[mono] `System.Formats.Nrbf.Tests.EdgeCaseTests.CanReadArrayOfAnySize` times out on x64 Release Mono library legs

[vitek-karas]

Related runtime issues: #108515, #110285, #125994
Related fix attempts: #126006, #126189
Suggested labels: Known Build Error, test-failure, arch-x64, area-Codegen-JIT-mono, area-System.Formats.Nrbf, untriaged

Build Information

Build: 20260405.1, 20260405.15, 20260406.2, 20260406.53, 20260407.4, 20260407.63
Build error leg or test failing: System.Formats.Nrbf.Tests.WorkItemExecution / System.Formats.Nrbf.Tests.EdgeCaseTests.CanReadArrayOfAnySize
Affected CI jobs: osx-x64 Release Mono_MiniJIT_LibrariesTests, linux-x64 Release Mono_MiniJIT_LibrariesTests, linux-x64 Release Mono_Interpreter_LibrariesTests

Error Message

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

{
  "ErrorMessage": [
    "CanReadArrayOfAnySize",
    "Executor timed out after 900 seconds and was killed"
  ],
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Summary

This is a recurrence of the existing System.Formats.Nrbf.Tests timeout history, not a brand-new failure mode.

Representative macOS and Linux Helix logs for the April 2026 bucket show the same pattern:

Starting:    System.Formats.Nrbf.Tests
System.Formats.Nrbf.Tests: [Long Running Test] 'System.Formats.Nrbf.Tests.EdgeCaseTests.CanReadArrayOfAnySize'
[EXECUTION TIMED OUT]
Exit Code:-3
Executor timed out after 900 seconds and was killed

Relevant prior tracking:

1. dotnet/runtime#110285 captured the older broad KBE for System.Formats.Nrbf.Tests timeouts.
2. dotnet/runtime#108515 narrowed the pattern to Mono x64 library legs, especially linux_x64_release_mono_minijit_librariestests and sometimes linux_x64_release_mono_interpreter_librariestests.
3. dotnet/runtime#125994 named the exact test now showing up again in Helix logs: System.Formats.Nrbf.Tests.EdgeCaseTests.CanReadArrayOfAnySize.

Relevant fix attempts:

1. dotnet/runtime#126006 tried to fix the timeout by skipping the 2 GB Array.MaxLength case on non-release runtimes.
2. dotnet/runtime#126189 was a follow-up because #126006 was incomplete; it tightened the condition so the large-case test requires not just a release runtime but also an optimized library.

Both PRs merged on 2026-03-27, before these 2026-04-05 through 2026-04-07 failures. That makes this bucket best understood as a recurrence / incomplete fix on Mono release jobs, not a fresh product regression.

The likely hot path remains src/libraries/System.Formats.Nrbf/tests/EdgeCaseTests.cs, specifically CanReadArrayOfAnySize(int length) with the InlineData(2147483591) (Array.MaxLength) case. A practical next step is to reopen or extend the Mono tracking in #108515 and cross-link #125994, #126006, and #126189.

Note

This issue was filed with the assistance of GitHub Copilot.

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Summary

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