监控应用状态[转].pdf
使用WLST脚本列出JMS队列中的消息.pdf
删除WebLogic 10的缓存[转].pdf
原dev2dev的WebLogic General精华贴总.pdf
如何抓取Thread Dump小结.pdf
开发自定义的MBean来管理J2EE应用(第四部分)[转].pdf
想在WLST中运行本机命令.pdf
监控线程执行情况,耗光时自动输出thread内容[转].pdf
简单的Oracle WebLogic 11g安装部属手册(PDF).pdf
转 多机nodemanager测试小记&weblogic103.pdf
配置基于Coherence 的WebLogic Server会话管理[转].pdf
Weblogic 8.1 JNDI 教程PPT.swf
WebLogic Server 8.1 Performance Tuning Guide(调优中文文档).swf
对WebLogic Server JNDI 启用安全设置.swf
设置WebLogic集群(WebLogic 10 中文文档).swf

完整的Sun JDK JVM参数可参考官方文章:http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html

http://download.macromedia.com/pub/flashplayer/updaters/9/sa_flashplayer_9.exe

Windows Flash Player 9 Projector content debugger
http://download.macromedia.com/pub/flashplayer/updaters/9/sa_flashplayer_9_debug.exe

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作者: 刘长炯 BeanSoft@126.com 日期: 2011-11-28 本文环境: JDK 1.5/1.6, WebLogic 9.0 or later

当服务器挂起,崩溃或者性能底下时,就需要抓取服务器的线程堆栈(Thread Dump)用于后续的分析.

Thread dump提供了当前活动的线程的快照. 它提供了JVM中所有Java线程的栈跟踪信息

有很多方式可用于获取Thread Dump, 一些是操作系统特定的命令.

操作系统命令获取ThreadDump:

Windows:

1.      转向服务器的标准输出窗口并按下Control + Break组合键, 之后需要将线程堆栈复制到文件中

UNIX/ Linux

首先查找到服务器的进程号(process id), 然后获取堆栈.

1.      ps –ef  | grep java

2.      kill -3 <pid>

 注意一定要谨慎, 一步不慎就可能让服务器进程被杀死!

JVM 自带的工具获取线程堆栈:

JDK自带命令行工具获取PID并做ThreadDump:

1.         jps

2.         jstack <pid>

使用JVisualVM:

Threads 标签页àThreadDump按钮.

WebLogic 自带的获取 thread dump的工具:

1. webLogic.Admin 工具

a. 打开命令提示符, 通过运行<DOMAIN_HOME>/bin/setDomain.env设置相关类路径

b. 执行下面的命令

java weblogic.Admin -url t3://localhost:7001 -username weblogic -password weblogic1 THREAD_DUMP

注意: Thread Dump 会打印到标准输出, 如nohup日志或者进程窗口.

2. 使用 Admin Console

a. 登录 Admin Console , 点击对应的服务器

b. 点击Server à Monitoring àThreads

c. 点击: Dump Thread Stack 按钮

3. 使用WLST (WebLogic Scripting Tool)

connect(‘weblogic’,'weblogic1’,’t3://localhost:7001’)

cd(‘Servers’)

cd(‘AdminServer’)

threadDump()

disconnect()

exit()

注意: 线程堆栈将会保存在运行wlst的当前目录下.

4. 使用utils.ThreadDumper

用法:

C:\bea\wlserver_10.3\server\lib>java -cp weblogic.jar utils.ThreadDumper

Broadcast Thread dumps disabled: must specify weblogic.debug.dumpThreadAddr and

weblogic.debug.dumpThreadPort

Exception in thread "main" java.lang.IllegalArgumentException: Port out of range

:-1

        at java.net.DatagramPacket.setPort(Unknown Source)

        at java.net.DatagramPacket.<init>(Unknown Source)

        at java.net.DatagramPacket.<init>(Unknown Source)

        at utils.ThreadDumper.sendDumpMsg(ThreadDumper.java:124)

        at utils.ThreadDumper.main(ThreadDumper.java:145)

5. 如果服务器是作为Windows服务的方式运行, 请运行下列命令:

WL_HOME\bin\beasvc -dump -svcname:service-name

其它一些获取Thread Dump的工具有jrcmd, jrmc(JRockit VM自带) ,Samurai, JProfiler等, 还可通过JMX编程的方式获取, 如JDK自带示例代码:

$JAVA_HOME\demo\management\FullThreadDump

下载：BeijingAIR1.1.exe 3.58MB

当前版本: 3.44-1 (2011年02月28日) 约4MB

界面语言:中英文等多国语言

许可协议: GPL

支持平台: Windows 2000/XP/Vista/Seven,Debian/Ubuntu/Gentoo/Mandriva & RedHat/Fedora/FreeBSD,OSX (MacPorts)

下载地址: http://www.httrack.com/page/2/en/index.html

截图:

