process terminated due to unhandled exception "DivideByZeroException"

[HTH-FiANTEC]

Description

We've an application server based on .NET8 which gets terminated by a DivideByZeroException from System.Threading.PortableThreadPool.HillClimbing.Update.

Reproduction Steps

We're not able to identifiy the specific function as the application is terminated.

Expected behavior

The exception can be handled by application code to minimize corrupted state of data and application. A possibility to identify the producer of the error.

Actual behavior

From the windows event logs, we receive the following information:

CoreCLR Version: 8.0.1725.26602 .NET Version: 8.0.17 Description: The process was terminated due to an unhandled exception. Exception Info: System.DivideByZeroException: Attempted to divide by zero. at System.Threading.PortableThreadPool.HillClimbing.Update(Int32 currentThreadCount, Double sampleDurationSeconds, Int32 numCompletions) at System.Threading.PortableThreadPool.AdjustMaxWorkersActive() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()

Reference found: https://source.dot.net/#System.Private.CoreLib/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs

Regression?

We're using the framework since .NET-core 3.1 without facing this issue. The first occurence was in July this year.

Known Workarounds

No response

Configuration

CoreCLR Version: 8.0.1725.26602
.NET Version: 8.0.17
x64
Windows Server 2022

Other information

No response

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[mangod9]

Are you able to capture a dump when the issue occurs?

[HTH-FiANTEC]

Unfortunately, it only occurs in the customer environment and cannot really be provoked.

Are there any points that can be checked that could lead to the error described?
Can it be narrowed down to specific framework components/structures?

[HTH-FiANTEC]

Hello,

We have now been able to narrow down the error and identify the cause in a DllImport. A DLL is imported from Delphi and called. Here is an example to provoke the error:

library Project10;

uses System.Math;

procedure SetDivideByZeroExceptionMask;
begin
  SetExceptionMask(GetExceptionMask - [exZeroDivide]);
end;

exports
  SetDivideByZeroExceptionMask;

begin
end.

If this code is now called using the following example, the error can be reproduced:

class FpuCrashSimulator
{
    [DllImport("Project10.dll")]
    private static extern void SetDivideByZeroExceptionMask();

    public static void DoIt()
    {
        SetDivideByZeroExceptionMask();
        try
        {
            double x = 1.0;
            double y = 0.0;
            double z = x / y;   // DivideByZeroException
            Console.WriteLine(z);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.GetType());
        }
    }
}

With SetExceptionMask(GetExceptionMask - [exZeroDivide]), the DivideByZeroException occurs,
but not with SetExceptionMask(GetExceptionMask + [exZeroDivide]).

[tannergooding]

.NET does not support setting IEEE 754 Exception Handling and having it enabled for managed code can cause undefined behavior.

If native code enables it for its own isolated scenario, it needs to be disabled before returning control back to managed.

See also #109997

[dotnet-policy-service]

This issue has been marked needs-author-action and may be missing some important information.