{
  "evaluation_id": "EVAL-20260317-022129",
  "question_id": "EVAL-20260317-022129",
  "question_text": "Your Node.js API is responding with 502 errors under load. Here's the relevant code and infrastructure:\n\n- Express.js API behind an Nginx reverse proxy\n- Connection pool to PostgreSQL (max 20 connections)\n- Average response time: 50ms normally, 30s+ during incidents\n- Error logs show: \"connect ETIMEDOUT\" and \"too many clients already\"\n- The issue starts when traffic exceeds 200 req/s\n\n```javascript\napp.get('/api/users/:id', async (req, res) => {\n  const client = await pool.connect();\n  const result = await client.query('SELECT * FROM users WHERE id = $1', [req.params.id]);\n  res.json(result.rows[0]);\n});\n```\n\nWhat's wrong? Provide the fix and explain the connection pool exhaustion pattern.",
  "category": "code",
  "timestamp": "2026-03-17T02:21:29.507Z",
  "display_date": "Mar 17, 2026",
  "winner": {
    "name": "Qwen 3.5 35B-A3B",
    "provider": "openrouter",
    "score": 9.89
  },
  "avg_score": 9.46625,
  "matrix_size": 50,
  "models_used": [
    {
      "id": "qwen3_8b",
      "name": "Qwen 3 8B",
      "provider": "openrouter"
    },
    {
      "id": "qwen3_coder_next",
      "name": "Qwen 3 Coder Next",
      "provider": "openrouter"
    },
    {
      "id": "qwen35_35b_a3b",
      "name": "Qwen 3.5 35B-A3B",
      "provider": "openrouter"
    },
    {
      "id": "qwen35_27b",
      "name": "Qwen 3.5 27B",
      "provider": "openrouter"
    },
    {
      "id": "qwen35_122b_a10b",
      "name": "Qwen 3.5 122B-A10B",
      "provider": "openrouter"
    },
    {
      "id": "qwen35_397b_a17b",
      "name": "Qwen 3.5 397B-A17B",
      "provider": "openrouter"
    },
    {
      "id": "qwen35_9b",
      "name": "Qwen 3.5 9B",
      "provider": "openrouter"
    },
    {
      "id": "qwen3_32b",
      "name": "Qwen 3 32B",
      "provider": "openrouter"
    }
  ],
  "rankings": {
    "qwen35_35b_a3b": {
      "display_name": "Qwen 3.5 35B-A3B",
      "provider": "openrouter",
      "average_score": 9.89,
      "score_count": 7,
      "min_score": 9.6,
      "max_score": 10,
      "rank": 1
    },
    "qwen35_122b_a10b": {
      "display_name": "Qwen 3.5 122B-A10B",
      "provider": "openrouter",
      "average_score": 9.77,
      "score_count": 7,
      "min_score": 9.2,
      "max_score": 10,
      "rank": 2
    },
    "qwen3_32b": {
      "display_name": "Qwen 3 32B",
      "provider": "openrouter",
      "average_score": 9.7,
      "score_count": 4,
      "min_score": 8.8,
      "max_score": 10,
      "rank": 3
    },
    "qwen3_coder_next": {
      "display_name": "Qwen 3 Coder Next",
      "provider": "openrouter",
      "average_score": 9.58,
      "score_count": 7,
      "min_score": 8.8,
      "max_score": 10,
      "rank": 4
    },
    "qwen35_27b": {
      "display_name": "Qwen 3.5 27B",
      "provider": "openrouter",
      "average_score": 9.52,
      "score_count": 6,
      "min_score": 8.55,
      "max_score": 10,
      "rank": 5
    },
    "qwen35_9b": {
      "display_name": "Qwen 3.5 9B",
      "provider": "openrouter",
      "average_score": 9.34,
      "score_count": 6,
      "min_score": 8.15,
      "max_score": 10,
      "rank": 6
    },
    "qwen35_397b_a17b": {
      "display_name": "Qwen 3.5 397B-A17B",
      "provider": "openrouter",
      "average_score": 9.11,
      "score_count": 7,
      "min_score": 5,
      "max_score": 10,
      "rank": 7
    },
    "qwen3_8b": {
      "display_name": "Qwen 3 8B",
      "provider": "openrouter",
      "average_score": 8.82,
      "score_count": 6,
      "min_score": 7.35,
      "max_score": 10,
      "rank": 8
    }
  },
  "judgments": [
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 8.6,
      "brief_justification": "The response accurately identifies the connection leak issue and provides correct fixes with clear implementation. It covers root cause, impact, and solutions comprehensively. Could include monitoring recommendations for production scenarios."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 8.8,
      "brief_justification": "Response accurately diagnoses connection pool exhaustion, provides correct try/finally fix, and offers comprehensive additional recommendations including pool.query() usage, timeouts, and monitoring. Minor opportunity to mention Nginx upstream timeout configuration as complementary fix."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 9.8,
      "brief_justification": "Response accurately identifies the connection leak issue, provides multiple valid fixes with proper code examples, and includes comprehensive infrastructure recommendations. The explanation is technically sound with clear structure and actionable guidance."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 8.55,
      "brief_justification": "Excellent diagnosis and fix with clear code examples. Minor technical inaccuracy: 'too many clients already' in pg driver context indicates pool exhaustion, not necessarily PostgreSQL server max_connections limit. Otherwise comprehensive coverage of the issue."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 9.2,
      "brief_justification": "Excellent diagnosis identifying the missing connection release as the root cause. Response provides accurate fixes, proper timeout configurations, and clear explanations of the exhaustion pattern. Minor deduction for not mentioning that pool.query() requires pg version 8+."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 5,