针对这个帖子内容略微做一声明：这个跟帖称本人为所谓的“自称开源技术爱好者”，网友们可以注意到本人的博客标题从来就是BeanSoft's Java Blog，本人主要关注Java项目开发相关领域的内容，如Java基础，SWT，AJAX，HTML，MyEclipse等，而不论是否开源，相信MyEclipse是商业软件没有多少人不知道吧，而本人的电子书《MyEclipse 6 Java 开发中文教程》则是网络上最受欢迎的Java教程之一，所以很遗憾本人并非开源技术爱好者，博客内容也仅为工作和学习的心得而已。本人博客曾长期位列BlogJava排名第一，因此原国内开源项目EasyJWeb（此项目目前基本已停滞）的开发者蔡世友（网名大峡）邀请本人推广其产品，在清华大学附近碰头，方才见过仅有的一面，此时也顺便碰见过从事原国内CowNew开源项目（此项目疑似已完全消失，目前已无法打开其官网http://www.cownew.com）的杨中科，这是我和此二人的唯一碰面，也可以勉强算是好友吧，本人对任何从事研发工作，乐于分享的技术人员都视为好友，至于此二人选择后续和传智播客合作，那是其个人自由，相信任何人都无权干涉。鉴于彼时本人博客排名第一，甚至于连传智播客的员工张孝祥也前来力邀本人授课并在本站挂载链接帮忙招生，很遗憾当发现传智播客不过是个小小的低端社会IT培训机构，学员水平参差不齐，只能听懂HelloWorld，深了他们听不懂，课程安排随时调换，师资力量薄弱，工资待遇差（兼职为600一天，全职月薪据张孝祥口头讲一般为底薪5K，其它部分上课了才有课时费据说200一天，周六也要去公司备课，不交保险和公积金，因最终未签合同，至于其它员工工资和转正工资到底多少，因为公司机密，本人不得而知，但这待遇对我毫无吸引力，我原来公司四险一金都有），本人考察情况后甚是担心留下会降低自己的技术水平，就在兼职3个月后果断离开了，如今在某知名外企工作。

更巧的是前一阵子碰到了当时带的一个学员，他亲口说当时大部分外地来京的学员，最后都走了，也没有从事IT相关的工作，更间接证实了低端IT培训所存在的一些问题。至于此人提到的学员抗议的问题，低端IT培训都不可能100%的人都满意，只要做到大部分人满意，这点本人还是有保证的，否则为何还要给我加课，这人说话这不是自相矛盾嘛？换言之如果文中认为本人讲课不好，那为何当时传智播客还一再让我授课，并安排多门课程如UML，Linux，Struts2，SCM，Linux等等？这难道不是培训机构误人子弟，不负责任的做法嘛？像课堂上讲课学生情绪很大，学生骂老师的事情，像张孝祥这样的老讲师也遭遇过吧？而且至今网上依然有人骂张孝祥，我看张孝祥依然在网上讲课录视频不是吗？至于说：“因为他讲课不好，传智播客网站上的教师队伍中从未出现过此人的姓名。”，这是因为本人并未与其进行长期合作的意愿，而且把兼职讲师列到教师队伍中，也于理不合。讲课期间，张孝祥一再想让我录课程视频发到网上做广告，但因为我的笔记本不兼容他所给的录屏软件Camtasia Studio的问题，没能如愿，这个兼职讲师录视频的事情，也是我从事低端社会IT培训和企业培训这么久来第一次遇到。但是本人还是给同学们录制了一部分现场课程的录像（BBFlashBack的.fbr格式）作为复习之用，这些视频至今仍在传智内部流传。至于“但传智领导想着他也经济情况窘迫”这样的说法，我不知道付出劳动获取报酬有什么错误，难道传智播客的讲课的员工也都是因为经济情况窘迫才去讲课挣钱的？也不知道到底是哪位“传智领导”说的这话？

再来看看文中所提：爱好写文档，文档写的很好，这些都是事实，也是成为高手的一个好办法，很遗憾本人就是一位Java高手。至于免费讲视频，本人从来就是乐于从事知识分享，谁都知道网上热心网友制作的免费视频很多，本人迁址后的新博客beansoft.biz依然有大量的文章和视频可供参考。曾经想从事IT培训也是事实，只不过对社会低端IT培训的乱象了解太少，所以才决定去试水。发现传智播客有个特点是要兼职老师自己做PPT教材，案例等文档（不知道他们为什么当时不提供教材），所以本人的出众文档能力独立编写了多部BeanSoft本人保有版权的文档如《SCM项目手把手开发文档》，《Struts 2 PPT》，《Linux讲义》，《UML》，《SCM、DRP项目开发》等。在这里给兼职讲师提个醒，这些自己研发的原创教材，千万不要随便给学生或者其它第三人，否则你就等着盗版到网上到处都下载吧，典型案例如本人《SCM项目手把手开发文档》，就被冠以传智播客前缀在网上四处都能见到下载，当时张孝祥说把作者去了可以突出公司形象，但因为我是兼职，因此这种做法对作者本人来说没有任何好处，很遗憾当时本人未能深刻意识到这一点。就有可能至于基本功这个，个人不好自己评价过高，不过本人目前从事中间件服务器研发工作，自认还是不低的。

