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fix(jobs): 无 Redis 时用数据库租约保证「一个 tick 只跑一个副本」 - #39
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对标 #12.5 暴露的真缺口：`MemoryJobBackend` 每个副本各有一份 `setInterval`， 两个副本同时到点就是同一批「到期暂停 / 回收站清理 / outbox 转发」各跑两遍。 之前只有一行启动 warn，把「集群安全」写成了运维自觉 —— 而对标对象 （ZJMF `Cron.php` 的 `cron_lock` + 5 分钟陈旧期）同样场景下反而不会重复。 ## 做法 - `kernel_job_leases(name, holder, expiresAtMs)` + 一条语句完成抢占： `INSERT ... ON CONFLICT DO UPDATE ... WHERE expiresAtMs < now RETURNING name`。 命中即执行，空结果集即跳过 —— 并发时由行锁保证只有一个副本能命中。 - 租约按时间自然过期，**不需要死节点检测**：持有者被 kill，最多一个间隔后 就有别的副本接手。 - 租约时长 = 任务间隔（下限 1s / 上限 5 分钟）。取「间隔的若干倍」会把有效频率 压到几倍间隔以下 —— 抢到的副本每轮都成功、其余副本整个窗口全部跳过。 - 抢租约出错按「没抢到」处理：宁可这一轮不跑（下轮补），也不因数据库抖一下 变成多副本重复执行。 - 只给进程内后端用。BullMQ 本身按队列抢占，再套一层会让重试互相挡住。 ## 验证 - `tests/unit/job-lease-memory.test.ts` 4 例：抢到才执行 / 没抢到静默跳过 / 租约抛错时跳过且告警 / 租约时长取一个间隔（含 1s 下限、5min 上限）。 - `tests/integration/job-lease.test.ts` 4 例真实 DB：两副本只有一个抢到 / 过期后接手 / 不同任务互不阻塞 / 同一副本租约内不能自我放行。 - 既有 `tests/unit/jobs.test.ts`、`tests/unit/jobs-contract.test.ts` 全绿（21 例合计）。 - `tsc` 干净。 顺带一句：写测试时踩到「四个用例共用同一个任务名」——第二例被第一例的未过期租约 挡住，看起来像实现错了。用例已按任务名隔离，并在注释里写明原因。
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对标 #12.5 暴露的真缺口：
MemoryJobBackend每个副本各有一份setInterval，两个副本同时到点就是同一批「到期暂停 / 回收站清理 / outbox 转发」各跑两遍。之前只有一行启动 warn，把「集群安全」写成了运维自觉 —— 而对标对象（ZJMFCron.php的cron_lock+ 5 分钟陈旧期）在同样场景下反而不会重复。做法
kernel_job_leases(name, holder, expiresAtMs)+ 一条语句完成抢占：INSERT ... ON CONFLICT DO UPDATE ... WHERE expiresAtMs < now RETURNING name。命中即执行，空结果集即跳过 —— 并发时由行锁保证只有一个副本能命中验证
tests/unit/job-lease-memory.test.ts4 例：抢到才执行 / 没抢到静默跳过 / 租约抛错时跳过且告警 / 租约时长取一个间隔（含 1s 下限、5min 上限）tests/integration/job-lease.test.ts4 例真实 DB：两副本只有一个抢到 / 过期后接手 / 不同任务互不阻塞 / 同一副本租约内不能自我放行jobs.test.ts、jobs-contract.test.ts全绿（合计 21 例）；tsc干净边界
租约只抑制「同一轮多副本并发执行」；间隔短于处理器执行时长时仍可能重叠（与握手前的行为相同，未变差）。真要做到严格串行需要按任务加长租约或改用 BullMQ。