---
id: 49d724b4-cf00-4ac9-9bac-1b22c71f3ad8
title: m5 run_in_stdin races early-exit child (EPIPE flake)
state: closed
labels:
- dogfood
assignees: []
milestone: null
created: 2026-09-08T04:20:17Z
updated: 2026-09-08T04:33:53Z
---
m5.rs run_in_stdin does write_all(input).unwrap() on child stdin. When the child exits early (e.g. wiki put ../evil usage check before stdin read), the write races child exit -> BrokenPipe panic (~1/10 under parallel load). Fix in harness: ignore EPIPE on stdin write; exit-code/output assertions still verify behavior.