wasi-shims: re-arm the timer pollable's sleep; chunk below the setTimeout ceiling - #78
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…eout ceiling Pollable.timer cached its wake promise forever (armed ??= with no reset). ready() consults the clock, so any EARLY-firing sleep left the cached promise permanently settled while ready() stayed false — and block()/poll()'s re-check loops (await an already-settled promise, re-check, repeat) degenerate to a hot microtask spin that starves the event loop: the livelock class the parking kernel exists to kill. The severe trigger is the engine's setTimeout ceiling: delays above 2^31-1 ms are clamped to ~0 (node/Deno warn and fire at 1 ms), so any deadline past ~24.8 days — far-future timeouts, u64 sentinels — spun hot for its whole duration. Ordinary timer slop (early by a tick) caused the same spin briefly. Fix: one in-flight sleep shared by concurrent waiters, re-armed after every settle with the delta recomputed, each sleep capped at the ceiling (TIMER_CHUNK_MAX_MS) — far deadlines sleep in chunks and re-check the clock at each chunk end. Pins (both fail-on-pre-fix, verified by stash/unstash): a frozen-clock early fire must yield a fresh PENDING promise from the next wait(); a +60-day deadline's wait is still parked 30 ms in (pre-fix the clamp settled it at ~1 ms). sanitizeOps off for exactly these two: the re-armed sleeps outlive the tests by design (nothing in the WIT surface cancels a timer). Gates: test-wasi-shims 52/0 (+2), websocket-conformance 55/55 at baseline wall time.
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Review finding on #71:
Pollable.timercached its wake promise forever (armed ??=, never reset).ready()consults the clock, so an early-firing sleep left the cached promise permanently settled whileready()stayed false —block()/poll()'s re-check loops then await an already-settled promise in a tight cycle: a hot microtask spin that starves the event loop, i.e. the livelock class the parking kernel exists to kill.Severe trigger: the engine setTimeout ceiling — delays > 2^31−1 ms clamp to ~0 (node/Deno warn, fire at 1 ms; verified empirically) — so any deadline past ~24.8 days (far-future timeouts, u64 sentinels) spun hot for its whole duration. Ordinary timer slop (early by a tick) caused the same spin briefly.
Fix: one in-flight sleep shared by concurrent waiters (promise-swap contract unchanged), re-armed after every settle with the delta recomputed; each sleep capped at
TIMER_CHUNK_MAX_MS(2^31−1) so far deadlines sleep in ceiling-sized chunks, re-checking the clock at each chunk end.Pins (both fail-on-pre-fix, verified via stash/unstash): frozen-clock early fire → next
wait()must be a fresh pending promise; +60-day deadline → wait still parked 30 ms in (pre-fix: settled at ~1 ms).sanitizeOps: falseon exactly these two — the re-armed sleeps outlive the tests by design (the WIT surface has no timer cancel).Gates:
just test-wasi-shims52/0 (+2 new),just websocket-conformance55/55 at baseline wall time (14.4 s).