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fix(cascade): 限制批次内并发执行的 handler 数量 - #492
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gloryfromca merged 2 commits intoOct 15, 2026
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This was referenced Oct 14, 2026
gloryfromca
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Oct 15, 2026
The semaphore was built inside drain_once, so two concurrent drains each
got their own and the bound doubled. That overlap is the shipped path:
POST /cascade/quiesce calls drain_fully() before stop() while the
background loop is still draining, which CascadeOrchestrator.drain_fully
documents ("the background worker claims batches too"). A regression
test reproduces it -- peak 8 against a documented bound of 4.
Also pass handler_concurrency through from CascadeConfig. Nothing did,
so the default was hardcoded in production and the positive-value guard
was unreachable; every other worker knob already has a config field.
The existing assertion used <=, which a bound accidentally set to 1
would also satisfy; peak is deterministic here, so pin it with ==.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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问题
cascade worker 在单个批次内对 50 行并发执行 handler。daily-log handler 先按
md_path解析既有行，碎片化的 Lance 表上该查询是原生全量扫描：50 个并发 handler 曾把生产数据回放推到 8.29 GiB 且 80 秒内未完成；1/2/4/8 并发的峰值约 0.26/0.61/0.98/1.73 GiB。原生查询不受 Python 取消控制，超时后仍会成倍占用内存与文件句柄。改法
handler_concurrency（默认 4）：领取批次仍为 50 行保持队列语义，仅限制同时执行的 handler 数量。验证
范围
仅含通用修复与测试。