IFeatureCollection has been disposed when trying to access HttpContext.Request.Headers

Steps to reprodce

1. Create a simple API ASP.NET Core 3.1 Web Application using Visual Studio 2019 template.
2. In the handler method, add access to HttpContext.Request.Headers.
3. Create a REST client that sends many requests simultaneously.

The result is that eventually, a System.ObjectDisposedException will be thrown upon accessing HttpContext.Request.Headers.

Startup code

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<WeatherForecastController>();
        services.AddMvc().AddControllersAsServices();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();
        app.UseRouting();
        app.UseAuthorization();
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

Controller code

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    private readonly ILogger<WeatherForecastController> _logger;
    public WeatherForecastController(ILogger<WeatherForecastController> logger)
    {
        _logger = logger;
    }

    [HttpGet]
    public IEnumerable<WeatherForecast> Get()
    {
        var headers = HttpContext.Request.Headers;
        var rng = new Random();
        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
        {
            Date = DateTime.Now.AddDays(index),
            TemperatureC = rng.Next(-20, 55),
            Summary = Summaries[rng.Next(Summaries.Length)]
        })
        .ToArray();
    }
}

Client code

static void Main(string[] args)
{
    Parallel.For(0, 3000, i =>
    {
        var getWeatherUri = new Uri("https://localhost:44341/weatherforecast");

        MediaTypeWithQualityHeaderValue requestHeader = new MediaTypeWithQualityHeaderValue("application/json");
        var client = new HttpClient();
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(requestHeader);
        var response = client.GetAsync(getWeatherUri.AbsoluteUri).Result;
        if (!response.IsSuccessStatusCode)
        {
            throw new Exception($"{response.StatusCode}: {response.RequestMessage} | {response.ReasonPhrase}");
        }
    });
}

Further technical details

• Exception details: System.ObjectDisposedException HResult=0x80131622 Message=IFeatureCollection has been disposed. Object name: ‘Collection’. Source=Microsoft.AspNetCore.Http.Features StackTrace: at Microsoft.AspNetCore.Http.Features.FeatureReferences`1.ThrowContextDisposed() in /_/src/Http/Http.Features/src/FeatureReferences.cs:line 120

• ASP.NET Core version - 3.1.0

• Output of dotnet --info: dotnetInfo.txt

• The IDE is VS2019 Version 16.4.1

[Tratcher]

I checked with MVC and controllers are not supported as singletons. They have request state, so even if you didn’t hit issues like this, you’d still have concurrency problems.

[Jasdo]

@Tratcher, @anurse Thank you for your help!