[rzikm]

The HTTP/2 TimeInQueue_RecordedForNewConnectionsOnly test assumes that completing the first response makes its connection immediately available to subsequent requests. The pool can signal the first waiter before publishing the connection, so later sequential requests can legitimately queue on that same connection and produce two or three measurements. Queue duration measures waiting for an available connection, not just connection establishment.

This test-only change waits for publication before testing reuse. A scoped private EventSource listener correlates the first request URI with its pool/connection identifiers and waits for that connection's publication, including when publication precedes request correlation. The callback does not block, and the wait has a timeout. The first measurement's duration and tags are checked, and the final expected count stays 1. Production behavior, metric tags, and HTTP/1.1 and HTTP/3 handling are unchanged.

The intentional maintenance dependency is on the private Sending request: and Put HTTP2 connection in pool. trace messages. Related to #122522; this does not claim to resolve its HTTP/3 reports or prove the schedule of every historical CI failure.

Validation

Windows x64, Debug libraries and Release runtime:

• Baseline clr+libs build passed.
• An artifact-only forced-scheduling probe reproduced Actual 2 and Actual 3 against the original test for both HttpClient and HttpMessageInvoker. The corrected test passed six controls covering delayed publication, publication before correlation, and unrelated-Meter isolation. The probe is not part of this PR.
• All nine metrics fixtures: 298 passed, 2 expected skips.
• Existing saturated HTTP/2 connection queue-telemetry control: 1 passed.
• NativeAOT HTTP/2 metrics fixtures: 72 passed, 4 existing skips; both changed test variants passed.

Linux/musl was not run locally. No clean full-library result is claimed: an accidentally unfiltered NativeAOT invocation was stopped after failures outside the target fixtures; the final explicitly filtered invocation passed.

Note

This change and description were generated with GitHub Copilot.

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[MihaZupan]

Thanks