Reworks the post-fetch half of the propagation pipeline. Fetch and GRIB2
decode were already cheap — measured against a live HRRR cycle, all 39
pressure messages decode via `wgrib2 -lola` in 0.29 s and the 31 MB
byte-range fetch takes ~3 s — so nothing here touches the decoder. All the
cost was downstream.
Also fixes a broken NOTIFY that made every chain step run up to 5 times.
pg_notify
`NOTIFY propagation_ready, $1` is a Postgres syntax error: NOTIFY is a
utility statement whose payload must be a literal, so a bind raises
42601. It shared a transaction with the `status='done'` UPDATE, so every
successful step rolled back, stayed 'running', and was requeued by
reclaim_stale_running up to @max_reclaim_attempts times. Elixir's
NotifyListener never fired either, so ScoreCache warm and the
"propagation:updated" fan-out were dead.
FieldGrid
A decoded grid was HashMap<(i32,i32), HashMap<Arc<str>, f32>> — a dense
rectangular grid stored as ~95k nested hash maps, costing ~4.6M inserts
on decode, ~3.7M on merge and ~14M lookups across three derivation
passes. wgrib2 -lola already emits one dense row-major f32 block per
message, so keep it: dense per-message planes, names hashed once per
grid into plane ids, NaN as the missing sentinel. This is what forced
PROP_GRID_RS_PARALLELISM=1 under a 3Gi limit.
Fused pass
Three 95k-cell derivation passes plus 23 band-major scoring passes over
a staged Vec<(f64,f64,Conditions,BandInvariants)> (~19MB re-streamed 23
times) collapse into one pass: levels extracted once per cell, all 23
bands scored while the cell is hot, scores accumulated cell-major so
rayon chunks own disjoint slices. Scores land straight in the dense
score-file body — no ScorePoint scatter.
.pgrid
The profile artifact was an rmpv tree plus gzip -9, written 30x an hour,
and ProfilesFile.read_point/3 gunzipped and unpacked the entire 95k-cell
file to return one cell on every map click and Skew-T load. Replaced
with a dense cell-major f32 record array carrying a self-describing
field table. Elixir reads it via :file.pread; .mp.gz and .etf.gz remain
readable so files written before this drain out of the 48h window.
Measured on a full CONUS grid (95,073 cells x 48 planes x 23 bands):
derive + score + build artifacts 0.022 s
profile write 3.957 s -> 0.006 s (22.0 MB -> 22.4 MB on disk)
single-cell read whole-file decode -> 0.5 us
23 score files 0.003 s
Also
- hrrr_points: batched UNNEST upsert replacing one awaited INSERT per
point. Keeps ON CONFLICT DO UPDATE — the PSKR sampler's two-pass loop
depends on it.
- fetcher: real semaphore capping in-flight ranges at
MAX_PARALLEL_RANGES, which the comment claimed but the code did not do
(it spawned all 27 while the connection pool was sized for 8).
- metrics: per-stage histogram. Only chain-step and decode durations
were instrumented, which is why the write cost stayed invisible.
- profiles_file: parse_valid_time anchors on the known extension set, so
sibling-suffixed names like <iso>.hrdps.prop no longer parse as
<iso>.hrdps and vanish from prune and list operations.
- PROP_GRID_RS_PARALLELISM 1 -> 3. Memory limit held at 3Gi until RSS is
observed at the new parallelism.
- cargo fmt over the crate; worker.rs, hrdps_fetcher.rs and nexrad.rs
were already unformatted at HEAD and the pre-commit hook gates on it.
HRDPS still runs at 0.5 degrees. wgrib2 -lola scales linearly in output
points on rotated lat/lon (12.5 s wall, 202 s CPU for one message at
0.125 degrees) because it has no inverse projection for those grids; a raw
native dump is 0.32 s. The fix is decode-once plus a closed-form
rotated-pole index, left for a follow-up.
Graham McIntire
63f25a9612