      "brief_justification": "Critical factual error: The code shown does NOT leak connections - async functions automatically release pool connections when they complete. The real issues are likely pool size being too small for 200 req/s, slow queries causing timeouts, or connection leaks in other code paths not shown. This incorrect diagnosis makes the fix ineffective for the actual problem."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9.8,
      "brief_justification": "The response accurately identifies connection leaks and pool sizing as root causes, provides correct code fixes, and offers comprehensive infrastructure recommendations. It thoroughly explains the connection exhaustion pattern and includes actionable solutions."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen3_32b",
      "respondent_name": "Qwen 3 32B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies connection pool exhaustion as the root cause, provides actionable fixes, explains the error pattern in detail, and offers comprehensive optimization strategies. All criteria are fully addressed with precise technical explanations and practical solutions."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 10,
      "brief_justification": "The response thoroughly explains connection pool exhaustion, provides actionable fixes, and includes detailed recommendations. It covers the root cause, code examples, and preventive measures with clear structure and depth."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 10,
      "brief_justification": "The response thoroughly explains connection pool exhaustion, provides actionable fixes, and includes infrastructure recommendations. It covers all aspects of the problem with clear examples and impact analysis."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the connection leak as the root cause, provides actionable fixes, explains the cascading failure pattern, and includes infrastructure recommendations. It thoroughly covers all aspects of the problem with clear, structured explanations."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies connection pool exhaustion as the root cause, provides actionable fixes with code examples, and thoroughly explains the failure pattern including Nginx/PostgreSQL interactions. All criteria are met with exceptional depth and practical value."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies connection pool exhaustion as the root cause, provides correct fixes with code examples, and thoroughly explains the pattern with timelines and metrics. All recommendations are actionable and directly address the problem."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9.4,
      "brief_justification": "Accurately identifies connection leaks and pool size limitations as root causes, provides precise code fixes with `client.release()` in `finally`, and includes infrastructure optimizations. Explains the exhaustion pattern thoroughly but could better quantify pool sizing logic."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 9.6,
      "brief_justification": "The response accurately identifies the missing `client.release()` as the root cause of connection leaks and provides a clear, actionable fix. It thoroughly explains the connection pool exhaustion pattern, impact on PostgreSQL, and includes code examples for both application and database configuration. The only minor omission is not mentioning potential Nginx timeout tuning, but the core issue is addressed comprehensively."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 9.6,
      "brief_justification": "Accurately identifies connection leakage as the root cause, provides precise code fixes with `try/finally`, and offers comprehensive additional recommendations (pool.query, timeouts, monitoring). Explains the exhaustion pattern with a clear phase table and actionable solutions."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the connection leak as the root cause, provides multiple code fixes, and offers comprehensive infrastructure recommendations. It explains the problem clearly with code examples and impact analysis, while also addressing both immediate fixes and long-term scalability solutions."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the connection leak as the root cause, provides precise code fixes, and thoroughly explains the exhaustion pattern with infrastructure recommendations. It balances technical depth with actionable solutions."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 9.6,
      "brief_justification": "Accurately identifies connection leaks, timeout misconfigurations, and pool sizing issues. Provides code fixes using pool.query(), timeout settings, and Nginx adjustments. Explains the exhaustion pattern with a clear analogy and includes a practical checklist for monitoring and scaling."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 9.6,