再来说说我对从事培训工作的CSDN旗下传智播客员工张孝祥的了解，我从2003年毕业起，一直从事Java相关的项目研发和管理，也从事过企业的内部培训，直到2006年，才听说有个岁数不小的张孝祥和孙鑫，马士兵，李兴华等人一样，录了很多Java的入门学习视频，这些视频听起来湖北口音比较重，讲的也比较中规中矩些，不是很生动，虽然内容据说有些深度。后来看其个人公开的简历也就从事过六年项目研发，其中使用Java进行的项目看起来似乎只有一年时间，参考贴吧原文：

http://baike.baidu.com/view/7440.htm#sub5120082

之后据业内人士讲其曾在国信蓝点做培训讲师，至于讲课情况究竟如何不得而知，目前CSDN还有帖子评论他讲课不备课，讲课不系统，不过时间久远，已无从考证其真实情况：

http://topic.csdn.net/t/20061102/19/5129142.html

。这一特点至少在2008年还存在，就是喜欢在本人讲课的时候，夺过话筒，大讲特讲其所认为的原理和心得，以至于被学生多次抗议后才罢手，本人当时发给学员的现场课程实录视频上，就有这样的真实记录。于2006年CSDN投资开办社会IT低端培训机构传智播客，张孝祥则作为一位员工入职其中从事培训相关工作。后来他邀请本人前去从事兼职培训，在时间不长的接触中，也发现了他在Java项目开发上的欠缺，所以一再力邀本人为其课程开发演示项目SCM。至于他到了2009年才学会Struts并录了视频这些，也间接证实了作为曾经的程序员，岁数太大，学不动真是个自然规律。

张孝祥此人品行如何，我们不能作主观任何评论，物以类聚、人以群分，这还要看他有没有朋友说起，他自称“中国Java培训第一人”、软件编程语言培训师，然而，似乎却与同样使用编程语言从事研发工作的郝培强先生、老赵和本人等都合不到一起去，而和从事Java培训的讲师马士兵、孙鑫和李兴华等人也合不来，甚至于和同行青鸟、达内、蓝点等培训机构也似乎不甚友好。

我本想对传智播客继续保持沉默，不把本人与传智播客的这些恩恩怨怨告知于众，因为这样对我自身的影响也不好。但是，此人竟然如此挑衅，我们就不能不给大家一个交待了。

最后一起来看看这篇匿名用户发的帖子，本人业已截图保存做了相关备份:

 http://tieba.baidu.com/f?kz=1113350066 地址为百度贴吧传智播客吧：

原文: http://www.tagtraum.com/gcviewer-vmflags.html

VMFlags

When it comes to garbage collector and memory flags VMs from different vendors differ somewhat. Most flags aren't even properly documented by the usage printout of the VM themselves. This page tries to shine some light on what garbage collection related flags there are and what they are good for. It covers several Sun and IBM JVMs

Sun JVMs

Disclaimer: Please note that the data presented in this document has been gathered from several publicly available sources. It is a conscious selection of available VM parameters and even though we tried to check most of the facts presented this document may contain errors.

Choosing a VM

-server

Instructs the VM to use the server HotSpot VM. This also implies that default heap sizes and permanent generation sizes are different.
Under 1.5 this option is the default option, if the machine is a server-class machine.
Supported by: 1.3, 1.4, 1.5

-client

Instructs the VM to use the client HotSpot VM. This also implies that default heap sizes and permanent generation sizes are different.
Supported by: 1.3, 1.4, 1.5

Printing Information about GC

-verbose:gc

Prints out information about garbage collections to standard out. To print the same information to a file, use -Xloggc:<file>
Example:
[GC 325407K->83000K(776768K), 0.2300771 secs]
[GC 325816K->83372K(776768K), 0.2454258 secs]
[Full GC 267628K->83769K(776768K), 1.8479984 secs]
See -Xloggc
Supported by: 1.3, 1.4, 1.5

-Xloggc:<file>

Prints information about garbage collections to the specified file.
In conjunction with -XX:+PrintGCDetails this is the best setting for the free GCViewer.
Supported by: 1.4, 1.5

-XX:+PrintGCDetails

Instructs the VM to be more verbose when printing out garbage collecion data. Specifically it does not only tell you that there was a collection, but also what impact it had on the different generations.
This flag is very useful when tuning generation sizes.
In conjunction with -Xloggc this is the best setting for the free GCViewer.
Example:
2.459: [GC 2.459: [DefNew: 3967K->0K(4032K), 0.0141600 secs] 8559K->7454K(16320K), 0.0143588 secs]
Supported by: 1.4, 1.5

-XX:+PrintGCApplicationStoppedTime

Instructs the VM to print out the length of actual collection pauses.
This flag is useful when tuning concurrent collectors.
Example:
Total time for which application threads were stopped: 0.0468229 seconds
Supported by: 1.4, 1.5

-XX:+PrintGCApplicationConcurrentTime

Instructs the VM to print out the amount of time the applications runs between collection pauses.
This flag is useful when tuning concurrent collectors.
Example:
Application time: 0.5291524 seconds
Supported by: 1.4, 1.5

-XX:+PrintGCTimeStamps

Ensures that timestamps relative to the start of the application are printed in the GC log.
Supported by: 1.4, 1.5

-XX:+PrintTenuringDistribution

Prints details about the tenuring distribution to standard out. It can be used to show this threshold and the ages of objects in the new generation. It is also useful for observing the lifetime distribution of an application.
Example:
5.350: [GC Desired survivor size 32768 bytes, new threshold 1 (max 31)
- age 1: 57984 bytes, 57984 total
- age 2: 7552 bytes, 65536 total
756K->455K(1984K), 0.0097436 secs]
Supported by: 1.3, 1.4, 1.5

