Add logging sampling documentation

[evgenyfedorov2]

Summary

Fixes #45661

---

Internal previews

📄 File	🔗 Preview link
docs/core/extensions/logging-sampling.md	Logging sampling in .NET
docs/navigate/tools-diagnostics/toc.yml	docs/navigate/tools-diagnostics/toc

[gfoidl]

For demonstration Thread.Sleep is fine.
But IMO for pedagogical reasons Task.Delay should be used, as in real-world-code Thread.Sleep shouldn't be used in the majority of the cases (blocks the thread), whereas Task.Delay is a proper alternative.

Thus as this is the "docs" the sample should show good practices.
Especially as the code change is trivial and doesn't make things more complicated.

Suggested change

	Thread.Sleep(100);
	await Task.Delay(100);

The method must be adjusted accordingly -- or use top level statements, then the compiler handles this.

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The same on other places (I don't comment on them to reduce noise)

[gfoidl]

Why not use top level statements?

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The same on other places (I don't comment on them to reduce noise)

[IEvangelist]

Agreed, top-level statements please.

[gfoidl]

Isn't this the default from the SDK?
So this could be omitted for brevity.

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The same on other places (I don't comment on them to reduce noise)

[IEvangelist]

Hi @evgenyfedorov2,

Let's get this cleaned up then have another quick look. This is awesome content, really looking forward to seeing this in docs. I'm curious, have you considered adding this to the fundamentals TOC.yml as well, so that it could be positioned under the Logging section there?

[IEvangelist]

Just so you're aware, as the author, you'll be pinged for issues with the content and expected to maintain it. If you're good with that, leave the ms.author, otherwise omit it and the team will help maintain this.

[IEvangelist]

The phrase 'Logging sampling' doesn't sound quite right. On the other hand, 'log sampling' is more commonly used and widely adopted in the industry.

Suggested change

	title: Logging sampling
	title: Log sampling

[IEvangelist]

Suggested change

	description: Learn how to fine-tune the volume of logs emitted by your application using Logging Sampling.
	description: Learn how to fine-tune the volume of logs emitted by your application using log sampling.

[IEvangelist]

Suggested change

	# Logging sampling in .NET
	# Log sampling in .NET

[IEvangelist]

Suggested change

	.NET provides logging sampling capabilities that allow you to control the volume of logs your application emits without losing important information. The following sampling strategies are available:
	.NET provides log sampling capabilities that allow you to control the volume of logs your application emits without losing important information. The following sampling strategies are available:

[IEvangelist]

Suggested change

	<PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.0" />
	<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="9.0.0" />
	<PackageReference Include="Microsoft.Extensions.Telemetry" Version="9.4.0" />
	<PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.4" />
	<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="9.0.4" />
	<PackageReference Include="Microsoft.Extensions.Telemetry" Version="9.4.0" />

[IEvangelist]

Suggested change

	<ItemGroup>
	<None Update="appsettings.json">
	<CopyToOutputDirectory>Always</CopyToOutputDirectory>
	</None>
	</ItemGroup>

[IEvangelist]

Suggested change

	// Licensed to the .NET Foundation under one or more agreements.
	// The .NET Foundation licenses this file to you under the MIT license.

[IEvangelist]

Suggested change

	internal static class Program
	{
	private static readonly ActivitySource DemoSource = new("LogSamplingTraceBased");
	public static void Main()
	{
	var hostBuilder = Host.CreateApplicationBuilder();
	hostBuilder.Logging.AddSimpleConsole(options =>
	{
	options.SingleLine = true;
	options.TimestampFormat = "hh:mm:ss";
	});
	// Add the Random probabilistic sampler to the logging pipeline.
	hostBuilder.Logging.AddTraceBasedSampler();
	var tracerProvider = Sdk.CreateTracerProviderBuilder()
	// enable Tracing sampling configured with 50% probability:
	.SetSampler(new TraceIdRatioBasedSampler(0.5))
	.AddSource("LogSamplingTraceBased")
	.AddConsoleExporter()
	.Build();
	var app = hostBuilder.Build();
	var loggerFactory = app.Services.GetRequiredService<ILoggerFactory>();
	var logger = loggerFactory.CreateLogger("SamplingDemo");
	// on average, 50% of Activities and logs will be sampled:
	for (int i = 0; i < 10; i++)
	{
	using var activity = DemoSource.StartActivity("SayHello");
	activity?.SetTag("foo", "bar");
	activity?.SetStatus(ActivityStatusCode.Ok);
	// the parent activity is sampled with 50% probability,
	// and the same sampling decision will be used for logging
	logger.NoisyMessage(i);
	}
	tracerProvider.Dispose();
	}
	}
	using ActivitySource demoSource = new("LogSamplingTraceBased");
	var hostBuilder = Host.CreateApplicationBuilder(args);
	hostBuilder.Logging.AddSimpleConsole(options =>
	{
	options.SingleLine = true;
	options.TimestampFormat = "hh:mm:ss";
	});
	// Add the Random probabilistic sampler to the logging pipeline.
	hostBuilder.Logging.AddTraceBasedSampler();
	using var tracerProvider = Sdk.CreateTracerProviderBuilder()
	// Enable Tracing sampling configured with 50% probability:
	.SetSampler(new TraceIdRatioBasedSampler(0.5))
	.AddSource("LogSamplingTraceBased")
	.AddConsoleExporter()
	.Build();
	using var app = hostBuilder.Build();
	var loggerFactory = app.Services.GetRequiredService<ILoggerFactory>();
	var logger = loggerFactory.CreateLogger("SamplingDemo");
	// On average, 50% of Activities and logs will be sampled:
	for (int i = 0; i < 10; i++)
	{
	using var activity = demoSource.StartActivity("SayHello");
	activity?.SetTag("foo", "bar");
	activity?.SetStatus(ActivityStatusCode.Ok);
	// The parent activity is sampled with 50% probability,
	// and the same sampling decision will be used for logging
	logger.NoisyMessage(i);
	}

[IEvangelist]

Suggested change

	- name: Logging Sampling
	- name: Log Sampling