# The Multivac — Evaluation Report

**Evaluation ID:** EVAL-20260317-022129
**Date:** Mar 17, 2026
**Category:** code
**Question ID:** EVAL-20260317-022129

---

## Question

Your Node.js API is responding with 502 errors under load. Here's the relevant code and infrastructure:

- Express.js API behind an Nginx reverse proxy
- Connection pool to PostgreSQL (max 20 connections)
- Average response time: 50ms normally, 30s+ during incidents
- Error logs show: "connect ETIMEDOUT" and "too many clients already"
- The issue starts when traffic exceeds 200 req/s

```javascript
app.get('/api/users/:id', async (req, res) => {
  const client = await pool.connect();
  const result = await client.query('SELECT * FROM users WHERE id = $1', [req.params.id]);
  res.json(result.rows[0]);
});
```

What's wrong? Provide the fix and explain the connection pool exhaustion pattern.

---

## Winner

**Qwen 3.5 35B-A3B** (openrouter)
- Winner Score: 9.89
- Matrix Average: 9.47
- Total Judgments: 50

---

## Rankings

| Rank | Model | Provider | Avg Score | Judgments |
|------|-------|----------|-----------|----------|
| 1 | Qwen 3.5 35B-A3B | openrouter | 9.89 | 7 |
| 2 | Qwen 3.5 122B-A10B | openrouter | 9.77 | 7 |
| 3 | Qwen 3 32B | openrouter | 9.70 | 4 |
| 4 | Qwen 3 Coder Next | openrouter | 9.58 | 7 |
| 5 | Qwen 3.5 27B | openrouter | 9.52 | 6 |
| 6 | Qwen 3.5 9B | openrouter | 9.34 | 6 |
| 7 | Qwen 3.5 397B-A17B | openrouter | 9.11 | 7 |
| 8 | Qwen 3 8B | openrouter | 8.82 | 6 |

---

## 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 | — | 8.6 | · | 8.8 | 9.8 | 8.6 | 9.2 | 5.0 |
| Qwen 3 8B | 9.8 | — | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 |
| Qwen 3 32B | 9.4 | 9.6 | — | 9.6 | 10.0 | 10.0 | 9.6 | 9.6 |
| Qwen 3 | 10.0 | 10.0 | 10.0 | — | 10.0 | 10.0 | 10.0 | 10.0 |
| Qwen 3.5 | · | · | 10.0 | 9.8 | — | · | 10.0 | 10.0 |
| Qwen 3.5 27B | 9.3 | 7.3 | · | 9.3 | 9.6 | — | 9.6 | 9.6 |
| Qwen 3.5 | 8.2 | 8.0 | 8.8 | 9.6 | 9.8 | 9.0 | — | 9.6 |
| Qwen 3.5 | 9.3 | 9.3 | · | 10.0 | 10.0 | 9.6 | 10.0 | — |

---

## 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-20260317-022129. 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-20260317-022129/results
Full dataset: https://app.themultivac.com/dashboard/export