Sizing Heap and Generations

-Xmx<value>

Overall maximum heap size. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xmx256m sets the maximum heap size to 256mb

Supported by: 1.3, 1.4, 1.5

-Xms<value>

Minimum heap size. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xms256m sets the minimum heap size to 256mb

Supported by: 1.3, 1.4, 1.5

-Xmn<value>

Sets the size of the young generation. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xmn64m sets the young generation size to 64mb

Supported by: 1.4, 1.5

-XX:MinHeapFreeRatio=<minimumInPercent>

Sets the minimal percentage of free heap memory that has to be available after a collection. This parameter can be used to influence when the VM is going to request more memory.
Example:

-XX:MinHeapFreeRatio=70

See -XX:MaxHeapFreeRatio
Supported by: 1.3, 1.4, 1.5

-XX:MaxHeapFreeRatio=<maximumInPercent>

Sets the maximal percentage of free heap memory that must at most be available after a collection. This parameter can be used to influence when the VM is going to lower its footprint. In other words it can shrink the heap and therefore memory consumption.
Example:

-XX:MaxHeapFreeRatio=20

See -XX:MinHeapFreeRatio
Supported by: 1.3, 1.4, 1.5

-XX:NewRatio=<ratio>

Sets the ratio between young and old generation.
Example:

-XX:NewRatio=3 means that the ratio between the young and old

generation is 1:3; in other words, the combined size of

eden and the survivor spaces will be one fourth of the

heap.

See -XX:NewSize and -XX:MaxNewSize
Supported by: 1.3, 1.4, 1.5

-XX:NewSize=<value>

Sets minimum size of the young generation.
Example:

-XX:NewSize=64m sets the minimum size of the young

generation to 64mb

See -XX:NewRatio and -XX:MaxNewSize
Supported by: 1.3, 1.4, 1.5

-XX:MaxNewSize=<value>

Sets maximum size of the young generation.
Example:

-XX:NewSize=64m sets the maximum size of the young

generation to 64mb

See -XX:NewRatio and -XX:NewSize
Supported by: 1.3, 1.4, 1.5

-XX:SurvivorRatio=<ratio>

Sets size of the survivor spaces in relation to eden.
Example:

-XX:SurvivorRatio=6 sets the ratio between each survivor space

and eden to be 1:6; in other words, each survivor space

will be one eighth of the young generation (not one seventh,

because there are two survivor spaces).

Supported by: 1.3, 1.4, 1.5

-XX:PermSize=<value>

Sets the initial size of the permanent generation (where classes etc. are stored). This can be useful for application servers using many EJBs and JSPs.
Example:

-XX:PermSize=64m

See -XX:MaxPermSize
Supported by: 1.3, 1.4, 1.5

-XX:MaxPermSize=<value>

Sets the maximum size of the permanent generation (where classes etc. are stored). This can be useful for application servers using many EJBs and JSPs.
Example:

-XX:MaxPermSize=64m

See -XX:PermSize
Supported by: 1.3, 1.4, 1.5

Choosing and Configuring a Collector

-XX:+UseParallelGC

Use parallel garbage collection. This collector is also referred to as the throughput collector. It uses a parallel version of the young generation collector. The old (tenured) generation is still cleaned with the default collector.
Under 1.5 this option is the default option, if the machine is a server-class machine.
This option can not be used in conjunction with -XX:+UseConcMarkSweepGC .
Supported by: 1.4.1, 1.5

-XX:+UseParallelOldGC

Use the parallel old generation collector. Certain phases of an old generation collection can be performed in parallel, speeding up an old generation collection.
This option automatically enables -XX:+UseParallelGC .
Supported by: 1.5.0.6

-XX:ParallelGCThreads=<number>

Specifies the number of threads used in parallel garbage collection when -XX:+UseParallelGC is set. By default a system with N CPUs uses N garbage collection threads.
Example:

-XX:ParallelGCThreads=4

Supported by: 1.4.1, 1.5

-XX:MaxGCPauseMillis=<ms>

Instructs the VM to try to keep garbage collection pauses shorter than the specified value in ms.
This option applies in conjunction with -XX:+UseParallelGC and has higher priority than -XX:GCTimeRatio .
Example:

-XX:MaxGCPauseMillis=10

Supported by: 1.5

-XX:GCTimeRatio=<ratio>

Sets a throughput goal for the VM. The ratio of garbage collection time to application time is1/(1+<ratio>).
This option applies in conjunction with -XX:+UseParallelGC and has lower priority than -XX:MaxGCPauseMillis .
Example:

-XX:GCTimeRatio=19 sets a goal of 5% of the total time for

garbage collection.

