Exception thrown inside HostedService is not being captured by OTEL unless it is placed as part of the error logging

[jundayin]

My worker application hosts a HostedService and it processes workflow jobs in the background. Normally it tracks logging as expected, but I do notice that in case of exception thrown OTEL does not automatically capture it as it does for foreground api request.

Is it a bug or by design? I can workaround that by asking my colleagues to include the exception object in logging, but that's error prone and counterintuitive. Everyone can make mistake and miss it.

A small repro, this is just for demonstrating my problem.

public class SampleHostedService : IHostedService
{
    private readonly ILogger<SampleHostedService> logger;
    
    private readonly ActivitySource activitySource = new ActivitySource(Constants.WorkerActivitySourceName);

    public SampleHostedService(
        ILogger<SampleHostedService> logger
    )
    {
        this.logger = logger;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        this.logger.LogTrace("App is starting");
        Task.Run(async () =>
        {
            int a = 0;
            while (this.run)
            {
                using (var activity = activitySource.StartActivity())
                {
                    if (a > 3)
                    {
                        var exception = new Exception("adssads");
                       // logger.LogError(exception,"asdsadsad"); // OTEL only see error log if I uncomment this line of code
                        throw exception; // OTEL does not show a log upon this failure
                    }
                    a++;
                    await Task.Delay(TimeSpan.FromSeconds(5));
                }
            }
        });

        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        this.run = false;
        return Task.CompletedTask;
    }
}

Here is the setup

OpenTelemetryBuilder = services
    .AddOpenTelemetry()
    .WithTracing(builder =>
    {
        builder
            .AddSource("Telemetry.Samples.AspNetCore.Worker")
            .AddConsoleExporter();
    })
    .WithLogging(builder =>
    {
        builder.AddConsoleExporter();
    });
services.AddHostedService<SampleHostedService>();

[jundayin]

Close this thread as I decided to move it to Issue #6152