[ci-scan] Test failure: Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTests.GCRefStress_AllVerificationsPass (Windows x86 EventSource) #135085

Description

Windows x86 cDAC GC-reference stress intermittently misses roots in System.RuntimeType.SplitName, GetNestedType, and EventSource initialization. The distinctive signature is cDAC=7 RT=47 frames=12 (match=5 mismatch=7 known_nie=0).

Reproduction Steps

Observed in the runtime-diagnostics pipeline's windows-x86 release CdacStressTest job. The same signature appears in main build 1591981, queued September 11 at commit 3898c7135c4dc861e00f49285d0c275f69e2e6c5, and PR build 1620305. No deterministic local reproduction has been established.

Expected behavior

The cDAC and native runtime report matching GC-reference sets at each stress verification point.

Actual behavior

Seven frames omit roots in the cDAC result. The full failing stack summary is included under Error Details.

Regression?

Pre-existing on main at least since September 11, before PR #135055. Recent main runs also pass this job; the underlying cause has not been identified.

Known Workarounds

None established.

Configuration

Windows x86, Release, cDAC GC-reference stress. The Helix queue uses an x64 Windows host, but the failing runtime/test configuration is x86.

Other information

The signature occurs in BasicAlloc, DeepStack, ExceptionHandling, and NotYetLoadedArgType in build 1620305, and DeepStack, Generics, and CallSignatures in the earlier main build. This issue covers only the EventSource/root-count signature below, not every failure of the stress test or the separate PrestubMethodFrame mismatch in the same PR run.

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1620305
Build error leg or test failing: windows-x86 release CdacStressTest - Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTests.GCRefStress_AllVerificationsPass
Pull request: #135055

PR failure log: https://helix.dot.net/api/2019-06-17/jobs/eb8ed009-397d-4232-80ff-636980b1e497/workitems/CdacStressTests/console
Main failure log: https://helix.dot.net/api/2019-06-17/jobs/bb870b06-ca01-4182-83b1-870d2b259869/workitems/CdacStressTests/console

Error Details

Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTests.GCRefStress_AllVerificationsPass(debuggee: Debuggee { Name = BasicAlloc, WindowsOnly = False, SkipGCRefs = False }) [FAIL]
GCREFS stress test 'BasicAlloc' had 2 failure(s) and 0 known issue(s) out of 4988 verifications.

[FAIL] Thread=0x1970 IP=0x73C1E08C cDAC=7 RT=47 frames=12 (match=5 mismatch=7 known_nie=0)
Stack trace:
  #0 <frame ExternalMethodFrame 0xb7d9c0> (cDAC=1 RT=1)
  #1 <other 0xb7de9c> (cDAC=1 RT=1)
  #2 <other 0xb7e960> (cDAC=3 RT=3)
  #3 <other 0xb7f00c> (cDAC=1 RT=1)
  #4 System.RuntimeType.SplitName(System.String, System.String ByRef, System.String ByRef) (cDAC=0 RT=1) <-- MISMATCH
  #5 System.RuntimeType.GetNestedType(System.String, System.Reflection.BindingFlags) (cDAC=0 RT=3) <-- MISMATCH
  #6 System.Diagnostics.Tracing.EventSource.Initialize(System.Guid, System.String, System.String[]) (cDAC=0 RT=7) <-- MISMATCH
  #7 System.Diagnostics.Tracing.EventSource.DoCommand(System.Diagnostics.Tracing.EventCommandEventArgs) (cDAC=0 RT=4) <-- MISMATCH
  #8 System.Diagnostics.Tracing.EventSource.EnsureDescriptorsInitialized() (cDAC=0 RT=5) <-- MISMATCH
  #9 System.Diagnostics.Tracing.EventSource.InitializeDefaultEventSources() (cDAC=1 RT=1)
  #10 System.Diagnostics.Tracing.EventSource+EventSourceHelpers.CreateManifestAndDescriptors(System.Type, System.String, System.Diagnostics.Tracing.EventSource, System.Diagnostics.Tracing.EventManifestOptions) (cDAC=0 RT=19) <-- MISMATCH
  #11 System.Diagnostics.Tracing.NativeRuntimeEventSource..cctor() (cDAC=0 RT=1) <-- MISMATCH

Error Message

{
  "ErrorMessage": "cDAC=7 RT=47 frames=12 (match=5 mismatch=7 known_nie=0)",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Report

Summary