Defer resolution of StackTrace debug info until use

src/coreclr/System.Private.CoreLib/src/System/Diagnostics/StackFrameHelper.cs

@@ -94,8 +94,40 @@ public StackFrameHelper()
         internal void InitializeSourceInfo(bool fNeedFileInfo, Exception? exception)
         {
             StackTrace.GetStackFramesInternal(this, fNeedFileInfo, exception);
+        }
+
+        public MethodBase? GetMethodBase(int i)
+        {
+            // There may be a better way to do this.
+            // we got RuntimeMethodHandles here and we need to go to MethodBase
+            // but we don't know whether the reflection info has been initialized
+            // or not. So we call GetMethods and GetConstructors on the type
+            // and then we fetch the proper MethodBase!!
+            IntPtr mh = rgMethodHandle![i];
+
+            if (mh == IntPtr.Zero)
+                return null;
+
+            IRuntimeMethodInfo? mhReal = RuntimeMethodHandle.GetTypicalMethodDefinition(new RuntimeMethodInfoStub(new RuntimeMethodHandleInternal(mh), this));
+
+            return RuntimeType.GetMethodBase(mhReal);
+        }
+
+        private void InitializeFrameSourceInfo(int index)
+        {
+            // rgiMethodToken is null if file info wasn't requested when collecting the stack trace.
+            if (rgiMethodToken == null)
+                return;
 
-            if (!fNeedFileInfo)
+            // We use rgiMethodToken[i] to indicate whether we've initialized the info for this frame.
+            // If the native code set it to zero, then information is already initialized from the native
+            // symbol reader. If the native code set it to non-zero, then we're supposed to use the managed
+            // symbol reader to try to resolve debug information.
+            //
+            // This is the only purpose the field has, however, so we can assign it to zero AFTER resolving
+            // symbol information to indicate that it's already been resolved without causing any issues
+            // elsewhere.
+            if (rgiMethodToken[index] == 0)
                 return;
 
             // Check if this function is being reentered because of an exception in the code below
@@ -112,17 +144,12 @@ internal void InitializeSourceInfo(bool fNeedFileInfo, Exception? exception)
                     Interlocked.CompareExchange(ref s_stackTraceSymbolsCache, CreateStackTraceSymbols(), null);
                 }
 
-                for (int index = 0; index < iFrameCount; index++)
-                {
-                    // If there was some reason not to try get the symbols from the portable PDB reader like the module was
-                    // ENC or the source/line info was already retrieved, the method token is 0.
-                    if (rgiMethodToken![index] != 0)
-                    {
-                        GetSourceLineInfo(s_stackTraceSymbolsCache!, rgAssembly![index], rgAssemblyPath![index]!, rgLoadedPeAddress![index], rgiLoadedPeSize![index], rgiIsFileLayout![index],
-                            rgInMemoryPdbAddress![index], rgiInMemoryPdbSize![index], rgiMethodToken![index],
-                            rgiILOffset![index], out rgFilename![index], out rgiLineNumber![index], out rgiColumnNumber![index]);
-                    }
-                }
+                GetSourceLineInfo(s_stackTraceSymbolsCache!, rgAssembly![index], rgAssemblyPath![index]!, rgLoadedPeAddress![index], rgiLoadedPeSize![index], rgiIsFileLayout![index],
+                    rgInMemoryPdbAddress![index], rgiInMemoryPdbSize![index], rgiMethodToken![index],
+                    rgiILOffset![index], out rgFilename![index], out rgiLineNumber![index], out rgiColumnNumber![index]);
+
+                // Make sure we mark down that debug information for this frame was resolved
+                rgiMethodToken[index] = 0;
             }
             catch
             {
@@ -133,28 +160,37 @@ internal void InitializeSourceInfo(bool fNeedFileInfo, Exception? exception)
             }
         }
 
-        public MethodBase? GetMethodBase(int i)
-        {
-            // There may be a better way to do this.
-            // we got RuntimeMethodHandles here and we need to go to MethodBase
-            // but we don't know whether the reflection info has been initialized
-            // or not. So we call GetMethods and GetConstructors on the type
-            // and then we fetch the proper MethodBase!!
-            IntPtr mh = rgMethodHandle![i];
-
-            if (mh == IntPtr.Zero)
-                return null;
-
-            IRuntimeMethodInfo? mhReal = RuntimeMethodHandle.GetTypicalMethodDefinition(new RuntimeMethodInfoStub(new RuntimeMethodHandleInternal(mh), this));
-
-            return RuntimeType.GetMethodBase(mhReal);
-        }
-
         public int GetOffset(int i) { return rgiOffset![i]; }
         public int GetILOffset(int i) { return rgiILOffset![i]; }
-        public string? GetFilename(int i) { return rgFilename?[i]; }
-        public int GetLineNumber(int i) { return rgiLineNumber == null ? 0 : rgiLineNumber[i]; }
-        public int GetColumnNumber(int i) { return rgiColumnNumber == null ? 0 : rgiColumnNumber[i]; }
+        public string? GetFilename(int i)
+        {
+            InitializeFrameSourceInfo(i);
+            return rgFilename?[i];
+        }
+        public int GetLineNumber(int i)
+        {
+            if (rgiLineNumber == null)
+            {
+                return 0;
+            }
+            else
+            {
+                InitializeFrameSourceInfo(i);
+                return rgiLineNumber[i];
+            }
+        }
+        public int GetColumnNumber(int i)
+        {
+            if (rgiColumnNumber == null)
+            {
+                return 0;
+            }
+            else
+            {
+                InitializeFrameSourceInfo(i);
+                return rgiColumnNumber[i];
+            }
+        }
 
