Blazor - rendering metrics and tracing

[pavelsavara]

Better rendering metrics

aspnetcore.components.rendering.batch.duration - Duration of rendering batch.
aspnetcore.components.rendering.batch.exception - Total number of exceptions during batch rendering.
aspnetcore.components.rendering.diff.duration - Duration of rendering component HTML diff.
aspnetcore.components.event.asynchronous.duration - Duration of processing browser event asynchronously.
aspnetcore.components.event.synchronous.duration - Duration of processing browser event synchronously.
aspnetcore.components.parameters.asynchronous.duration - Duration of processing component parameters asynchronously.
aspnetcore.components.parameters.synchronous.duration - Duration of processing component parameters synchronously.
aspnetcore.components.navigation.count - Total number of route changes.

builder.Services.ConfigureOpenTelemetryMeterProvider(meterProvider =>
{
    meterProvider.AddMeter("Microsoft.AspNetCore.Components.Rendering");
    meterProvider.AddMeter("Microsoft.AspNetCore.Components.Server.Circuits");
});

Blazor activity tracing

• new activity source Microsoft.AspNetCore.Components.Rendering

builder.Services.ConfigureOpenTelemetryTracerProvider(tracerProvider =>
{
    tracerProvider.AddSource("Microsoft.AspNetCore.Components.Rendering");
    //tracerProvider.AddSource("Microsoft.AspNetCore.SignalR.Server");
});

Feedback

• always expect the IMeterFactory to be available in DI
• make buckets different size per feedback
• optimize work with tags
• make metrics in seconds per feedback
• unit test delay feedback

TODO - Metrics need to be documented at https://learn.microsoft.com/en-us/aspnet/core/log-mon/metrics/built-in

Contributes to #53613
Contributes to #29846
Feedback for #61516

[JamesNK]

You're adding a lot of metrics here. I think you should do some performance testing. There is performance overhead of metrics - they require some synronization when incrementing counters and recording values.

Having many low level metrics could cause performance issues.