Bad Process.StartTime in .NET Core 3.1 on macOS

[mattjohnsonpint]

Description

The value returned from System.Diagnostics.Process.StartTime is wildly incorrect when run on .NET Core 3.1 (runtime 3.1.22) on macOS 12.2.1 with M1 (Apple Silicon / arm64) processor. The problem does not occur on .NET 6.0 or 5.0, nor does it occur on .NET Core 3.1 running on macOS with an Intel (x64) processor.

Reproduction Steps

Following this guidance, install the following SDKs on macOS:

• 6.0.200 arm64
• 6.0.200 x64
• 5.0.405 x64
• 3.1.416 x64

Create a new console app:

test.csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net6.0;net5.0;netcoreapp3.1</TargetFrameworks>
  </PropertyGroup>
</Project>

Program.cs:

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace ConsoleApp1
{
    public static class Program
    {
        public static void Main()
        {
            var processStartTime = Process.GetCurrentProcess().StartTime.ToUniversalTime();
            var utcNow = DateTime.UtcNow;
            var delta = utcNow - processStartTime;

            Console.WriteLine($"OS Architecture: {RuntimeInformation.OSArchitecture}");
            Console.WriteLine($"Framework: {RuntimeInformation.FrameworkDescription}");
            Console.WriteLine($"Process.StartTime: {processStartTime:o}");
            Console.WriteLine($"DateTime.UtcNow: {utcNow:o}");
            Console.WriteLine($"Delta: {delta}");
            Console.WriteLine();
        }
    }
}

Run the program under the various runtimes and observe the results.

Expected behavior

The process start time should be very close to DateTime.UtcNow (delta near zero) in all cases.

Actual behavior

The output is correct on .NET 6 and 5, but wildly incorrect on .NET Core 3.1 (LTS).

% dotnet run -f net6.0
OS Architecture: Arm64
Framework: .NET 6.0.2
Process.StartTime: 2022-03-03T22:26:01.6263462Z
DateTime.UtcNow: 2022-03-03T22:26:01.7393750Z
Delta: 00:00:00.1130288

% dotnet run -f net6.0 -a x64
OS Architecture: X64
Framework: .NET 6.0.2
Process.StartTime: 2022-03-03T22:26:07.7978340Z
DateTime.UtcNow: 2022-03-03T22:26:07.9519200Z
Delta: 00:00:00.1540860

% dotnet run -f net5.0       
OS Architecture: X64
Framework: .NET 5.0.14
Process.StartTime: 2022-03-03T22:26:18.0786000Z
DateTime.UtcNow: 2022-03-03T22:26:18.2399030Z
Delta: 00:00:00.1613030

% dotnet run -f netcoreapp3.1
OS Architecture: X64
Framework: .NET Core 3.1.22
Process.StartTime: 2022-03-03T06:58:55.5796520Z
DateTime.UtcNow: 2022-03-03T22:26:51.5452700Z
Delta: 15:27:55.9656180

Regression?

The symptoms are similar to #19928, but that was resolved very long ago in .NET Core 2.0.

That it is working in .NET 5 and 6, might be related to #30241

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

The value returned from System.Diagnostics.Process.StartTime is wildly incorrect when run on .NET Core 3.1 (runtime 3.1.22) on macOS 12.2.1 with M1 (Apple Silicon / arm64) processor. The problem does not occur on .NET 6.0 or 5.0.

Reproduction Steps

Following [this guidance](dotnet/sdk#22380 (comment), install the following SDKs on macOS:

• 6.0.200 arm64
• 6.0.200 x64
• 5.0.405 x64
• 3.1.416 x64

Create a new console app:

test.csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net6.0;net5.0;netcoreapp3.1</TargetFrameworks>
  </PropertyGroup>
</Project>

Program.cs:

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace ConsoleApp1
{
    public static class Program
    {
        public static void Main()
        {
            var processStartTime = Process.GetCurrentProcess().StartTime.ToUniversalTime();
            var utcNow = DateTime.UtcNow;
            var delta = utcNow - processStartTime;

            Console.WriteLine($"OS Architecture: {RuntimeInformation.OSArchitecture}");
            Console.WriteLine($"Framework: {RuntimeInformation.FrameworkDescription}");
            Console.WriteLine($"Process.StartTime: {processStartTime:o}");
            Console.WriteLine($"DateTime.UtcNow: {utcNow:o}");
            Console.WriteLine($"Delta: {delta}");
            Console.WriteLine();
        }
    }
}

Run the program under the various runtimes and observe the results.

Expected behavior

The process start time should be very close to DateTime.UtcNow (delta near zero) in all cases.

Actual behavior

The output is correct on .NET 6 and 5, but wildly incorrect on .NET Core 3.1 (LTS).

