[NOMERGE] [HTTP] Metrics logging

[ManickaP]

Additional logging to investigate #122522

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[Copilot]

Pull request overview

This PR adds extra diagnostics to the System.Net.Http metrics functional tests to help investigate intermittent failures in HttpMetricsTest_Http20.TimeInQueue_RecordedForNewConnectionsOnly (#122522).

Changes:

• Augments InstrumentRecorder<T> to attach stack traces to recorded measurements and adds a Clear() helper.
• Modifies TimeInQueue_RecordedForNewConnectionsOnly to repeatedly run the scenario and dump stack traces when unexpected extra measurements are recorded.
• Adds a new using TestUtilities; (currently only referenced by a commented-out line).

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (4)

src/libraries/System.Net.Http/tests/FunctionalTests/MetricsTest.cs:216

• InstrumentRecorder<T> now unconditionally captures Environment.StackTrace and adds it as a tag for every recorded measurement. This is very allocation-heavy (full stack trace string per measurement) and changes the tag set for all metrics tests in this file, which can significantly slow / flake the suite. Consider gating stack capture behind an opt-in switch/environment variable so the default path preserves the original lightweight behavior.

            private void OnMeasurementRecorded(Instrument instrument, T measurement, ReadOnlySpan<KeyValuePair<string, object?>> tags, object? state)
            {
                KeyValuePair<string, object?>[] newTags = [..tags, new ("stack", Environment.StackTrace)];
                _values.Enqueue(new Measurement<T>(measurement, newTags));
                MeasurementRecorded?.Invoke();

src/libraries/System.Net.Http/tests/FunctionalTests/MetricsTest.cs:941

• Dumping full stack traces via Console.WriteLine when the assertion is about to fail can produce extremely large test output and slow down Helix runs. Prefer writing to ITestOutputHelper and gating the diagnostic output behind an opt-in switch so normal CI runs stay quiet.

                if (timeInQueueRecorder.MeasurementCount > 1)
                {
                    foreach (var v in timeInQueueRecorder.GetMeasurements())
                    {
                        foreach (var t in v.Tags)
                        {
                            if (t.Key == "stack")
                            {
                                Console.WriteLine(t.Value);
                            }
                        }
                    }
                }

src/libraries/System.Net.Http/tests/FunctionalTests/MetricsTest.cs:918

• The test now runs an inner loop of 3,000 client/server sessions and 5 requests each. This is likely to cause long runtimes/timeouts in CI and makes the test behavior depend on load/timing. If this is only for diagnostics, please gate the iteration count behind an environment variable (defaulting to 1) and fix the brace/indentation style.

            using HttpMessageInvoker client = CreateHttpMessageInvoker();
            using InstrumentRecorder<double> timeInQueueRecorder = SetupInstrumentRecorder<double>(InstrumentNames.TimeInQueue);
            for (int ii = 0; ii < 3_000; ii++) {
            const int RequestCount = 5;
            timeInQueueRecorder.Clear();

src/libraries/System.Net.Http/tests/FunctionalTests/MetricsTest.cs:285

• Applying [Collection(nameof(DisableParallelization))] to the shared HttpMetricsTest base class forces all derived metrics test classes in this file to run serially, which can substantially increase CI wall time and may hide concurrency-related issues. If only specific tests are flaky, it’s better to scope DisableParallelization to those specific test classes.

    [Collection(nameof(DisableParallelization))]