Aspnetcore: .NET Core Worker not call ExecuteTask

Created on 31 Mar 2019 · 11Comments · Source: dotnet/aspnetcore

Describe the bug

I have create a worker using "dotnet new worker" but using code bellow no events are written to EventLog:

program.cs
````csharp
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.EventLog;

namespace CoreWindowsService
{
public class Program
{
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .UseServiceBaseLifetime()
            .ConfigureLogging(loggerFactory => loggerFactory
                .AddEventLog(new EventLogSettings() {SourceName = "CoreWindowsService"}))
            .ConfigureServices(services =>
            {
                services.AddHostedService<Worker>();
            });
}

}
````

worker.cs
````csharp
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace CoreWindowsService
{
public class Worker : BackgroundService
{
private readonly ILogger _logger;

    public Worker(ILogger<Worker> logger)
    {
        _logger = logger;
    }

    public override async Task StartAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation($"Iniciado: {DateTime.Now}");
        await Task.CompletedTask;
    }

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation($"Parado: {DateTime.Now}");
        await Task.CompletedTask;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            _logger.LogInformation($"Executando: {DateTime.Now}");
            await Task.Delay(1000, stoppingToken);
        }
    }
}

}

````
Attaching debug session to installed service, nothing happen!

Docs Done area-hosting

Source

carloscds

All 11 comments

I have discover that problem is StartAsync() and StopAsync() methods. This happen because I used override on methods, change to:

````csharp
public async Task StartAsync(CancellationToken cancellationToken)
{
_logger.LogInformation($"Iniciado: {DateTime.Now}");
await Task.CompletedTask;
}

    public async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation($"Parado: {DateTime.Now}");
        await Task.CompletedTask;
    }

````
Works fine!

But I receive an alert about "override"!

carloscds on 31 Mar 2019

👍1

Yes this is because you need to call the base in StartAsync and StopAsync (which I agree is a bit unclear). Changing this wild be a breaking change at this point so I’m not sure how much we’d be willing to do here

davidfowl on 31 Mar 2019

@davidfowl Maybe you can change sample at blog post including Start and Stop calls!

carloscds on 1 Apr 2019

@davidfowl Now it's working:

````csharp
public override async Task StartAsync(CancellationToken cancellationToken)
{
_logger.LogInformation($"Iniciado: {DateTime.Now}");
await base.StartAsync(cancellationToken);
}

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation($"Parado: {DateTime.Now}");
        await base.StopAsync(cancellationToken);
    }

````

carloscds on 1 Apr 2019

@carloscds - should this issue be closed? Or do you have any further questions?

Eilon on 1 Apr 2019

Do you mean my blog posts about running as a Windows Service? I am happy with that.

@Eilon I think we add the doc label to this to make sure we have a note in any official docs about this scenario. I'll call it out in an up-coming blog post to help anyone else who gets caught by it.