RequestTimeouts not works as expected

[WeihanLi]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

RequestTimeouts not working, when I try out the request timeouts by following the document here
https://learn.microsoft.com/en-us/aspnet/core/performance/timeouts?view=aspnetcore-8.0

it's not working as expected, no timeout while it should timeout

Expected Behavior

timeout

Steps To Reproduce

test code as below:

using Microsoft.AspNetCore.Http.Timeouts;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRequestTimeouts(options =>
{
    options.DefaultPolicy = new RequestTimeoutPolicy()
    {
        Timeout = TimeSpan.FromSeconds(1),
        WriteTimeoutResponse = context => context.Response.WriteAsync("timeout")
    };
    options.AddPolicy("timeout-2s", TimeSpan.FromSeconds(2));
});
var app = builder.Build();
app.UseRequestTimeouts();
app.Map("/", () => "Hello world");
app.MapGet("/timeout", async () =>
{
    await Task.Delay(TimeSpan.FromSeconds(5));
    return Results.Content("No timeout!", "text/plain");
});
app.MapGet("/timeout-policy", async () =>
{
    await Task.Delay(TimeSpan.FromSeconds(5));
    return Results.Content("No timeout!", "text/plain");
}).WithRequestTimeout("timeout-2s");
app.MapGet("/timeout-catch", [RequestTimeout(1000)]async () =>
{
    try
    {
        await Task.Delay(TimeSpan.FromSeconds(5));
    } 
    catch (TaskCanceledException)
    {
        return Results.Content("Timeout!", "text/plain");
    }
    return Results.Content("No timeout!", "text/plain");
});
app.Run();

all these cases no timeout

Exceptions (if any)

No response

.NET Version

8.0.100-preview.7.23376.3

Anything else?

.NET SDK:
 Version:   8.0.100-preview.7.23376.3
 Commit:    daebeea8ea

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.25947
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\8.0.100-preview.7.23376.3\

.NET workloads installed:
There are no installed workloads to display.

Host:
  Version:      8.0.0-preview.7.23375.6
  Architecture: x64
  Commit:       65b696cf5e
  RID:          win-x64

.NET SDKs installed:
  6.0.408 [C:\Program Files\dotnet\sdk]
  7.0.102 [C:\Program Files\dotnet\sdk]
  7.0.105 [C:\Program Files\dotnet\sdk]
  8.0.100-preview.7.23376.3 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.0-preview.7.23375.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.0-preview.7.23375.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 6.0.13 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.15 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.16 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.0-preview.7.23376.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

[davidfowl]

Timeouts in asynchronous code or cooperative. Your code needs to use the RequestAborted cancellation token in order to get notified.

using Microsoft.AspNetCore.Http.Timeouts;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRequestTimeouts(options =>
{
    options.DefaultPolicy = new RequestTimeoutPolicy()
    {
        Timeout = TimeSpan.FromSeconds(1),
        WriteTimeoutResponse = context => context.Response.WriteAsync("timeout")
    };
    options.AddPolicy("timeout-2s", TimeSpan.FromSeconds(2));
});
var app = builder.Build();
app.UseRequestTimeouts();
app.Map("/", () => "Hello world");
app.MapGet("/timeout", async (CancellationToken token) =>
{
    await Task.Delay(TimeSpan.FromSeconds(5), token);
    return Results.Content("No timeout!", "text/plain");
});
app.MapGet("/timeout-policy", async () =>
{
    await Task.Delay(TimeSpan.FromSeconds(5));
    return Results.Content("No timeout!", "text/plain");
}).WithRequestTimeout("timeout-2s");
app.MapGet("/timeout-catch", [RequestTimeout(1000)] async (CancellationToken token) =>
{
    try
    {
        await Task.Delay(TimeSpan.FromSeconds(5), token);
    } 
    catch (TaskCanceledException)
    {
        return Results.Content("Timeout!", "text/plain");
    }
    return Results.Content("No timeout!", "text/plain");
});
app.Run();

PS: You could that writes the response on timeout should check if the response has already started before doing so.

[WeihanLi]

get it, thanks very much @davidfowl