[ci-scan] Test failure: AsyncProfilerTests.RuntimeAsync_ConfigureAwaitFalse on runtime-libraries-interpreter

[github-actions]

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1479255
Build error leg or test failing: linux-x64 Release - System.Threading.Tasks.Tests

Error Details

AsyncProfilerTests.RuntimeAsync_ConfigureAwaitFalse fails on the runtime-libraries-interpreter pipeline (def 330) on linux-x64. The test expects the async profiler to emit a RuntimeAsync_ConfigureAwaitFalse_Leaf_Marker event, but only RuntimeAsync_ConfigureAwaitFalse_Marker is present in the collection.

System.Threading.Tasks.Tests.AsyncProfilerTests.RuntimeAsync_ConfigureAwaitFalse [FAIL]
      Assert.Contains() Failure: Item not found in collection
      Collection: ["RuntimeAsync_ConfigureAwaitFalse_Marker"]
      Not found:  "RuntimeAsync_ConfigureAwaitFalse_Leaf_Marker"
      ----- BEGIN ASYNC EVENTS (CSV) -----
      seq,delta,thread,event,disp,parent,frames,unwind
      0,0,9503,AsyncProfilerMetadata,0,0,0,0
      1,7600,9503,ResetAsyncThreadContext,0,0,0,0
      2,9800,9503,CreateRuntimeAsyncContext,733,731,0,0
      3,9801,9503,CreateRuntimeAsyncCallstack,733,731,1,0

Error Message

{
  "ErrorMessage": ["AsyncProfilerTests.RuntimeAsync_ConfigureAwaitFalse", "RuntimeAsync_ConfigureAwaitFalse_Leaf_Marker"],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Impact on platforms

• runtime-libraries-interpreter (def 330) / linux-x64 Release / Helix queue: linux.x64
• Also failing on osx-arm64 Release in the same pipeline

First build it occurred

• Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1464534
• Finished: 2026-06-15T14:42:58Z
• Preceded by success: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1461427 (2026-06-12)
• 6 consecutive failures in scanned window (builds 1464534 through 1482973)
• Confirmed in follow-up: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1482973 (2026-06-26)

Duplicate search

• AsyncProfilerTests RuntimeAsync_ConfigureAwaitFalse label:"Known Build Error" — 0 results
• RuntimeAsync_ConfigureAwaitFalse in:body — 0 results
• AsyncProfilerTests ConfigureAwaitFalse is:open — 0 results
• AsyncProfilerTests is:closed label:"Known Build Error" — 0 results

No existing KBE matches this signature.

---

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Report

Build	Repository	Test	Pull Request
1485857	dotnet/runtime	System.Threading.Tasks.Tests.AsyncProfilerTests.StateMachineAsync_CallstackStressWithVaryingDepths

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	1	1

[jkotas]

cc @lateralusX

[dotnet-policy-service]

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

[github-actions]

Workflow artifact: ci-fix
Artifact kind: handoff
Linked KBE: #129920

Note

AI/Copilot-generated triage note.

This Known Build Error has no producible automated code change (reason: the failure involves how the CoreCLR interpreter handles RuntimeAsync profiler event generation — an interpreter/runtime internal that exceeds automated fix bounds), so I could not open even a best-effort PR. Looping in owners so it can be fixed forward rather than muted.

Root cause (best analysis)

AsyncProfilerTests.RuntimeAsync_ConfigureAwaitFalse fails on the runtime-libraries-interpreter pipeline (linux-x64 and osx-arm64) because the async profiler callstack resolution does not capture all nested async frame names when running under the CoreCLR interpreter.

The test calls a chain of three [RuntimeAsyncMethodGeneration(true)] methods:

• RuntimeAsync_ConfigureAwaitFalse_Marker → _Mid_Marker → _Leaf_Marker

It then expects all three method names to appear as frames in the deepest ResumeRuntimeAsyncCallstack event. Under the interpreter, only RuntimeAsync_ConfigureAwaitFalse_Marker appears:

Assert.Contains() Failure: Item not found in collection
Collection: ["RuntimeAsync_ConfigureAwaitFalse_Marker"]
Not found:  "RuntimeAsync_ConfigureAwaitFalse_Leaf_Marker"

The [RuntimeAsyncMethodGeneration(true)] attribute instructs the JIT to generate RuntimeAsync-aware code. The interpreter likely does not honor this attribute (or does not emit the corresponding profiler events for nested async frames), causing the leaf and mid method frames to be absent from the profiler callstack.

The test precondition IsRuntimeAsyncSupported checks only !IsMonoRuntime (see PlatformDetection.cs:477), which returns true for the CoreCLR interpreter — so the test runs even though the interpreter may not fully support RuntimeAsync event generation.

Evidence

• Failing build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1479255
• First failure: build 1464534 (2026-06-15T14:42:58Z)
• Last success: build 1461427 (2026-06-12)
• 6 consecutive failures through build 1482973 (2026-06-26)
• Test source: src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/System.Runtime.CompilerServices/AsyncProfilerV2Tests.cs:1864
• Platform detection: src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs:477 — IsRuntimeAsyncSupported => !IsMonoRuntime
• Suspected regressing change: none identified — no changes to the test file, interpreter, or profiler code were found in the regression window (June 12–15). The regression may stem from a runtime or interpreter change not directly touching these files.

Suggested reviewers / area contacts

• Area lead (area-Diagnostics-coreclr): @steveisok
• Area owners: @tommcdon, @dotnet/dotnet-diag
• Already cc'd by @jkotas: @lateralusX (interpreter/runtime async expert)

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