         public bool IsLastFrameFromForeignExceptionStackTrace(int i)
         {

src/coreclr/System.Private.CoreLib/src/System/Diagnostics/StackTrace.CoreCLR.cs

@@ -4,11 +4,15 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Threading;
 
 namespace System.Diagnostics
 {
     public partial class StackTrace
     {
+        private StackFrameHelper? _stackFrameHelper;
+        private bool _fNeedFileInfo;
+
         [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "StackTrace_GetStackFramesInternal")]
         private static partial void GetStackFramesInternal(ObjectHandleOnStack sfh, [MarshalAs(UnmanagedType.Bool)] bool fNeedFileInfo, ObjectHandleOnStack e);
 
@@ -66,30 +70,47 @@ private void CaptureStackTrace(int skipFrames, bool fNeedFileInfo, Exception? e)
             StackF.InitializeSourceInfo(fNeedFileInfo, e);
 
             _numOfFrames = StackF.GetNumberOfFrames();
+            _stackFrameHelper = StackF;
 
             if (_methodsToSkip > _numOfFrames)
                 _methodsToSkip = _numOfFrames;
 
-            if (_numOfFrames != 0)
+            _fNeedFileInfo = fNeedFileInfo;
+
+            // 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)
+                _methodsToSkip += CalculateFramesToSkip(_stackFrameHelper, _numOfFrames);
+
+            _numOfFrames -= _methodsToSkip;
+            if (_numOfFrames < 0)
             {
-                _stackFrames = new StackFrame[_numOfFrames];
+                _numOfFrames = 0;
+            }
+        }
 
-                for (int i = 0; i < _numOfFrames; i++)
-                {
-                    _stackFrames[i] = new StackFrame(StackF, i, fNeedFileInfo);
-                }
+        /// <summary>
+        /// Gets the <see cref="StackFrame"/> array for this StackTrace, possibly creating if needed.
+        /// </summary>
+        /// <returns></returns>
+        private StackFrame[] GetFramesCore()
+        {
+            if (_numOfFrames != 0 && _stackFrames == null)
+            {
+                Debug.Assert(_stackFrameHelper != null);
 
-                // 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)
-                    _methodsToSkip += CalculateFramesToSkip(StackF, _numOfFrames);
+                // the frame array should contain all frames (even skipped ones!)
+                StackFrame[] stackFrames = new StackFrame[_stackFrameHelper.GetNumberOfFrames()];
 
-                _numOfFrames -= _methodsToSkip;
-                if (_numOfFrames < 0)
+                for (int i = 0; i < stackFrames.Length; i++)
                 {
-                    _numOfFrames = 0;
+                    stackFrames[i] = new StackFrame(_stackFrameHelper, i, _fNeedFileInfo);
                 }
+
+                Interlocked.CompareExchange(ref _stackFrames, stackFrames, null);
             }
+
+            return _stackFrames ?? [];
         }
     }
 }

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Diagnostics/StackTrace.NativeAot.cs

@@ -95,5 +95,10 @@ internal void ToString(TraceFormat traceFormat, StringBuilder builder)
                 builder.AppendLine();
         }
 #endif
+
+        private StackFrame[] GetFramesCore()
+        {
+            return _stackFrames ?? [];
+        }
     }
 }

src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackTrace.cs

@@ -156,8 +156,9 @@ public StackTrace(IEnumerable<StackFrame> frames)
         /// </summary>
         public virtual StackFrame? GetFrame(int index)
         {
-            if (_stackFrames != null && index < _numOfFrames && index >= 0)
-                return _stackFrames[index + _methodsToSkip];
+            StackFrame[] stackFrames = GetFramesCore();
+            if (stackFrames != null && index < _numOfFrames && index >= 0)
+                return stackFrames[index + _methodsToSkip];
 
             return null;
         }
@@ -170,13 +171,14 @@ public StackTrace(IEnumerable<StackFrame> frames)
         /// </summary>
         public virtual StackFrame[] GetFrames()
         {
-            if (_stackFrames == null || _numOfFrames <= 0)
+            StackFrame[] stackFrames = GetFramesCore();
+            if (stackFrames == null || _numOfFrames <= 0)
                 return Array.Empty<StackFrame>();
 
             // We have to return a subset of the array. Unfortunately this
             // means we have to allocate a new array and copy over.
             StackFrame[] array = new StackFrame[_numOfFrames];
-            Array.Copy(_stackFrames, _methodsToSkip, array, 0, _numOfFrames);
+            Array.Copy(stackFrames, _methodsToSkip, array, 0, _numOfFrames);
             return array;
         }
 

src/mono/System.Private.CoreLib/src/System/Diagnostics/StackTrace.Mono.cs

@@ -92,5 +92,10 @@ private void InitializeForException(Exception e, int skipFrames, bool needFileIn
                 _stackFrames[foreignFrames + i] = new StackFrame(frames[i], needFileInfo);
             }
         }
+
+        private StackFrame[] GetFramesCore()
+        {
+            return _stackFrames ?? [];
+        }
     }
 }