# The Multivac — Evaluation Report

**Evaluation ID:** EVAL-20260402-130102
**Date:** Apr 02, 2026
**Category:** code
**Question ID:** CODE-011

---

## 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

**Claude Sonnet 4.6** (openrouter)
- Winner Score: 9.44
- Matrix Average: 8.59
- Total Judgments: 84

---

## Rankings

| Rank | Model | Provider | Avg Score | Judgments |
|------|-------|----------|-----------|----------|
| 1 | Claude Sonnet 4.6 | openrouter | 9.44 | 9 |
| 2 | GPT-5.4 | openrouter | 9.41 | 8 |
| 3 | Claude Opus 4.6 | openrouter | 9.27 | 9 |
| 4 | Grok 4.20 | openrouter | 9.18 | 7 |
| 5 | Gemini 3 Flash Preview | Google | 9.08 | 8 |
| 6 | MiMo-V2-Flash | Xiaomi | 9.02 | 9 |
| 7 | GPT-OSS-120B | OpenAI | 8.83 | 9 |
| 8 | MiniMax M2.5 | openrouter | 8.68 | 8 |
| 9 | DeepSeek V4 | openrouter | 7.94 | 8 |
| 10 | Gemini 3.1 Pro | openrouter | 5.06 | 9 |

---

## 10×10 Judgment Matrix

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

| Judge ↓ / Resp → | GPT-5.4 | Claude Opus | Gemini 3.1 Pro | Claude Sonnet | Grok 4.20 | DeepSeek V4 | GPT-OSS-120B | Gemini 3 | MiniMax M2.5 | MiMo-V2-Flash |
|---|---|---|---|---|---|---|---|---|---|---|
| GPT-5.4 | — | 8.4 | 1.6 | 8.8 | 9.0 | 6.0 | 7.5 | 8.6 | 6.8 | 8.6 |
| Claude Opus | 10.0 | — | 2.5 | 9.6 | 9.3 | 9.0 | 9.2 | 9.6 | 8.8 | 9.2 |
| Gemini 3.1 Pro | 8.1 | 8.8 | — | 10.0 | 9.3 | 5.9 | 8.1 | 10.0 | 7.8 | 9.3 |
| Claude Sonnet | 9.8 | 9.8 | 4.3 | — | 8.8 | 8.2 | 9.0 | 8.8 | 9.0 | 8.8 |
| Grok 4.20 | 9.0 | 9.0 | 5.7 | 9.0 | — | 8.8 | 8.7 | 8.6 | 8.8 | 8.6 |
| DeepSeek V4 | 9.6 | 9.8 | 8.6 | 9.6 | 9.8 | — | 10.0 | 9.6 | 9.6 | 9.6 |
| GPT-OSS-120B | 8.8 | 8.8 | 3.4 | 8.8 | · | 8.0 | — | 8.6 | · | 8.6 |
| Gemini 3 | 10.0 | 10.0 | 8.1 | 10.0 | · | 9.8 | 9.6 | — | 10.0 | 10.0 |
| MiniMax M2.5 | 10.0 | 9.4 | 2.5 | 9.8 | 8.8 | 7.8 | 8.6 | 8.8 | — | 8.4 |
| MiMo-V2-Flash | · | 9.3 | 8.8 | 9.3 | 9.2 | · | 8.8 | · | 8.6 | — |

---

## 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: CODE-011. 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-20260402-130102/results
Full dataset: https://app.themultivac.com/dashboard/export