Supported by: 1.5

-XX:+UseAdaptiveSizePolicy

Instructs the VM to keep track of some statistics and resize both the young and the old (tenured) generation based on the collected data.
This feature is on by default when the option -XX:+UseParallelGC is used.
Supported by: 1.4.1, 1.5

-XX:+AggressiveHeap

Instructs the JVM to push memory use to the limit. It inspects the machine resources (size of memory and number of processors) and attempts to set various parameters to be optimal for long-running, memory allocation-intensive jobs. This option is recommended for dedicated server machines.
The physical memory on the machines must be at least 256MB before AggressiveHeap can be used.
Beginning with JVM 1.3.1_02 some GC activity is done in parallel.
Beginning with JVM 1.4 this option implies -XX:+UseParallelGC and -XX:+UseAdaptiveSizePolicy .
Supported by: 1.3, 1.4, 1.5

-XX:+UseConcMarkSweepGC

Use concurrent garbage collection. This collector is also referred to as the concurrent low pause collector. It collects garbage in the old (tenured) generation concurrently to executing the application.
Note that this option can not be used in conjunction with -XX:+UseParallelGC . Instead you may combine it with -XX:+UseParNewGC
Supported by: 1.4.1, 1.5

-XX:+CMSParallelRemarkEnabled

If the -XX:+UseParNewGC option is in use the remark pauses may be decreased with the -XX:+CMSParallelRemarkEnabled option.
Supported by: 1.4.1, 1.5

-XX:+UseParNewGC

Instructs the VM to use a parallel collector for the young generation. This option should be used in conjunction with -XX:+UseConcMarkSweepGC .
Supported by: 1.4.1, 1.5

-XX:+UseTrainGC

Activates the train garbage collector. Note that development for this collector has been stopped since 1.4.2.
See -Xincgc
Supported by: 1.3, 1.4, 1.5

-Xincgc

Activates the incremental (also called train) garbage collector.
See -XX:+UseTrainGC
Supported by: 1.3, 1.4, 1.5

Miscellaneous Settings

-Xss<value>

Sets the size of the stack. In a server system with many threads lowering the stack size may be advantageous to reduce footprint. If the stack is too small, you will start seeingStackOverflowErrors.
You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xss128k sets the stack size to 128kb

Supported by: 1.3, 1.4, 1.5

-XX:+DisableExplicitGC

Disables calls to java.lang.System.gc().

-XX:SoftRefLRUPolicyMSPerMB=<ms per mb>

Sets the rate at which the VM clears soft references. The rate is expressed in ms per free mb of heap. For the server VM free heap means potentially free heap using the maximum heap size as set with -Xmx in the calculation. For the client VM the free heap is calculated using the actual current heap size.
Example:

-XX:SoftRefLRUPolicyMSPerMB=1000 instructs the VM to allow

softly reachable objects to remain alive for 1s per free mb

Supported by: 1.3.1, 1.4, 1.5

Server-Class Machine

Java 5.0 (1.5) defines a class of machines referred to as server-class machines. These are machines that have 2 or more physical processors and 2 or more gb of physical memory. On server-class machines the Sun JVM starts with altered default settings. These are:

-server -XX:+UseParallelGC

Additionally the initial heap size ( -Xms ) is set to 1/64 of the physical memory, up to 1gb. The maximum heap size ( -Xmx ) is set to 1/4 of the physical memory, up to 1gb.

Note that on server-class 32bit-Windows systems the VM will nevertheless start with the classic client settings, as most 32bit-Windows Java applications are not server applications.

IBM JVMs

Disclaimer: Please note that the data presented in this document has been gathered from several publicly available sources. It is a conscious selection of available VM parameters and even though we tried to check most of the facts presented this document may contain errors. Also note that the semantics of some of these parameters are different when used with IBM's resettable JVM for the z/OS platform.

Printing Information about GC

-verbose:gc

Prints out information about garbage collections to standard out.
See -Xverbosegclog
Supported by: 1.3.1, 1.4.1, 1.4.2

-Xverbosegclog:<path to file><filename[,X,Y]>

Prints out information about garbage collections to a file. If the integers X and Y are specified, the output is redirected to X files each containing output from Y GC cycles.
See -verbose:gc
Supported by: 1.4.1, 1.4.2

Sizing Heap and Generations

-Xmx<value>

Overall maximum heap size. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xmx256m sets the maximum heap size to 256mb

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xms<value>

Overall minimum heap size. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xmx256m sets the minimum heap size to 256mb

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xinitsh<value>

Sets the initial size of the system heap. Classes in this heap exist for the lifetime of the JVM. The system heap is never subjected to garbage collection. The maximum size of the system heap is unbounded. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xinitsh256m sets the minimum system heap size to 256mb

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xmaxf<value>

This is a floating point number between 0 and 1, which specifies the maximum percentage of free space in the heap. The default is 0.6, or 60%. When this value is set to 0, heap contraction is a constant activity. With a value of 1, the heap never contracts. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xmaxf0.6 specifies that the heap will be contracted if more

then 60% of the heap are unused.

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xminf<value>

This is a floating point number between 0 and 1, which specifies the minimum percentage of free space in the heap. The default is 0.3, or 30%. The heap grows if the free space is below the specified amount. You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xminf0.3 specifies that the heap will be grown if less

then 30% of the heap are unused.

