Console logging doesn't work unless there's a delay

[kjpgit]

using System.Text;
using System.Diagnostics;

 using var loggerFactory = LoggerFactory.Create(builder =>
        {
            builder
                .AddFilter("Microsoft", LogLevel.Warning)
                .AddFilter("System", LogLevel.Warning)
                .AddConsole();
        });

ILogger logger = loggerFactory.CreateLogger<Program>();
logger.LogInformation("Example log message");

//await Task.Delay(100);

Environment.Exit(10);

The above does not print anything unless you uncomment the delay. I wasted an hour of time trying to figure out why logging wasn't working. A console does not buffer output. What happens if my process crashes and the last few log lines are lost?

For the record, I'm just making a .net console app that would be running as a systemd service, and systemd would capture the stdout. No reason to delay the output.

[kjpgit]

The reason I figured it out: https://stackoverflow.com/questions/50221983/cant-get-console-logging-to-work-in-net-core-2-0

[WeihanLi]

Think it's by design and maybe the issue should be transferred to dotnet/runtime

• https://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.Logging.Console/src/ConsoleLogger.cs
• https://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.Logging.Console/src/ConsoleLoggerProcessor.cs

[baronfel]

I'd agree with that: Environment.Exit per its docs doesn't wait for thread to finish:

Exit terminates an application immediately, even if other threads are running. If the return statement is called in the application entry point, it causes an application to terminate only after all foreground threads have terminated.

[kjpgit]

You can transfer the issue if it's appropriate. My question is, is it documented that the console logger buffers / delays the output? Is there a way to turn it off? What are the failure modes when the buffer grows?

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Issue Details

---

using System.Text;
using System.Diagnostics;

 using var loggerFactory = LoggerFactory.Create(builder =>
        {
            builder
                .AddFilter("Microsoft", LogLevel.Warning)
                .AddFilter("System", LogLevel.Warning)
                .AddConsole();
        });

ILogger logger = loggerFactory.CreateLogger<Program>();
logger.LogInformation("Example log message");

//await Task.Delay(100);

Environment.Exit(10);

The above does not print anything unless you uncomment the delay. I wasted an hour of time trying to figure out why logging wasn't working. A console does not buffer output. What happens if my process crashes and the last few log lines are lost?

For the record, I'm just making a .net console app that would be running as a systemd service, and systemd would capture the stdout. No reason to delay the output.

Author:	kjpgit
Assignees:	-
Labels:	untriaged, area-Extensions-Logging, Area-NetSDK
Milestone:	-

[maryamariyan]

That's by design. Keeping open and up for grabs in the dotnet-api-docs to track adding to docs.