最近项目上线后遇到exception没有堆栈信息。所以跟踪一下 源码，其中主要的code如下：

// Returns the stack trace as a string.  If no stack trace is        // available, null is returned.        public virtual String StackTrace        {#if FEATURE_CORECLR            [System.Security.SecuritySafeCritical] #endif            get             {                // By default attempt to include file and line number info                return GetStackTrace(true);            }        }        // Computes and returns the stack trace as a string        // Attempts to get source file and line number information if needFileInfo        // is true.  Note that this requires FileIOPermission(PathDiscovery), and so        // will usually fail in CoreCLR.  To avoid the demand and resulting        // SecurityException we can explicitly not even try to get fileinfo.        #if FEATURE_CORECLR        [System.Security.SecurityCritical] // auto-generated        #endif        private string GetStackTrace(bool needFileInfo)        {            string stackTraceString = _stackTraceString;            string remoteStackTraceString = _remoteStackTraceString;#if !FEATURE_CORECLR            if (!needFileInfo)            {                // Filter out file names/paths and line numbers from _stackTraceString and _remoteStackTraceString.                // This is used only when generating stack trace for Watson where the strings must be PII-free.                stackTraceString = StripFileInfo(stackTraceString, false);                remoteStackTraceString = StripFileInfo(remoteStackTraceString, true);            }#endif // !FEATURE_CORECLR            // if no stack trace, try to get one            if (stackTraceString != null)            {                return remoteStackTraceString + stackTraceString;            }            if (_stackTrace == null)            {                return remoteStackTraceString;            }            // Obtain the stack trace string. Note that since Environment.GetStackTrace            // will add the path to the source file if the PDB is present and a demand            // for FileIOPermission(PathDiscovery) succeeds, we need to make sure we             // don't store the stack trace string in the _stackTraceString member variable.            String tempStackTraceString = Environment.GetStackTrace(this, needFileInfo);            return remoteStackTraceString + tempStackTraceString;         }    #if FEATURE_CORECLR        [System.Security.SecuritySafeCritical] #endif        public override String ToString()        {            return ToString(true, true);        }        #if FEATURE_CORECLR        [System.Security.SecurityCritical] // auto-generated        #endif        private String ToString(bool needFileLineInfo, bool needMessage) {            String message = (needMessage ? Message : null);            String s;            if (message == null || message.Length <= 0) {                s = GetClassName();            }            else {                s = GetClassName() + ": " + message;            }            if (_innerException!=null) {                s = s + " ---> " + _innerException.ToString(needFileLineInfo, needMessage) + Environment.NewLine +                 "   " + Environment.GetResourceString("Exception_EndOfInnerExceptionStack");            }            string stackTrace = GetStackTrace(needFileLineInfo);            if (stackTrace != null)            {                s += Environment.NewLine + stackTrace;            }            return s;        }

Exception的StackTrace属性只返回当前对象的站信息，toString方法首先需要获取当前的Message，然后获取内部exception的tostring方法，最后获取 GetStackTrace方法的返回值，该方法主要内容来源于 Environment.GetStackTrace方法，其实现code如下：

internal static String GetStackTrace(Exception e, bool needFileInfo)        {            // Note: Setting needFileInfo to true will start up COM and set our            // apartment state.  Try to not call this when passing "true"             // before the EE's ExecuteMainMethod has had a chance to set up the            // apartment state.  --             StackTrace st;            if (e == null)                st = new StackTrace(needFileInfo);            else                st = new StackTrace(e, needFileInfo);            // Do no include a trailing newline for backwards compatibility            return st.ToString( System.Diagnostics.StackTrace.TraceFormat.Normal );        }

调用的是StackTrace的tostring方法，其实现如下：

internal String ToString(TraceFormat traceFormat)        {            bool displayFilenames = true;   // we'll try, but demand may fail            String word_At = "at";            String inFileLineNum = "in {0}:line {1}";            if(traceFormat != TraceFormat.NoResourceLookup)            {                word_At = Environment.GetResourceString("Word_At");                inFileLineNum = Environment.GetResourceString("StackTrace_InFileLineNumber");            }                        bool fFirstFrame = true;            StringBuilder sb = new StringBuilder(255);            for (int iFrameIndex = 0; iFrameIndex < m_iNumOfFrames; iFrameIndex++)            {                StackFrame sf = GetFrame(iFrameIndex);                MethodBase mb = sf.GetMethod();                if (mb != null)                {                    // We want a newline at the end of every line except for the last                    if (fFirstFrame)                        fFirstFrame = false;                    else                        sb.Append(Environment.NewLine);                                        sb.AppendFormat(CultureInfo.InvariantCulture, "   {0} ", word_At);                    Type t = mb.DeclaringType;                     // if there is a type (non global method) print it                    if (t != null)                    {                                                           sb.Append(t.FullName.Replace('+', '.'));                        sb.Append(".");                    }                    sb.Append(mb.Name);                    // deal with the generic portion of the method                    if (mb is MethodInfo && ((MethodInfo)mb).IsGenericMethod)                    {                        Type[] typars = ((MethodInfo)mb).GetGenericArguments();                        sb.Append("[");                        int k=0;                        bool fFirstTyParam = true;                        while (k < typars.Length)                        {                            if (fFirstTyParam == false)                                sb.Append(",");                            else                                fFirstTyParam = false;                            sb.Append(typars[k].Name);                                         k++;                        }                           sb.Append("]");                        }                    // arguments printing                    sb.Append("(");                    ParameterInfo[] pi = mb.GetParameters();                    bool fFirstParam = true;                    for (int j = 0; j < pi.Length; j++)                    {                        if (fFirstParam == false)                            sb.Append(", ");                        else                            fFirstParam = false;                        String typeName = "
     
