System.TypeInitializationException in ActivityListener when accessing ActivitySource from a static field

[flibustier7seas]

Description

A System.TypeInitializationException may be thrown when an ActivityListener accesses an ActivitySource stored in a static field.

Reproduction Steps

[TestFixture]
public class DiagnosticsTests
{
    private static class Telemetry
    {
        public static ActivitySource MyActivitySource { get; } = new ActivitySource("MyActivitySource");
    }

    [Test]
    public void Test()
    {
        ActivitySource.AddActivityListener(new ActivityListener
        {
            ShouldListenTo = newActivitySource =>
            {
                var myActivitySource = Telemetry.MyActivitySource;

                // System.TypeInitializationException : The type initializer for 'Telemetry' threw an exception.
                //     ----> System.NullReferenceException : Object reference not set to an instance of an object.
                //     at DiagnosticsTests.Telemetry.get_MyActivitySource()
                return newActivitySource.Name == myActivitySource.Name;
            },
            Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllData,
        });

        var activity = new ActivitySource("OtherActivitySource").StartActivity();

        Assert.That(activity, Is.Null);
    }
}

Expected behavior

Accessing ActivitySource within an ActivityListener should not result in an exception.

Actual behavior

Accessing ActivitySource within an ActivityListener causes a System.TypeInitializationException with an inner NullReferenceException.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

Issue for docs: dotnet/docs#42745

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[MichalPetryka]

The ActivitySource constructor is calling your ShouldListenTo before the field is set, seems like you can't access any ActivitySources inside of a listener.

[flibustier7seas]

seems like you can't access any ActivitySources inside of a listener.

This behavior is not obvious; it might be a bug. If not, it should be documented properly.

[tarekgh]

This is not a bug. The order of the static constructor's initialization is not guaranteed and depends on the runtime. Also, we don't document every issue that can happen because of the order of the static initialization. In your code you can simply do:

            var myActivitySource = Telemetry.MyActivitySource;
            var activityListener = new ActivityListener
            {
                ShouldListenTo = newActivitySource => newActivitySource.Name == myActivitySource.Name,
                Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllData,
            };
            ActivitySource.AddActivityListener(activityListener);