Exception 0xc0000602 in coreclr.dll during extremely heavy load

[znakeeye]

Description

Targeting .NET 10. Unfortunately, quite hard to reproduce. Maybe you can find some clues in the provided crash offset.

In a Release build, my app runs an exhaustive search on 32 cores - all running at very high load, close to 100%. Sometimes, the app crashes with the following entry in Event Viewer:

Unhandled exception at 0x00007FFF238B1F46 (coreclr.dll) in Foo.exe: 0xC0000602:
A fail fast exception occurred. Exception handlers will not be invoked and
the process will be terminated immediately.

Faulting module name: coreclr.dll, version: 10.0.25.16302, time stamp: 0x67d31977
Exception code: 0xc0000602
Fault offset: 0x0000000000311f46
Faulting module path:
C:\Program Files\dotnet\shared\Microsoft.NETCore.App\10.0.0-preview.2.25163.2\coreclr.dll

I have not been able to isolate the issue, but here are some clues:

• AllowUnsafeBlocks enabled, allowing for LibraryImportAttribute
• Using Parallel.ForEach
• Using ThreadLocal<int> with trackAllValues = true occasionally reading its Values collection.
• Using ThreadStaticAttribute
• Interlocked.Increment used occasionally to update the UI.
• Semaphore (lock object) used occasionally to update the UI.
• No GC at all.

Reproduction Steps

Very hard to reproduce. Will let you know if I can figure out the steps...

Expected behavior

Certainly we should not get a native exception in coreclr.dll in a managed app?

Actual behavior

Native exception from coreclr.dll crashes our managed app.

Regression?

No response

Known Workarounds

No response

Configuration

• .NET 10.0.0-preview.2.25163.2
• Windows 11 Pro Version 24H2 (OS Build 26100.4652)
• Any CPU (running on x64)

Other information

No response

[jkotas]

The crash offset does not tell much. Any chance you can collect crash dump for the crash and extract stacktrace from it using windbg debugger?

Instructions are for collecting crash dumps on Windows are at https://learn.microsoft.com/en-us/windows/win32/wer/collecting-user-mode-dumps (Use DumpType: 2 - Full dump).

.NET 10.0.0-preview.2

This is very old preview. You should update to current preview build (preview.6)

[znakeeye]

The crash offset does not tell much. Any chance you can collect crash dump for the crash and extract stacktrace from it using windbg debugger?

Instructions are for collecting crash dumps on Windows are at https://learn.microsoft.com/en-us/windows/win32/wer/collecting-user-mode-dumps (Use DumpType: 2 - Full dump).

.NET 10.0.0-preview.2

This is very old preview. You should update to current preview build (preview.6)

Good catch! I thought I was up-to-date since I keep running the Visual Studio updater, but that's obviously not enough when dealing with Preview releases.

Will update to Preview 6 and enable Full dumps 👍