      "brief_justification": "Accurately identifies connection leak as root cause, provides multiple fixes with code examples, explains pool exhaustion pattern, and includes monitoring/tuning recommendations. Clear structure and actionable solutions make it highly practical."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the root cause (connection leak + insufficient pool size), provides correct, production-ready code fixes with proper `try/finally` usage, recommends actionable infrastructure optimizations (Nginx, monitoring), and explains the connection exhaustion pattern thoroughly and clearly."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the root cause (missing client.release()), explains the connection pool exhaustion mechanism in detail, provides a correct and robust fix with try/finally, and includes actionable secondary optimizations (pool config, DB tuning). It is thorough, technically precise, and highly practical."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen3_32b",
      "respondent_name": "Qwen 3 32B",
      "weighted_score": 10,
      "brief_justification": "The response correctly identifies the root cause (missing `client.release()`), provides two robust fixes with code examples, thoroughly explains the connection pool exhaustion pattern step-by-step, and includes valuable additional optimizations—making it factually accurate, comprehensive, clear, insightful, and highly actionable."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the root cause (connection leak), provides multiple correct and practical fixes, explains the exhaustion pattern thoroughly, and adds valuable infrastructure recommendations with concrete examples and impact analysis—demonstrating deep technical insight and actionable guidance."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 10,
      "brief_justification": "The response correctly identifies the connection leak, explains the pool exhaustion cascade in detail, provides two robust fixes with code examples, and includes infrastructure recommendations—demonstrating deep technical insight and actionable guidance."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 10,
      "brief_justification": "The response correctly identifies the root cause (missing connection release), explains the exhaustion pattern with vivid analogies, provides actionable fixes including code changes, pool tuning, and Nginx configuration, and includes critical infrastructure considerations like multi-instance scaling and PostgreSQL limits—all with precise technical detail and clear structure."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 10,
      "brief_justification": "The response correctly identifies connection pool exhaustion due to missing `client.release()`, provides two robust fixes with clear trade-offs, includes actionable monitoring and tuning recommendations, and supports analysis with expected metrics—demonstrating deep understanding of both the symptom and root cause."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen3_32b",
      "respondent_name": "Qwen 3 32B",
      "weighted_score": 10,
      "brief_justification": "The model accurately identified the missing client.release() as the root cause of the connection leak, provided correct code fixes, and clearly explained the interaction between the Node.js pool, PostgreSQL limits, and Nginx timeouts."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 9.75,
      "brief_justification": "The response accurately diagnoses the connection leak and provides the correct `try/finally` fix, though the monitoring snippet uses non-standard `pg` library properties. It offers comprehensive, actionable advice including `pool.query()` usage and timeout configurations."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 10,
      "brief_justification": "The response accurately diagnoses the critical connection leak and provides a holistic solution covering code, infrastructure, and configuration. It offers deep insight into the interaction between Node, Postgres, and Nginx while remaining highly actionable."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 10,
      "brief_justification": "The response correctly identifies the critical connection leak, provides idiomatic fixes, clearly explains the exhaustion pattern, and offers valuable monitoring and tuning recommendations."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9.35,
      "brief_justification": "The response accurately diagnoses the connection leak and provides a correct fix using try/finally, along with valuable infrastructure recommendations. It loses minor points for not suggesting pool.query() as a simpler alternative for single queries."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 7.35,
      "brief_justification": "The response correctly identifies the connection leak (missing client.release()) and provides working fixes, but misses mentioning the simpler pool.query() pattern and makes some debatable claims about pool capacity requirements."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 9.35,
      "brief_justification": "The response correctly identifies the missing client.release() as the root cause and provides accurate fixes with try/finally and pool.query() alternatives. Minor inaccuracy with pool.using property name, but overall excellent technical accuracy with comprehensive coverage of the issue, prevention strategies, and monitoring recommendations."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 9.6,
      "brief_justification": "The response correctly identifies the connection leak bug and provides accurate, actionable fixes with multiple implementation options. Infrastructure recommendations and monitoring suggestions add significant practical value, though could have explored connection pool internals slightly deeper."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 9.6,
