netcore not logging to console

问题

I have a simple test project to experiment with logging with NetCore 2.0 using the Microsoft Logging Extensions package.

The problem I'm having is that when I run my app the very first time, it logs informational messages as expected. The weird behavior I'm having though is that subsequent runs won't produce any messages at all.

My project targets the Net Core 2.0 framework, and has the following NuGet packages installed:

• Microsoft.Extensions.Logging
• Microsoft.Extensions.Logging.Abstractions
• Microsoft.Extensions.Logging.Console
• Microsoft.Extensions.Logging.Debug

Below is my sample code I'm trying to get logging working with:

using System;

namespace LoggingNetCore2
{
    using Microsoft.Extensions.Logging;

    class Program
    {
        static void Main(string[] args)
        {
            var loggerFactory = new LoggerFactory();
            loggerFactory.AddConsole();
            loggerFactory.AddDebug(); // <-- why is this needed for console logging?

            var logger = loggerFactory.CreateLogger(typeof(Program));
            logger.LogInformation("Hello, World!");
            logger.LogTrace("trace");
            logger.LogDebug("debug");
            logger.LogWarning("warning");
            logger.LogCritical("critical");
            logger.LogError("errrrr");

            //using (logger.BeginScope("MyMessages"))
            //{
            //    logger.LogInformation("Beginning Operation...");
            //    logger.LogInformation("Doing something cool... please wait.");
            //    logger.LogInformation("Completed successfully.");
            //}
        }
    }
}

I get no output on the console window when I run the above. Any ideas that spring to mind on what could be going on?

Things I've tried:

• Added the Microsoft.Extensions.Logging.Abstractions package, as I vaguely remember needing to do that in NetCore 1.0 apps in the past.
• Uninstalled / reinstalled the above packages.
• I've even tried running the app from the command line via the dotnet.exe command, but to no avail.
• If I downgrade to NetCore framework 1.1 (and the NuGet packages to the 1.1 versions), things work as expected.

Edit: I got logs showing now in the console window if I add the debug logging provider into the mix.

In a NetCore 1.x app, simply adding the console provider was enough.

Edit #2: Turns out the console logging provider doesn't immediately flush the messages to the console like it did in the net-core-1.x versions. It appears to run on a different thread. See this web page for info: https://github.com/aspnet/Logging/issues/631

回答1:

@ajawad987, you're right. The Dispose() works.

public class Program
{
    public static void Main(string[] args)
    {
        var services = new ServiceCollection()
            .AddLogging(config => config.AddConsole())
            .BuildServiceProvider();

        services.GetRequiredService<ILogger<Program>>()
            .LogCritical("Hello");

        ((IDisposable) services)?.Dispose();
    }
}

来源：https://stackoverflow.com/questions/46187323/netcore-not-logging-to-console