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Unit-test executable intermittently exits 139 in native thread-static initialization on macOS arm64 #7434
Description
Summary
The net10.0 unit-test executable exited with code 139 before reporting any tests on macOS arm64. The macOS crash report identifies a native .NET runtime null-address fault in MethodTable::CheckRunClassInitThrowing() called by GetThreadStaticsByIndex. A subsequent run of the same binaries passed; this report preserves the intermittent failure for investigation.
Reproduction
Observed once while validating #7417 (head 993e845ad05dc3acd97523cdbb5eecefef6d2866 with the pending scope-cleanup and retry-handler fixes):
dotnet test --project tests/TUnit.UnitTests --framework net10.0A targeted TUnit.TestProject build was running concurrently. After that build finished, dotnet test --project tests/TUnit.UnitTests --framework net10.0 --no-build passed with 699 tests and 3 skips. Reproduction is intermittent; concurrent builds have not been established as the cause.
Expected and actual
Expected: tests run and report managed failures if present.
Actual: zero tests reported, exit 139, with a native EXC_BAD_ACCESS / SIGSEGV at address 0x20 on a .NET TP Worker thread. Top native frames:
MethodTable::CheckRunClassInitThrowing()
GetThreadStaticsByIndex + 100
Environment
- SDK: 10.0.403 (the version selected by global.json)
- Microsoft.NETCore.App: 10.0.14
- macOS: 27.2 (26B123), arm64
Please investigate the intermittent native crash, preserving a runtime dump if it recurs.
Activity
thomhurst commentedon Nov 3, 2026
Audited against main
d87516cb9cand the linked #7417 report. No later reproduction, runtime diagnosis, or fix is recorded, and the same-binary pass does not establish that the crash is fixed. Keep this investigation open; capture a runtime dump if it recurs, as requested. No dependency on #7417 is needed because a native runtime failure has not been attributed to that change.thomhurst commentedon Nov 5, 2026
Investigated current main
08f2aca66eon macOS arm64 with SDK 10.0.403 / runtime 10.0.14. The unit suite passed (935 total: 932 succeeded, 3 skipped) with crash capture enabled; no recurrence was observed.The archived original macOS report from 2026-11-03 01:03:55 confirms SIGSEGV at address 0x20 in
MethodTable::CheckRunClassInitThrowing()/GetThreadStaticsByIndex + 100. Recent local reports are Native AOT SIGABRT failures with different stacks and are not evidence of this crash recurring. The similar upstream report dotnet/runtime#132691 was closed as resolved by 10.0.12; this report uses 10.0.14, so matching stacks do not establish the same cause.PR #7659 adds macOS CI heap crash-dump capture and seven-day artifact retention, plus local reproduction/capture instructions. A standalone FailFast probe verified that these settings produce a dump (370,430,104 bytes) while retaining failure exit 134; the synthetic dump was then deleted. The PR intentionally does not close this investigation: there is no evidence yet of a TUnit fix or an attributable upstream defect. If the exit-139 fault recurs, retain the new dump, exact runtime/commit and native crash report before rerunning; use that evidence to establish a minimal reproduction and root cause.
Encrypt credential-bearing crash dumps for #7434
Clarify crash capture process scope for #7434
Capture macOS native runtime crashes for diagnosis (#7659)