# The Multivac — Evaluation Report

**Evaluation ID:** EVAL-20260317-020251
**Date:** Mar 17, 2026
**Category:** code
**Question ID:** EVAL-20260317-020251

---

## Question

This distributed lock implementation has a subtle race condition that can cause two processes to hold the lock simultaneously. Find the bug and fix it.

```python
import redis
import time
import uuid

class DistributedLock:
    def __init__(self, redis_client, lock_name, timeout=10):
        self.redis = redis_client
        self.lock_name = f"lock:{lock_name}"
        self.timeout = timeout
        self.token = str(uuid.uuid4())

    def acquire(self):
        while True:
            if self.redis.setnx(self.lock_name, self.token):
                self.redis.expire(self.lock_name, self.timeout)
                return True
            time.sleep(0.1)

    def release(self):
        if self.redis.get(self.lock_name) == self.token:
            self.redis.delete(self.lock_name)
```

Explain why this is dangerous in production and provide a correct implementation.

---

## Winner

**Qwen 3.5 397B-A17B** (openrouter)
- Winner Score: 9.74
- Matrix Average: 9.14
- Total Judgments: 43

---

## Rankings

| Rank | Model | Provider | Avg Score | Judgments |
|------|-------|----------|-----------|----------|
| 1 | Qwen 3.5 397B-A17B | openrouter | 9.74 | 7 |
| 2 | Qwen 3 8B | openrouter | 9.63 | 5 |
| 3 | Qwen 3.5 122B-A10B | openrouter | 9.49 | 7 |
| 4 | Qwen 3.5 27B | openrouter | 9.34 | 7 |
| 5 | Qwen 3 Coder Next | openrouter | 9.14 | 5 |
| 6 | Qwen 3.5 35B-A3B | openrouter | 8.79 | 7 |
| 7 | Qwen 3.5 9B | openrouter | 7.83 | 5 |

---

## 10×10 Judgment Matrix

Rows = Judge, Columns = Respondent. Self-judgments excluded (—).

| Judge ↓ / Resp → | Qwen 3.5 9B | Qwen 3 8B | Qwen 3 32B | Qwen 3 | Qwen 3.5 | Qwen 3.5 27B | Qwen 3.5 | Qwen 3.5 |
|---|---|---|---|---|---|---|---|---|
| Qwen 3.5 9B | — | 9.8 | · | · | 8.8 | 8.8 | 9.0 | 9.6 |
| Qwen 3 8B | 9.2 | — | · | 9.8 | 10.0 | 10.0 | 10.0 | 10.0 |
| Qwen 3 32B | 8.3 | 10.0 | — | 10.0 | 10.0 | 10.0 | 10.0 | 8.8 |
| Qwen 3 | 9.0 | 10.0 | · | — | 10.0 | 10.0 | 10.0 | 10.0 |
| Qwen 3.5 | 6.3 | · | · | 8.6 | — | 8.2 | 9.0 | 10.0 |
| Qwen 3.5 27B | · | · | · | 8.6 | 7.9 | — | 8.8 | 9.8 |
| Qwen 3.5 | 6.3 | 8.6 | · | 8.8 | 8.2 | 8.6 | — | 10.0 |
| Qwen 3.5 | · | 9.8 | · | · | 6.7 | 9.8 | 9.6 | — |

---

## Methodology

- **10×10 Blind Peer Matrix:** All models answer the same question, then all models judge all responses.
- **5 Criteria:** Correctness, completeness, clarity, depth, usefulness (each scored 1–10).
- **Self-judgments excluded:** Models do not judge their own responses.
- **Weighted Score:** Composite of all 5 criteria.

---

## Citation

The Multivac (2026). Blind Peer Evaluation: EVAL-20260317-020251. app.themultivac.com

## License

Open data. Free to use, share, and build upon. Please cite The Multivac when using this data.

Download raw JSON: https://app.themultivac.com/api/evaluations/EVAL-20260317-020251/results
Full dataset: https://app.themultivac.com/dashboard/export