Fix pinning of frames

Author: xoofx

src/Ultra.Core/Parser/UltraSamplerParser.cs

@@ -67,7 +67,7 @@ public sealed class UltraNativeCallstackTraceEvent : TraceEvent
     private static readonly string[] _payloadNames =
     [
         nameof(FrameThreadId),
-        nameof(FrameCount),
+        nameof(FrameSize),
         nameof(FrameAddresses)
     ];
 
@@ -80,9 +80,9 @@ internal UltraNativeCallstackTraceEvent(Action<UltraNativeCallstackTraceEvent>?
 
     public ulong FrameThreadId => (ulong)GetInt64At(0);
 
-    public int FrameCount => GetInt32At(8);
+    public int FrameSize => GetInt32At(8);
 
-    public unsafe ReadOnlySpan<ulong> FrameAddresses => new((byte*)DataStart + 12, FrameCount);
+    public unsafe ReadOnlySpan<ulong> FrameAddresses => new((byte*)DataStart + 12, FrameSize / sizeof(ulong));
 
     /// <inheritdoc />
 
@@ -93,7 +93,7 @@ public override object PayloadValue(int index)
             case 0:
                 return FrameThreadId;
             case 1:
-                return FrameCount;
+                return FrameSize;
             case 2:
                 return FrameAddresses.ToArray();
             default:

src/Ultra.Sampler/MacOS/MacOSUltraSampler.cs

@@ -19,7 +19,7 @@ internal unsafe class MacOSUltraSampler : UltraSampler
     private readonly AutoResetEvent _resumeCaptureThread;
 
     private const int MaximumFrames = 4096;
-    private readonly ulong[] _frames = new ulong[MaximumFrames];
+    private readonly ulong[] _frames;
 
     private const int DefaultImageCount = 1024;
     private UnsafeList<NativeModuleEvent> _moduleEvents = new(DefaultImageCount);
@@ -33,6 +33,7 @@ internal unsafe class MacOSUltraSampler : UltraSampler
 
     public MacOSUltraSampler()
     {
+        _frames = GC.AllocateArray<ulong>(4096, true);
         _resumeCaptureThread = new AutoResetEvent(false);
 
         _callbackDyldAdded = new MacOSLibSystem.dyld_register_callback(CallbackDyldAdded);