The repo’s CI doesn’t run tests on macOS, and there’s no regression test that would fail if Socket.Select blocks forever in the poll loop. Consider adding a regression test that exercises Cleanup(block: false) under the same conditions as #1040 and asserts it completes within a bounded time (and/or add a macOS CI job so the test actually runs on the affected platform).

Originally posted by @copilot-pull-request-reviewer in #1142 (comment)