perf(noq-proto): lazily allocate remote stream slots#667
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Port of quinn-rs/quinn#2601. `StreamsState::new` used to eagerly insert `(id, None)` placeholder entries in both `send` and `recv` FxHashMaps for every remote stream id in `0..max_remote[dir]`. With `max_concurrent_*_streams = 10_000` (e.g. for MoQ relay nodes that burn through short-lived streams), hashbrown rounded each map's bucket array up to ~65K buckets, costing ~0.5-2 MB of bucket memory per Connection before any stream data was sent. Move that work into a lazy frontier-advance step at the top of each remote receive path. Remote stream state: - `id.index() >= max_remote[dir]`: not allowed - `id.index() >= next_remote[dir]`: allowed, absent from map - `id.index() < next_remote[dir]`, present: active - `id.index() < next_remote[dir]`, absent: closed RFC 9000 section 3.2 says receiving a frame for index N implicitly opens all lower indices. `ensure_remote` handles that by materializing `None` placeholders for every index in `[next_remote, id.index()]` - otherwise a late out-of-order frame for a skipped index would land on "absent from map" and get dropped as closed. Placeholders are short-lived: they get filled on first real access or removed when the stream closes, so unlike a growing "closed ids" set the map stays bounded by currently live streams even across heavy churn. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
matheus23
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FWIW we merge upstream Quinn into noq every now and then. So this would've made it into noq after getting merged into Quinn anyways.
The good news is that by submitting this here now you're probably getting this PR into an earlier release (we're probably releasing again on Monday).
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I think the only failing CI is an action that wants to write a comment on this PR but can't because it was submitted from a fork or sth like that. |
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Port of quinn-rs/quinn#2601.
StreamsState::newused to eagerly insert(id, None)placeholder entries in bothsendandrecvFxHashMaps for every remote stream id in0..max_remote[dir]. Withmax_concurrent_*_streams = 10_000(e.g. for MoQ relay nodes that burn through short-lived streams), hashbrown rounded each map's bucket array up to ~65K buckets, costing ~0.5-2 MB of bucket memory per Connection before any stream data was sent.