As metrics.db grew (1 sample/5 s × hours), handleMetricsChartSVG called
LoadAll() on every chart request — loading all rows across 4 tables through a
single SQLite connection. With ~10 charts auto-refreshing in parallel, requests
queued behind each other, saturating the connection pool and pegging a CPU core.
Fix: add a background compactor that runs every hour via the metrics collector:
• Downsample: rows older than 2 h are thinned to 1 per minute (keep MIN(ts)
per ts/60 bucket) — retains chart shape while cutting row count by ~92 %.
• Prune: rows older than 48 h are deleted entirely.
• After prune: WAL checkpoint/truncate to release disk space.
LoadAll() in handleMetricsChartSVG is unchanged — it now stays fast because
the DB is kept small rather than capping the query window.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Michael Chus
52c3a24b76