After the cluster's silent-failure incident (75 min between 'alpha
pipeline inputs' and exit, no intervening log line), instrument the
parallel path so any future hang or panic localises to the specific
chunk that died. Each chunk emits start + done lines with chunk_idx,
emit range, warmup_start, row count, and elapsed seconds; the wrapper
also logs dispatch (chunk count + threads + chunk_size) and overall
completion.
Local 1Q smoke (16-thread box):
- dispatching 16 chunks (chunk_size=35485, warmup_bars=2000)
- chunk 0 (cold-start, no warmup shortcut): 19.2s
- chunks 1-15: 13.9-16.5s
- all-chunks-complete log fires before fxcache write
Cost: ~17 info lines per precompute run — negligible. Worth the
observability when the pipeline takes minutes and any future kill
needs root-cause.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
711b6d434d