Should ShutdownTimeout be set to shorter value then the *host* shutdown period?

[ramonsmits]

According to the inline docs Shut

Gets or sets the default timeout

Source:

runtime/src/libraries/Microsoft.Extensions.Hosting/src/HostOptions.cs

Line 24 in 80aa709

public TimeSpan ShutdownTimeout { get; set; } = TimeSpan.FromSeconds(30);

The webhost:

• https://github.com/dotnet/aspnetcore/blob/1f82fa558dd7afb0ac94a43c7b80f40499bad98c/src/Hosting/Hosting/src/Internal/WebHost.cs#L290

• runtime/src/libraries/Microsoft.Extensions.Hosting/src/Internal/Host.cs

  Line 224 in 6d344b3

  cts.CancelAfter(_options.ShutdownTimeout);

What I see happening is that this value is often set to the duration that the host allows for graceful termination.

For example, the default is 30 seconds which is aligned with the windows server default.

However, what is the point of setting this to the same value as the hosting environment as usually this results in process termination?

To me it seems that ShutdownTimeout should be set to for example 25 seconds. After 25 seconds, shutdown is cancelled and now 5 seconds are remaining for an ungraceful shutdown until the host will terminate the process.

As on Windows I think the default duration is 20 seconds, should this value then be set to 15 seconds?

WindowsServiceLifetime and RequestAdditionalTime

I've also looked at the WindowsServiceLifetime. It has some delay logic that uses ShutdownTimeout in the OnStop and OnShutdown. However, I expected it to invokeServiceBase.RequestAdditionalTime which it does not. I've searched the whole repo on RequestAdditionalTime and it isn't used.

Meaning, you can't set ShutdownTimeout to for example 2 minutes and expect Windows Server to allow your application longer to its maximum default of 125 seconds because RequestAdditionalTime isn't invoked.

Source: https://github.com/dotnet/runtime/blob/v9.0.2/src/libraries/Microsoft.Extensions.Hosting.WindowsServices/src/WindowsServiceLifetime.cs

This is also mentioned at:

• UseWindowsService should support some method to invoke ServiceBase.RequestAdditionalTime #75276

Unfortunately, that issue was incorectly marked as resolved.

It does list alternatives:

• Inherit from WindowsServiceLifetime, and override OnStop and OnShutdown and set RequestAdditionalTime to ShutdownTimeout + TimeSpan.FromSeconds(5) to allow for a 5 second cancellation period.
• Resolve the IHostLifetime, cast it to WindowsServiceLifetime:
  • ((WindowsServiceLifetime)hostLifetime).RequestAdditionalTime(..)

So in short:

1. Why is the default value for ShutdownTimeout 30 seconds while in most environments its shorter (windows service 20 seconds, docker 10 seconds).
2. You should likely never set ShutdownTimeout to the same value, as that will align process terminination with cancellation. Meaning cooperative cancellation likely will not be executed.
3. Why isn't WindowsServiceLifetime invoking RequestAdditionalTime that included a short timespan (5 seconds?) to allow cooperative cancellation?

[lbussell]

This doesn't look related to the .NET container images. I am transferring this discussion to dotnet/runtime.