Supported by: 1.3.1, 1.4.1, 1.4.2

Choosing and Configuring a Collector

-Xgcpolicy:<optthruput|optavgpause|subpool>

Note that the subpool option was introduced in Version 1.4.1 Service Refresh 1 for AIX only.
Setting gcpolicy to optthruput disables concurrent mark. If you do not have pause time problems (as seen by erratic application response times or by analysis of the verbose GC output), you should get the best throughput with this option. optthruput is the default setting.
Setting gcpolicy to optavgpause enables concurrent mark with its default values. If you are having problems with erratic application response times that are caused by normal garbage collections, you can remove those problems at the cost of some throughput when running with theoptavgpause option.
Setting gcpolicy to subpool enables improved object allocation that aims to achieve better performance in allocating objects on the heap. This setting might provide additional throughput optimization because it can improve the efficiency of object allocation and reduce lock contention on large SMP systems. Concurrent mark is disabled when this policy is enabled.
Supported by: 1.3.1, 1.4.1, 1.4.2

-Xgcthreads<n>

Sets the total number of threads that are used for garbage collection. On a system with n processors, the default setting is n.
Supported by: 1.3.1, 1.4.1, 1.4.2

-Xcompactgc

Compacts the heap every garbage collection cycle. The default is false (that is, the heap is not compacted). This is not recommended.
Supported by: 1.3.1, 1.4.1, 1.4.2

-Xnocompactgc

Never compact the heap. Default is false.
Supported by: 1.3.1, 1.4.1, 1.4.2

-Xnoclassgc

Disables class garbage collection.
Supported by: 1.3.1, 1.4.1, 1.4.2

Miscellaneous Settings

-Xss<value>

Sets maximum native stack size for any thread.
You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xss128k sets the stack size to 128kb

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xoss<value>

Sets maximum Java stack size for any thread.
You may use k, m and g for kilobyte, megabyte and gigabyte.
Example:

-Xoss128k sets the stack size to 128kb

Supported by: 1.3.1, 1.4.1, 1.4.2

-Xcompactexplicitgc

Runs full compaction each time java.lang.System.gc() is called. Its default behavior with ajava.lang.System.gc() call is to perform a compaction only if an allocation failure triggered a garbage collection since the last java.lang.System.gc() call.
Supported by: 1.4.1, 1.4.2

-Xnocompactexplicitgc

Never runs compaction when java.lang.System.gc() is called. Its default behavior with ajava.lang.System.gc() call is to perform a compaction only if an allocation failure triggered a garbage collection since the last java.lang.System.gc() call.
Supported by: 1.4.1, 1.4.2

-Xdisableexplicitgc

Converts Java application calls to java.lang.System.gc() into no-ops.
Supported by: 1.4.1, 1.4.2

[原]传智播客还是传诈播客？

obug门肖老湿的事件刚平息没几天，传智播客的张孝祥老湿又蹦出来了，很搞笑啊。事情的起因是：张老湿为了学生能够找到一份月薪7K的工作，帮学生做面试题，还美其名曰：这跟新东方和老罗研究考题没什么区别。详细信息看这里。老湿，拜托不要这么弱智好不好——研究考题跟老湿直接帮学生考试性质完全不一样，好不？还有人说张老湿这是分享知识——拜托各位脑残：软件行业的大牛们很多人都很喜欢分享知识，但绝对不会去替人答考试题。黑客精神是乐于分享，但不是乐于替考当枪手。
很久以来，我对于IT培训机构培养出来的学生有偏见——现在也如此。在我眼里，IT培训机构除了欺诈，什么都不教。这种观点很极端，但如果说给了这种机构出来的应聘者机会，那就是剥夺了诚信的应聘者的机会，还容易导致企业招聘成本的增高，那这样对谁都不公平。
我承认这些培训机构里面还是有些真正的人才的。但首先，培训机构出来的学生基数比较大，人才比例比较小；其次，能够忍受培训机构的欺诈行为，即便是人才，也会有些耳濡目染。圆滑奸诈的企业主和挑剔的面试官会为了一个小比例而去增加自己的成本和工作量吗？我想，换作我，我为什么不选择相对安全而又工作量小的方式，选择诚信度看起来高一点的应聘者呢？
在此我本不想从道德角度来说什么。谁没有阴暗的一面呢？谁没有干过缺德事呢？但张老湿先是把自己的道德提升到一个高度，然后自嘲了下“在别人的影响下也闯过红灯”，这就没意思了——我管你闯不闯红灯，你闯了，道德不会惩罚你，但死神可能会把你找去给他创办IT培训机构。你道德再高尚，你也无法否定你曾经犯下的错误。中国人就这么搞笑，总喜欢从道德方面说事。
张老湿跟肖老湿有一个共同点，就是逻辑比较混乱——可能是打太极打多了——你跟他讲错误，他跟你讲道德；你跟他将道德，他跟你讲责任……我就不明白了，你丫认个错能死？伟人毛主席都会犯错，难道张老湿你更伟大？
CSDN上脑残居多，这就是我从来不去的原因——去多了，难免会让自己也变成脑残的。

直接导入项目到Eclipse中, 运行src下唯一的一个.java文件即可,使用内嵌HSQLDB作为工作流数据的存储引擎,纯Java项目不依赖Web容器.

参考视频: http://family168.googlecode.com/files/%E7%AC%AC%E4%B8%80%E8%AF%BE.rar

jBPM相关学习视频: http://code.google.com/p/family168/downloads/list

下一步的目标就是学习Oracle SOA Suite中的 OSB, BPEL 和 BPM.

下载地址, 选择GDI模式并缩小FPS可得到小体积视频.

