我们在生产环境中使用简单的 ASP.NET Web 应用程序（ASP.NET 2.0），有 2 个 Web 服务器，每个 Web 服务器有 64GB RAM 和 32 个核心。生产站点有时会突然将两台服务器上的 CPU 飙升至 90-100%（当然只有 w3wp.exe）。此外，我们发现 pagefile.sys 也变得太大（曾经超过 70GB）。我们对 w3wp.exe 进程进行了一些转储，发现了一些有趣的结果。例如，我们发现一个线程仅执行就需要 22 分钟，
Thread 2840
General Operation Info
Type Unknown Operation
Dumps present All dumps
Elapsed Time (unknown)
Thread Info
Entry point mscorwks!Thread::intermediateThreadProc
System ID 2840 (0xB18)
Create time 21/01/2018 10:55:34
All functions in this operation (excludes boiler-plate functions)
System.Security.CodeAccessSecurityEngine.Assert(System.Security.CodeAccessPermission, System.Threading.StackCrawlMark ByRef)
System.Security.CodeAccessPermission.Assert()
System.Security.PermissionToken.FindToken(System.Type)
System.Security.PermissionSet.RemovePermission(System.Type)
System.Security.PermissionSet.CopyWithNoIdentityPermissions()
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
System.Security.CodeAccessSecurityEngine.Assert(System.Security.CodeAccessPermission, System.Threading.StackCrawlMark ByRef)
System.Security.CodeAccessPermission.Assert()
System.Security.PermissionToken.FindToken(System.Type)
System.Security.PermissionSet.RemovePermission(System.Type)
System.Security.PermissionSet.CopyWithNoIdentityPermissions()
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
User Time 00:22:42.359
Kernel time 00:01:59.765
我的问题是为什么 CodeAccessSecurityEngine 要花 22 分钟才能执行？
我们在转储中发现至少有 48 个线程使用 CodeAccessSecurityEngine 并耗费大量时间。更多示例如下：
Thread 8092
General Operation Info
Type Unknown Operation
Dumps present All dumps
Elapsed Time (unknown)
Thread Info
Entry point mscorwks!Thread::intermediateThreadProc
System ID 8092 (0x1F9C)
Create time 21/01/2018 10:25:40
System.String.InternalSubString(Int32, Int32, Boolean)
System.RuntimeType.SplitName(System.String, System.String ByRef, System.String ByRef)
System.RuntimeType.GetInterface(System.String, Boolean)
System.Security.PermissionToken.FindToken(System.Type)
System.Security.PermissionSet.RemovePermission(System.Type)
System.Security.PermissionSet.CopyWithNoIdentityPermissions()
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
User Time 00:26:49.734
Kernel time 00:02:38.296
-------------------------------------------------------------------------------
Thread 2360
General Operation Info
Type Unknown Operation
Dumps present All dumps
Elapsed Time (unknown)
Thread Info
Entry point mscorwks!Thread::intermediateThreadProc
System ID 2360 (0x938)
Create time 21/01/2018 10:47:53
System.Collections.Generic.List`1[[System.__Canon, mscorlib]].set_Capacity(Int32)
System.Collections.Generic.List`1[[System.__Canon, mscorlib]].EnsureCapacity(Int32)
System.Collections.Generic.List`1[[System.__Canon, mscorlib]].Add(System.__Canon)
System.RuntimeType.GetMethodCandidates(System.String, System.Reflection.BindingFlags, System.Reflection.CallingConventions, System.Type[], Boolean)
System.RuntimeType.GetMethodImpl(System.String, System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])
System.Security.PermissionToken.FindToken(System.Type)
System.Security.PermissionSet.RemovePermission(System.Type)
System.Security.PermissionSet.CopyWithNoIdentityPermissions()
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
User Time 00:25:37.671
Kernel time 00:02:29.953
-------------------------------------------------------------------------------
Thread 7008
General Operation Info
Type Unknown Operation
Dumps present All dumps
Elapsed Time (unknown)
Thread Info
Entry point mscorwks!Thread::intermediateThreadProc
System ID 7008 (0x1B60)
Create time 21/01/2018 10:54:20
System.Reflection.MethodBase.CheckArguments(System.Object[], System.Reflection.Binder, System.Reflection.BindingFlags, System.Globalization.CultureInfo, System.Signature)
System.Reflection.RuntimeConstructorInfo.Invoke(System.Reflection.BindingFlags, System.Reflection.Binder, System.Object[], System.Globalization.CultureInfo)
System.RuntimeType.CreateInstanceImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Object[], System.Globalization.CultureInfo, System.Object[])
System.Security.PermissionSet.AddPermission(System.Security.IPermission)
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
User Time 00:23:01.656
Kernel time 00:02:04.625
-------------------------------------------------------------------------------
Thread 5584
General Operation Info
Type Unknown Operation
Dumps present All dumps
Elapsed Time (unknown)
Thread Info
Entry point mscorwks!Thread::intermediateThreadProc
System ID 5584 (0x15D0)
Create time 21/01/2018 10:53:13
System.Security.CodeAccessSecurityEngine.ReflectionTargetDemandHelper(Int32, System.Security.PermissionSet, System.Threading.CompressedStack)
User Time 00:23:40.421
Kernel time 00:02:08.296
已使用调试诊断进行转储和分析，如下所示 https://docs.microsoft.com/en-us/iis/troubleshoot/performance-issues/troubleshooting-high-cpu-in-an-iis-7x-application-pool
CodeAccessSecurityEngine 真的是罪魁祸首吗？还是其他什么？