The §7a.6 anomaly probed to its mechanism with five discriminating runs
(§7a.7 table): main-thread B-tree writes triple under attached readers
because READERS PIN WAL checkpoint progress — the deep WAL taxes every
writer page operation (deletes 42.6s pool-off vs 118.8s pool-4 on
identical hardware; an aggressive 64MB valve recovers the writes but
overpays +129s in full-park folds; the v2 cache resurrection was
falsified — long-tail name traffic is uncacheable at any capacity).
Fix: workers close and reopen their read-only connections every 8
batches at the double-buffer's worker-idle boundary
(ResolverPool.recycleWorkers + QueryBuilder.rebind + a cadence call).
Reopens are sub-millisecond, resolver caches survive (only prepared
statements re-prepare), and the existing checkpoints advance instead of
parking. Failed recycle downgrades to sequential, same as a failed
fan-out.
Measured (8c pool-4, linux v7.2-rc2, cadence 25 → 8 iterated):
resolution superphase 715.0 → 633.6s (−11.4%), envelope best 14.8min,
recreate 59.7 → 45.3s. Byte-neutral everywhere: git dumps byte-identical
old-vs-new, linux dump sha 6dd1185b reproduced (10,446,478 lines),
counts 2,049,153/6,413,518, suite 2517 green. 2c unchanged by
construction (no pool → no recycling).
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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