BB FlashBack Express

Version: 3.0.0.1905
Released: 07 Jul 2011
Size: 10.8 Mb
Runs On: Windows 7, Vista, XP, 2003, 2000 (32 and 64 bit versions)

http://tieba.baidu.com/i/171167167?st_mod=pb&fr=tb0_forum&st_type=uname

这位不成熟的发帖哥, 从5月到7月, 一直重复的在各个贴吧发表同一主题的帖子, 还自己顶自己, 甚至节假日也不休息, 您真的太辛苦了!

首先, 学员自身的问题. 严格讲, 程序员这一职业是需要思考和创造的, 对基础的英语和理解能力也有很高要求, 并不是靠背熟几段代码和API就能胜任的, 因此对综合实力要求很高. 但培训机构抛弃道德底线, 直接将其所谓的入学面试题公之于众, 只要交钱就可以上培训, 甚至公然鼓吹高中生也能干IT, 导致大批企图投机者自愿受骗, 参加培训, 但终归出来的还是次品, 不符合企业的长远用人要求, 害人害己, 多数人长远发展缺乏后劲. 如今, 北大青鸟, 传智播客等低端软件培训机构，不断遭到一些用人单位封杀其学员, 简历中直接过滤掉, 这也是不得已的选择. 参考:为什么我们招聘的时候绝不要传智播客的学生[转]老赵-为什么我要反对北大青鸟

其次, 低端软件培训公司弄虚作假, 推波助澜. 第一个问题是师资, 明明是普通程序员, 楞给包装成"架构师". 有的机构则列举一大批子虚乌有的师资阵容. 招生后, 已经赚到了钱. 但是要想赚更多的钱, 就要提高就业率, 来招更多的学生. 因此, 如何帮助学员修改简历, 伪造工作经验, 就成了重头戏. 这也导致众多用人单位封杀其学员. 因为这浪费的是用人单位的金钱和时间, 增加了招人的成本和项目开发过程中的风险. 至于有人甚至公然或者暗地里替学员做笔试题, 那就更加的恶劣. 这些培训机构实际上已经成为整个IT业发展的障碍之一.

最后, 低端软件培训, 之所以低端, 是因为他们培训的都是一些互联网上唾手可得的技术(如Spring, Struts, Hibernate, JBPM, Tomcat, Lucence, .NET, PHP, Java, AJAX, MySQL, Ruby, Android), 以开源免费以及官方公开的文档为主, 这些东西本来到处都有资料可看, 只需要动动手点击搜索, 然后下载, 实验, 就可以, 至于相关的书籍, 书店里更是又便宜又多. 但是为了招生, 稻草吹成金条, 拼命鼓吹自己培训的内容是如何如何高端, 就十分的可笑. 既然这些东西大家都会, 学员又有什么核心竞争力可言? 增删改查复制粘贴嘛? 所以不要指望能学到什么能保月薪10K+的高端技术, 用人单位自然也不可能学员开出昂贵的工资, 因为, 你们不是不可替代. 有这么多学费的投入(Java 约1万元左右, 其它约4K左右), 完全可以买一个笔记本电脑+N本书籍, 在大学里自学完成这些技术的积累(大三到大四两年多时间, 足够了). 如果你没有这种学习意识和自学能力, 不转行的话恐怕永远只能做底层小码农.

作为小结, 再讲下高端软件培训, 这些培训一般由Apple,Oracle,IBM,MS,Adobe等上游企业面向最终客户, 一般以产品和技能培训为主, 以实现双赢为目的, 并不以就业为导向, 所以相对而言, 高端软件培训是很入流的职业.

2005年时, 本人接触到几个从达内培训毕业的学员, 工资约为6K. 这几个人的照片到现在还在达内培训的就业明星宣传板上, 这也是我第一次了解到了达内培训. 简言之, 2005年之前的培训, 因为IT形势较好, 学员素质普遍较高, 都是大中专以上学历, 还是有不少找到了6K,7K,8K的工作的, 例如就业到IBM等外企, 底薪就是8K.

到了2007年时, 一大批小培训机构纷纷成立. 此时, 僧多粥少,  北京已经很难招到学生了, 大批招收外地或高中毕业生来参加培训, 毕业后的学员薪水, 已经降低到了约3.5K.

到了2008年时, 本人在多家小培训机构现场了解到, 因为经济危机原因, 月薪2500一大把, 甚至压根找不到工作. 这是目前已知形势最差的一年, 但是奇怪的是, 众多机构依然标榜就业平均薪水4K, 不知道这些数据又是从何而来.

到了2009年时, 形势依然不佳, 但就业率稍有好转. 不过不要忘记, 2009年房价增涨一倍达到3W/平, 房租已经增长很多, 生活成本大幅度提升.

到了2010年, 房租暴涨, 搜搜新闻就有. 新闻上介绍说众多学生降低期望值, 甚至出现"中国大学生就业报告：英语计算机法学找活最难"(参考 http://learning.sohu.com/20100603/n272534767.shtml), 在这种情况下, 众多低端培训招生出现危机, 为此, 不惜进一步造假, 开始鼓吹只要学了最新的XX课程, 就业薪水马上就是7K,8K.

笔者也对已就业培训生的后续发展进行了跟踪调查, 和大多数大学毕业生一样, 超过50%的人转去其它行业 (因为学不会或者没兴趣), 另一小部分人在月薪逐步涨至税前6K,7K以上后, 失去发展动力, 而大部分人则涨至4K后, 没了下文. 不要忘了北京的生活成本甚高,  6K的税后工资约为4700元, 房租一小间在1200元以上, 一个月吃饭加上交通, 就算最小值一天30, 那么一个月也得1000, 到底能留下几个钱, 相信这不是什么难算的帐. 在这种情况下, 根本谈不上娶妻生子, 买房? 那是做梦!

