Four changes sized by measured prod telemetry (83m of spans):
1. propagation queue: 2 → 1 slot per pod. Two concurrent forecast-hour
steps per pod stacked HRRR grid + native duct grid + scored band
map into ~5-6 GiB RSS, OOM-killing every ~15 min. 3-way parallelism
cluster-wide still finishes the chain inside the hourly interval.
2. weather queue: 3 → 1 slot per pod. ASOS backfill was 429-thrashing
IEM (1,296 retryable jobs; logs were nothing but 429 backoffs).
3. PropagationGridWorker: skip native-level duct fetch on f01..f18.
At ~7-11 min/fh and 18 forecast hours, this was the largest single
cost per chain. Forecast hours fall back to
derived[:min_refractivity_gradient] from the pressure-level
profile. f00 still gets full native-level duct analysis.
4. HrrrClient.download_grib_ranges_to_file: parallelize with
Task.async_stream (max_concurrency 8). The file-backed variant was
sequential, dominating native-duct fetch time on the remaining f00
path. ~20s → ~3s per call.
Graham McIntire
01b181b1e8