GitHub-hosted runner shuts down in 3 attempts (UserCancelled)

[luiguiHerrera]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

ARC (Actions Runner Controller)

Discussion Details

Summary

Three attempts of the same GitHub Actions workflow failed because the GitHub-hosted runner unexpectedly shut down at virtually the same point, without any test failures.

Repository: luiguiHerrera/Luiguiherrera-web

Workflow run: https://github.com/luiguiHerrera/Luiguiherrera-web/actions/runs/42536568040

Commit: 83d304321a2937713942d908c811d40c15e59847

Affected attempts

Attempt | Job ID | Duration -- | -- | -- 1 | 128902060583 | 11m 16s 2 | 128907108347 | 10m 25s 3 | 129200312849 | 12m 38s

Attempt 3 was executed with debug logging enabled.

Observed behavior

All three attempts:

• Completed 116 Python tests successfully, with no FAIL or ERROR results.

• Stopped immediately after test_wrong_or_extra_parent_rejected passed.

• Interrupted the remaining tests and all subsequent workflow steps.

• Ended with the workflow conclusion failure.

The third attempt's diagnostic logs contain:

Runner will be shutdown for UserCancelled

The process subsequently exited with code 143.

The runner had successfully renewed its job lease shortly before the interruption.

Configuration

• GitHub-hosted Ubuntu runners.

• Runner version: 2.338.2.

• Job timeout: 40 minutes.

• No step-specific timeout.

• No concurrency cancellation configuration.

• No explicit cancellation request identified.

The interruptions occurred well before the configured job timeout.

Investigation performed

The next test class, ZodSecurityTests, has an initialization step that creates temporary Git fixtures.

Its setUpClass() method was executed independently on macOS and completed successfully in 13.34 seconds, with a measured Python memory peak of 447.6 MiB.

This does not reproduce the hosted Linux environment. Resource exhaustion remains unconfirmed.

The UserCancelled diagnostic indicates the runner's internal shutdown category, but does not establish that a user manually canceled the workflow.

Questions

1. What might cause a GitHub-hosted runner to receive a UserCancelled shutdown signal at nearly the same point across three attempts?

2. Is there a known runner orchestration or resource-management issue that could explain this behavior?

3. What additional diagnostic evidence would help identify the source of the shutdown?

4. Is there a way to distinguish an infrastructure-initiated shutdown from an external cancellation request?

The root cause remains unknown. We have preserved the debug logs and are avoiding further retries or code changes without evidence of a specific cause.

Any guidance from GitHub engineers or community members would be appreciated.

[github-actions[bot]]

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