So why is it? 原因当然是众多, 然而其中一个最可能的原因是自学能力差, 看不懂英文资料(否则也不用去上培训了), 导致后续发展乏力. 大形势来说, 目前IT行业能吸收的程序员有限, 不如工厂能吸收的多, 因此导致供大于求, 这时要加薪自然是相当的困难.

2011年, 由于泡沫趋势明显, 部分大的互联网公司对程序员需求旺盛, 然而很遗憾的就是他们最需要的不是Java程序员, 而是PHP或者JavaScript,CSS高手. 详情参考各门户网站招聘主页即可.

根据新闻统计, 计算机业已连续三年失业严重!

在2009年CSDN已经发表了一篇新闻:  河北大学生就业报告:计算机专业毕业生失业最严重 http://news.csdn.net/a/20091027/214360.html 其中提到:

原为热门专业的计算机科学与技术、英语、国际经济与贸易、法学、工商管理连续两年失业严重。

下为转载: http://www.chinanews.com.cn/edu/news/2010/06-03/2320032.shtml

来源：中国新闻网

2010年06月03日04:27

转载注: 盲目参加所谓的包就业 Java 培训, 需谨慎!　现在就业形势确实不容乐观,　这不是广告和托们能改变的!

26日，由麦可思研究院(MyCOS Institute)撰写的《2009年河北省大学毕业生就业报告》完成。记者从报告中获悉，原为热门专业的计算机科学与技术、英语、国际经济与贸易、法学、工商管理连续两年失业严重。
(博讯 boxun.com)

5专业连续两年失业严重　
麦可思调查的河北省2008届本科各专业大类中，工学毕业半年后就业率最高，为90%；农学(72%)相对较低，理学(86%)、经济学 (84%)、医学(81%)和法学(80%)也均低于河北省(87%)和全国的本科毕业生毕业半年后平均就业率(88%)。麦可思调查的河北省2008届高职高专专业大类中，轻纺食品大类毕业半年后就业率最高，为90%；医药卫生大类毕业半年后就业率最低，仅为69%，远低于我省2008届高职高专毕业生的半年后平均就业率(82%)。
河北省2008届本科毕业生毕业半年后失业量最多的10个专业占了本科失业量的36.2%，其中有5个专业同时也是2007届失业最多的专业：计算机科学与技术、英语、国际经济与贸易、法学、工商管理。调控这些连续造成较大失业量的专业招生结构，并适当调整此类专业的在校学生结构，可以较快地改善总体就业状况。另一方面，河北省2008届高职高专毕业生毕业半年后失业量最多的10个专业占了高职高专失业量的33.1%。
大学毕业生最不愿去区县
从就业城市类型期待来看，河北省2008届大学毕业生对就业地域的期望不是完全合理的。河北省2008届大学毕业生最愿意去的是副省级城市和直辖市，最不愿意去的是区县。
据悉，该报告基于对河北省2008届大学毕业生半年后的调查研究，对2008届河北省大学毕业生的就业流向、就业与收入、工作能力、求职、就业与教育公平、自主创业、读研与留学、大学毕业生的满意度等做出了全面的研究分析。调查覆盖了河北省本科院校与高职高专院校中的101所，本省2008届大学毕业生9223人；在河北省就业的2008届大学毕业生3437人；生源地在河北省的2008届大学毕业生7806人。虽然抽样覆盖了本省大部分的各类学校，但主要指标具有统计科学的总体代表性，不排除个别指标上可能有一定代表性误差

    先说就业形势, 从2008年7月份往后, 基本上投简历, 投一千份才可能有一份回音. 在走访了学生之后(至少三家培训机构), 纷纷表示就业难, 每班就业者寥寥(低达10%), 而不是招生广告上鼓吹的找不到工作者寥寥. 今年春节过后, 形势进一步恶化. 以我所在公司为例, 一个技术维护职位每天都有10人左右来面试, 可见竞争之激烈. 不单无IT经验者难就业, 从周围朋友同学的情况来看(平均5年+经验), 普遍也存在离职后再就业难的问题. 这说明什么问题呢? 那就是职位太少, 太少. 是学生不努力嘛? 不是, 相信大部分还是很努力的. 那么危机何时结束? 我不知道, 今年肯定是结束不了的.

    相信还有很多人, 希望先学好技术, 我个人觉得在目前的金融危机形势下, 看教学视频学习是最好的方式, 既不耽误现有工作, 又能学到技术. 毕竟参加培训根本不能保证就业, 目的也只能是可能学好技术而已. 如果您是为了就业去参加培训, 请您立即停止这种浪费父母血汗钱的行为!

    现在参加培训能得到什么? 可能到手的好技术(需要打好基础外加天天熬夜练习), 一份培训毕业证书, 一份好工作(绝对没有!). 付出的是什么? 1万左右的现金, 4 ~ 5个月的时间, 外加生活费和满腔的希望. 也许过去和将来是参加培训然后就业的好机会, 现在绝对不是.