Failed test: GC/API/GC/GetGeneration/GetGeneration.dll

[JulieLeeMSFT]

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1531411
Build error leg or test failing: GC/API/GC/GetGeneration/GetGeneration.dll

• Massive failures in many configs

14:46:12.949 Running test: GC/API/GC/GetGeneration/GetGeneration.dll
0 0
ObjectTest Failed!
0 0
arrayTest Failed!
failTest Passed!

Test for GetGeneration() FAILED!
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual:   1
   at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
   at Xunit.Assert.Equal[T](T expected, T actual) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 36
   at Program.<<Main>$>g__TestExecutor28|0_29(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "Failed test: GC/API/GC/GetGeneration/GetGeneration.dll",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1531411
Error message validated: [Failed test: GC/API/GC/GetGeneration/GetGeneration.dll]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 7/29/2026 5:40:38 PM UTC

Report

Build	Repository	Test	Pull Request
1538649	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll	#131754
1537295	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll
1536715	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll
1534710	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll
1533324	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll
1533254	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll	#131590
1532391	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll	#131027
1531411	dotnet/runtime	GC/API/GC/GetGeneration/GetGeneration.dll

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
2	8	8

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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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[JulieLeeMSFT]

GC tests are failing in runtime-interpreter. cc @davidwrighton, if it's related to your recent change.

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[janvorli]

This test has been always failing on my local machine. I am actually surprised it wasn't failing in the CI bewfore.

[janvorli]

The test expects that a generation of a freshly created object will grow after GC.Collect() call and with interpreter it doesn't. I have verified that the local holding the object is reported to GC. It is reported as pinned, so I guess that might cause a demotion. I am looking into it to make sure it is not a bug.

[janvorli]

I've debugged it. It is an interpreter incompatibility. The thing is that when interpreted code reports the local that we check the generation for, the GC info marks that local intentionally as pinned. GC then due to this decides to demote the object back to generation 0. But the test expects that after a GC.Collect, it would get higher generation.