      "brief_justification": "The response accurately identifies the critical connection leak bug (missing client.release()), provides correct fixes with proper timeout configuration, and thoroughly explains the pool exhaustion pattern with practical Nginx and monitoring recommendations."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 9.55,
      "brief_justification": "The response accurately diagnoses the connection leak and provides the correct primary fix using pool.query() or proper release(). Minor deductions for the 'Additional Recommendations' section containing non-standard API calls (e.g., res.setTimeout, pool.totalCount) that may not run as written, though the core solution is flawless."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 8.15,
      "brief_justification": "Correctly identifies the connection leak as the primary issue and provides accurate code fixes. Pool size recommendations are reasonable but could benefit from more mathematical justification for the 200 req/s scenario. Well-structured with actionable infrastructure recommendations."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 8,
      "brief_justification": "Correctly identifies the missing client.release() as the root cause with proper fix using try/finally. Configuration recommendations could be more nuanced (pool max of 100 may exceed DB limits with multiple app instances), and Nginx 502 specifics could be explored further."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen3_32b",
      "respondent_name": "Qwen 3 32B",
      "weighted_score": 8.8,
      "brief_justification": "The response correctly identifies the missing client.release() as the root cause and provides accurate fixes. The connection pool exhaustion pattern is well explained, though there's minor conflation between pool exhaustion and PostgreSQL max_connections limits. Overall highly actionable with clear code examples."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 9.55,
      "brief_justification": "Response correctly identifies connection leakage as the root cause with accurate fix using try/finally. Minor issue: 'user not found' wouldn't throw an error. Comprehensive coverage with multiple solutions, monitoring recommendations, and clear pattern explanation."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 9.8,
      "brief_justification": "The response accurately identifies the missing connection release as the root cause and provides comprehensive code fixes and infrastructure recommendations. It clearly explains the exhaustion pattern and offers actionable solutions for immediate and long-term stability."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 9,
      "brief_justification": "The response correctly identifies the connection leak as the root cause and provides accurate fixes with working code examples. It thoroughly explains the pool exhaustion pattern, the 502 error cascade, and includes practical infrastructure recommendations. Minor deduction for slightly imprecise explanation of the 'too many clients' error origin."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 9.6,
      "brief_justification": "Accurately diagnoses the connection leak with correct fixes and comprehensive recommendations. Well-structured with actionable code examples, though Nginx timeout configuration could be more explicit."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9.35,
      "brief_justification": "Accurately identifies the connection leak and provides actionable fixes, though slightly misstates pool mechanics and omits the simpler `pool.query()` alternative."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 9.35,
      "brief_justification": "Accurately identifies the critical connection leak and provides a safe fix, though the claim about pool size insufficiency overlooks theoretical throughput capacity. Explanation is clear and actionable, but could mention pool.query() as a simpler alternative."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the missing client.release() as the root cause and provides correct code fixes using try/finally and pool.query(). It thoroughly explains the exhaustion pattern with a clear table and offers valuable operational recommendations like monitoring and timeouts."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 10,
      "brief_justification": "The response accurately diagnoses the connection leak, provides multiple valid code fixes, and offers comprehensive infrastructure recommendations. It is well-structured, technically precise, and immediately actionable."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 9.55,
      "brief_justification": "Accurately diagnoses the connection leak and offers the best practice fix, though Option 2 contains a minor Express syntax error. The explanation of the exhaustion pattern and infrastructure advice is thorough and actionable."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the missing connection release as the root cause and provides best-practice code fixes using pool.query(). It thoroughly explains the infrastructure interactions causing 502 errors and offers actionable configuration changes."
    }
  ],
  "meta": {
    "source": "The Multivac (app.themultivac.com)",
    "methodology": "10x10 blind peer matrix evaluation",
    "criteria": "correctness, completeness, clarity, depth, usefulness",
    "self_judgments": "excluded from rankings",
    "license": "Open data — cite as: The Multivac (2026)"
  }
}