% dotnet run -f net6.0
OS Architecture: Arm64
Framework: .NET 6.0.2
Process.StartTime: 2022-03-03T22:26:01.6263462Z
DateTime.UtcNow: 2022-03-03T22:26:01.7393750Z
Delta: 00:00:00.1130288

% dotnet run -f net6.0 -a x64
OS Architecture: X64
Framework: .NET 6.0.2
Process.StartTime: 2022-03-03T22:26:07.7978340Z
DateTime.UtcNow: 2022-03-03T22:26:07.9519200Z
Delta: 00:00:00.1540860

% dotnet run -f net5.0       
OS Architecture: X64
Framework: .NET 5.0.14
Process.StartTime: 2022-03-03T22:26:18.0786000Z
DateTime.UtcNow: 2022-03-03T22:26:18.2399030Z
Delta: 00:00:00.1613030

% dotnet run -f netcoreapp3.1
OS Architecture: X64
Framework: .NET Core 3.1.22
Process.StartTime: 2022-03-03T06:58:55.5796520Z
DateTime.UtcNow: 2022-03-03T22:26:51.5452700Z
Delta: 15:27:55.9656180

Regression?

The symptoms are similar to #19928, but that was resolve very long ago in .NET Core 2.0.

That it is working in .NET 5 and 6 might be related to #30241

Known Workarounds

No response

Configuration

No response

Other information

@tarekgh

Author:	mattjohnsonpint
Assignees:	-
Labels:	area-System.Diagnostics.Process, untriaged
Milestone:	-

[mattjohnsonpint]

• @tarekgh

[mattjohnsonpint]

The bad result also occurs on .NET Core 2.1, but since it's unsupported I expect that won't get resolved.

[bruno-garcia]

I'm running macOS x64 and I get:

➜ dotnet run -f netcoreapp3.1
OS Architecture: X64
Framework: .NET Core 3.1.22
Process.StartTime: 2022-03-03T23:37:39.8810980Z
DateTime.UtcNow: 2022-03-03T23:37:40.9433880Z
Delta: 00:00:01.0622900

➜ dotnet run -f net5.0       
OS Architecture: X64
Framework: .NET 5.0.13
Process.StartTime: 2022-03-03T23:37:51.3093380Z
DateTime.UtcNow: 2022-03-03T23:37:52.1889820Z
Delta: 00:00:00.8796440

➜ dotnet run -f net6.0
OS Architecture: X64
Framework: .NET 6.0.1
Process.StartTime: 2022-03-03T23:37:56.5150970Z
DateTime.UtcNow: 2022-03-03T23:37:56.5868800Z
Delta: 00:00:00.0717830

dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.101
 Commit:    ef49f6213a

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  11.0
 OS Platform: Darwin
 RID:         osx.10.16-x64
 Base Path:   /usr/local/share/dotnet/sdk/6.0.101/

Host (useful for support):
  Version: 6.0.1
  Commit:  3a25a7f1cc

.NET SDKs installed:
  2.1.818 [/usr/local/share/dotnet/sdk]
  3.1.414 [/usr/local/share/dotnet/sdk]
  3.1.415 [/usr/local/share/dotnet/sdk]
  3.1.416 [/usr/local/share/dotnet/sdk]
  5.0.402 [/usr/local/share/dotnet/sdk]
  5.0.403 [/usr/local/share/dotnet/sdk]
  5.0.404 [/usr/local/share/dotnet/sdk]
  6.0.100-rc.2.21505.57 [/usr/local/share/dotnet/sdk]
  6.0.100 [/usr/local/share/dotnet/sdk]
  6.0.101 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.20 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.21 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.22 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.11 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.12 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.13 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0-rc.2.21480.10 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.20 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.21 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.22 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.11 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.12 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.13 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.0-rc.2.21480.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

[mattjohnsonpint]

Thanks @bruno-garcia. I updated the issue to reflect that it only occurs on M1 hardware, not on Intel.

[jozkee]

@danmoseley @jeffhandley before investing time into porting/ensuring that dotnet/corefx#39572 fixes this issue, can you say if this would meet the bar for 3.1 servicing?

[tarekgh]

@mattjohnsonpint it is nice to see you around github :-)

I am wondering if this is something really blocking you? or can migrate to .NET 6.0 to work around this issue? telling more about your scenario will be helpful here.

[danmoseley]

occurs on M1 hardware, not on Intel.

That's curious, it's not obvious to me that dotnet/corefx#39572 is Arm64 specific.

[mattjohnsonpint]

Hi @tarekgh! I'm working at Sentry now, on their client SDKs with @bruno-garcia. This came up because Process.StartTime is used in a core path (that our unit tests hit), and we support clients that are building for many versions of .NET. We're working around the test failures for now by skipping, but that's just burying the issue. In reality, we have customers who have built .NET Core 3.1 apps, and may be deploying them to newer hardware, such as the M1 MacBooks. We'll have erroneous data for that subset of customers using Sentry unless this is fixed in the runtime.

[jozkee]

Linking similar Linux issue #64742.