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System.Tests.GCTests.LargeObjectHeapCompactionModeRoundTrips test failure #134997
Description
System.Tests.GCTests.LargeObjectHeapCompactionModeRoundTrips(value: CompactOnce) [FAIL]
Assert.Equal() Failure: Values differ
Expected: CompactOnce
Actual: Default
Stack Trace:
Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1618332
Build error leg or test failing: System.Tests.GCTests.LargeObjectHeapCompactionModeRoundTrips
Pull request: #134967
Error Message
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{
"ErrorMessage": ["LargeObjectHeapCompactionModeRoundTrips","Values differ"],
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}Known issue validation
Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1618332
Error message validated: [LargeObjectHeapCompactionModeRoundTrips Values differ]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 10/1/2026 1:23:25 AM UTC
Report
| Build | Repository | Test | Pull Request |
|---|---|---|---|
| 1620862 | dotnet/runtime | System.Tests.TimeZoneInfoTests.IsInvalidTimeTestOnLinux | |
| 1618332 | dotnet/runtime | System.Tests.GCTests.LargeObjectHeapCompactionModeRoundTrips | #134967 |
Summary
| 24-Hour Hit Count | 7-Day Hit Count | 1-Month Count |
|---|---|---|
| 0 | 0 | 2 |
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dotnet-policy-service commentedon Oct 1, 2026
Tagging subscribers to this area: @anicka-net, @dotnet/gc
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kkokosa commentedon Oct 1, 2026
This looks like a test race rather than a runtime regression.
CompactOnceis intentionally reset toDefaultby the next blocking gen-2 GC, and this test runs without isolation in a parallel assembly containing manyGC.Collectcalls. The test should either account for an intervening gen-2 GC, aslohcompactapi2.csdoes, or avoid asserting an unconditional round trip, following the precedent in #51603.