experiment: async_std::fs::File cpu.pct reliability 100x#82
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RUSAGE_CHILDREN only updates after a child exits and is waited for, so the rusage snapshot taken at signal time is identical to the original baseline. Only wall.time and instructions (Linux) are post-ready; document this accurately in README and spec.
The pipe already signals child exit via EOF when the write end closes, so racing the pipe against child.status() is unnecessary. Sequential await is simpler and removes the futures dependency entirely.
…ed CI flakiness on macOS) async_std::fs::File on macOS uses kqueue-based I/O: when the pipe event fires, the async task is rescheduled through the executor before resuming. That extra scheduling hop means proc_pidinfo is called slightly later than with spawn_blocking, which uses a dedicated OS thread that calls proc_pidinfo synchronously right after the read returns with no scheduler hop in between. On a loaded CI runner that window is large enough for the process state to change, causing proc_pidinfo to return None and the CPU subtraction to be skipped.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Experiment to measure reliability of
async_std::fs::Fileinread_one_byteon CI.Runs
ready_signal_cpu_pct_bounded100 times and reports pass/failure count.If
cpu.pct.wall.timeexceeds 100% on any run, that counts as a failure.See companion PR for
spawn_blockingcomparison.🤖 Generated with Claude Code