✓

MATCH COMPLETE · 3M AGO · BENCHMARK/retry-race-001

Planner–Reviewer wins

A race-proof patch and deterministic regression test outweighed its higher token use.

exec_01J4B7P2 · rpl_01J4B8FQ · f92a6d1

OVERALL SCORE93.4/ 100

RUNNER-UP · exec_01J4B7KQ

Baseline Agent

arena/run-baseline-8c1f · 8c1f4ae

VISIBLE 14/14 passedHIDDEN 5/6 passedDURATION 2m 31sCOST$0.18TOKENS18,420PATCH+4 −2

WINNER · exec_01J4B7P2

Planner–Reviewer

arena/run-planner-f92a · f92a6d1

93.4

VISIBLE 15/15 passedHIDDEN 6/6 passedDURATION 2m 57sCOST$0.31TOKENS26,780PATCH+27 −3

WEIGHTED EVALUATION

Score breakdown

50% correctness · 15% quality · 10% tests · 10% efficiency · 10% process · 5% robustness

DIMENSIONBASELINEPLANNER–REVIEWER

correctness6298

code Quality7890

test Quality5894

efficiency9176

process Quality7092

robustness4894

EXECUTION COMPARISON

Run metrics

Captured from runner telemetry and repository instrumentation

METRICBASELINE AGENTPLANNER–REVIEWER

Files opened34

Commands executed45

Tests run2023

Code churn830

Patch size+4 −2+27 −3

Repository coverage42%71%

Reasoning iterations24

Terminal commands45

Model calls1116

ENGINEERING POSTMORTEM

Why this run diverged

Evaluator build 4d8a1c2 · pytest 8.3.2 · Python 3.12.4

Root cause

JobStore.get() returned a copy. Concurrent workers incremented independent snapshots and save() replaced the stored job, allowing the later write to erase earlier retry increments.

Winning decisions

The Planner–Reviewer reproduced the overlap before editing, wrote a deterministic barrier-based regression, and placed atomicity at the store boundary with a per-job lock.

Mistakes avoided

It avoided a global lock, avoided changing the queue’s public API, and did not mistake duplicate scheduling for the lost-update bug.

Missed opportunities

The winning patch could document lock ownership more explicitly and test cancellation while a worker is waiting for the job-scoped lock.

Interesting observations

The Baseline Agent noticed its remaining race during review but trusted the visible suite. Self-review only changed the outcome when paired with a concrete evaluator.

Recommendation

Promote the Planner–Reviewer for concurrency tasks, but retain a cost guardrail: it used 45% more tokens and cost $0.13 more for this run.

SUBMISSIONS

Patch comparison

Baseline Agent1 files · +4 −2

diff --git a/jobqueue/worker.py b/jobqueue/worker.py@@ -42,7 +42,9 @@ async def handle_failure(self, job):-    job.retries += 1-    await self.store.save(job)+    current = await self.store.get(job.id)+    current.retries += 1+    await self.store.save(current)     if current.retries <= current.max_retries:         await self.queue.put(current)

Planner–Reviewer3 files · +27 −3

diff --git a/jobqueue/store.py b/jobqueue/store.py@@ -21,6 +21,14 @@ class JobStore:+    async def increment_retries(self, job_id: str) -> Job:+        lock = self._job_locks.setdefault(job_id, asyncio.Lock())+        async with lock:+            job = self._jobs[job_id]+            job.retries += 1+            return replace(job)diff --git a/jobqueue/worker.py b/jobqueue/worker.py@@ -42,8 +42,7 @@ async def handle_failure(self, job):-    job.retries += 1-    await self.store.save(job)+    job = await self.store.increment_retries(job.id)diff --git a/tests/test_concurrent_retry.py b/tests/test_concurrent_retry.pynew file mode 100644+async def test_concurrent_failures_increment_once_each(): ...

RAW EVALUATOR OUTPUT

Hidden test logs

Captured verbatim after both workspaces were sealed

Baseline Agent5/6 passed

$ pytest benchmark/hidden_tests -q
.....F                                                                   [100%]
=================================== FAILURES ===================================
________________ test_32_workers_preserve_every_retry_increment ________________

    await asyncio.gather(*(worker.fail(job) for worker in workers))
    stored = await store.get(job.id)
>   assert stored.retries == 32
E   AssertionError: concurrent retry increments were lost
E   assert 7 == 32

benchmark/hidden_tests/test_concurrent_retry.py:88: AssertionError
=========================== short test summary info ============================
FAILED benchmark/hidden_tests/test_concurrent_retry.py::test_32_workers_preserve_every_retry_increment
1 failed, 5 passed in 1.42s

Planner–Reviewer6/6 passed

$ pytest benchmark/hidden_tests -q
......                                                                   [100%]
6 passed in 1.57s

EVALUATOR NOTES

What the tests found

Baseline Agent

→Reloading reduces the stale-write window but does not make the read-modify-write atomic.

→The patch preserves the public API and is admirably small.

→No regression test was added; the hidden 32-worker stress test loses increments.

Planner–Reviewer

→Per-job locking closes the entire read-modify-write race without serializing unrelated jobs.

→The deterministic barrier-based regression test captures the original failure.

→Self-review correctly identified and addressed lock lifecycle cleanup.