      ";                        if (pi[j].ParameterType != null)                            typeName = pi[j].ParameterType.Name;                        sb.Append(typeName + " " + pi[j].Name);                                 }                       sb.Append(")");                    // source location printing                    if (displayFilenames && (sf.GetILOffset() != -1))                    {                        // If we don't have a PDB or PDB-reading is disabled for the module,                        // then the file name will be null.                        String fileName = null;                                                // Getting the filename from a StackFrame is a privileged operation - we won't want                        // to disclose full path names to arbitrarily untrusted code.  Rather than just omit                        // this we could probably trim to just the filename so it's still mostly usefull.                        try                        {                            fileName = sf.GetFileName();                        }#if FEATURE_CAS_POLICY                        catch (NotSupportedException)                        {                            // Having a deprecated stack modifier on the callstack (such as Deny) will cause                            // a NotSupportedException to be thrown.  Since we don't know if the app can                            // access the file names, we'll conservatively hide them.                            displayFilenames = false;                        }#endif // FEATURE_CAS_POLICY                        catch (SecurityException)                        {                            // If the demand for displaying filenames fails, then it won't                            // succeed later in the loop.  Avoid repeated exceptions by not trying again.                            displayFilenames = false;                        }                        if (fileName != null)                         {                            // tack on " in c:\tmp\MyFile.cs:line 5"                            sb.Append(' ');                            sb.AppendFormat(CultureInfo.InvariantCulture, inFileLineNum, fileName, sf.GetFileLineNumber());                        }                    }#if FEATURE_EXCEPTIONDISPATCHINFO                    if (sf.GetIsLastFrameFromForeignExceptionStackTrace())                    {                        sb.Append(Environment.NewLine);                        sb.Append(Environment.GetResourceString("Exception_EndStackTraceFromPreviousThrow"));                    }#endif // FEATURE_EXCEPTIONDISPATCHINFO                }            }            if(traceFormat == TraceFormat.TrailingNewLine)                sb.Append(Environment.NewLine);                        return sb.ToString();         }
     

这个方法最主要的还是   StackFrame sf = GetFrame(iFrameIndex);   它返回跟踪栈的信息。跟踪栈的信息主要来源于StackTrace的构造函数

public StackTrace(Exception e, bool fNeedFileInfo)        {            if (e == null)                throw new ArgumentNullException("e");            Contract.EndContractBlock();            m_iNumOfFrames = 0;            m_iMethodsToSkip = 0;            CaptureStackTrace(METHODS_TO_SKIP, fNeedFileInfo, null, e);        }

核心实现CaptureStackTrace code如下：

private void CaptureStackTrace(int iSkip, bool fNeedFileInfo, Thread targetThread,                                       Exception e)        {            m_iMethodsToSkip += iSkip;                StackFrameHelper StackF = new StackFrameHelper(fNeedFileInfo, targetThread);                GetStackFramesInternal(StackF, 0, e);                m_iNumOfFrames = StackF.GetNumberOfFrames();            if (m_iMethodsToSkip > m_iNumOfFrames)                m_iMethodsToSkip = m_iNumOfFrames;            if (m_iNumOfFrames != 0)            {                frames = new StackFrame[m_iNumOfFrames];                for (int i = 0; i < m_iNumOfFrames; i++)                {                    bool fDummy1 = true;                    bool fDummy2 = true;                    StackFrame sfTemp = new StackFrame(fDummy1, fDummy2);                    sfTemp.SetMethodBase(StackF.GetMethodBase(i));                    sfTemp.SetOffset(StackF.GetOffset(i));                    sfTemp.SetILOffset(StackF.GetILOffset(i));#if FEATURE_EXCEPTIONDISPATCHINFO                    sfTemp.SetIsLastFrameFromForeignExceptionStackTrace(StackF.IsLastFrameFromForeignExceptionStackTrace(i));#endif // FEATURE_EXCEPTIONDISPATCHINFO                    if (fNeedFileInfo)                    {                        sfTemp.SetFileName(StackF.GetFilename (i));                        sfTemp.SetLineNumber(StackF.GetLineNumber(i));                        sfTemp.SetColumnNumber(StackF.GetColumnNumber(i));                    }                     frames[i] = sfTemp;                }                // CalculateFramesToSkip skips all frames in the System.Diagnostics namespace,                // but this is not desired if building a stack trace from an exception.                if (e == null)                    m_iMethodsToSkip += CalculateFramesToSkip(StackF, m_iNumOfFrames);                m_iNumOfFrames -= m_iMethodsToSkip;                if (m_iNumOfFrames < 0)                   {                       m_iNumOfFrames = 0;                   }            }            // In case this is the same object being re-used, set frames to null            else                frames = null;        }

顺便提一下，VS在release模式下是可以调试的，也可以获取堆栈信息。