{
  "evaluation_id": "EVAL-20260317-020251",
  "question_id": "EVAL-20260317-020251",
  "question_text": "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.\n\n```python\nimport redis\nimport time\nimport uuid\n\nclass DistributedLock:\n    def __init__(self, redis_client, lock_name, timeout=10):\n        self.redis = redis_client\n        self.lock_name = f\"lock:{lock_name}\"\n        self.timeout = timeout\n        self.token = str(uuid.uuid4())\n\n    def acquire(self):\n        while True:\n            if self.redis.setnx(self.lock_name, self.token):\n                self.redis.expire(self.lock_name, self.timeout)\n                return True\n            time.sleep(0.1)\n\n    def release(self):\n        if self.redis.get(self.lock_name) == self.token:\n            self.redis.delete(self.lock_name)\n```\n\nExplain why this is dangerous in production and provide a correct implementation.",
  "category": "code",
  "timestamp": "2026-03-17T02:02:51.032Z",
  "display_date": "Mar 17, 2026",
  "winner": {
    "name": "Qwen 3.5 397B-A17B",
    "provider": "openrouter",
    "score": 9.74
  },
  "avg_score": 9.137143,
  "matrix_size": 43,
  "models_used": [
    {
      "id": "qwen3_8b",
      "name": "Qwen 3 8B",
      "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_coder_next",
      "name": "Qwen 3 Coder Next",
      "provider": "openrouter"
    }
  ],
  "rankings": {
    "qwen35_397b_a17b": {
      "display_name": "Qwen 3.5 397B-A17B",
      "provider": "openrouter",
      "average_score": 9.74,
      "score_count": 7,
      "min_score": 8.8,
      "max_score": 10,
      "rank": 1
    },
    "qwen3_8b": {
      "display_name": "Qwen 3 8B",
      "provider": "openrouter",
      "average_score": 9.63,
      "score_count": 5,
      "min_score": 8.55,
      "max_score": 10,
      "rank": 2
    },
    "qwen35_122b_a10b": {
      "display_name": "Qwen 3.5 122B-A10B",
      "provider": "openrouter",
      "average_score": 9.49,
      "score_count": 7,
      "min_score": 8.8,
      "max_score": 10,
      "rank": 3
    },
    "qwen35_27b": {
      "display_name": "Qwen 3.5 27B",
      "provider": "openrouter",
      "average_score": 9.34,
      "score_count": 7,
      "min_score": 8.15,
      "max_score": 10,
      "rank": 4
    },
    "qwen3_coder_next": {
      "display_name": "Qwen 3 Coder Next",
      "provider": "openrouter",
      "average_score": 9.14,
      "score_count": 5,
      "min_score": 8.55,
      "max_score": 10,
      "rank": 5
    },
    "qwen35_35b_a3b": {
      "display_name": "Qwen 3.5 35B-A3B",
      "provider": "openrouter",
      "average_score": 8.79,
      "score_count": 7,
      "min_score": 6.65,
      "max_score": 10,
      "rank": 6
    },
    "qwen35_9b": {
      "display_name": "Qwen 3.5 9B",
      "provider": "openrouter",
      "average_score": 7.83,
      "score_count": 5,
      "min_score": 6.25,
      "max_score": 9.2,
      "rank": 7
    }
  },
  "judgments": [
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 9.8,
      "brief_justification": "The response accurately identifies the race condition between setnx and expire, provides a correct atomic solution using SET with NX/PX and Lua script for release, and thoroughly explains the production risks with clear, well-structured formatting."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 8.8,
      "brief_justification": "Response correctly identifies the setnx/expire race condition and provides a robust Lua-scripted solution. Minor deduction for not explicitly mentioning the release() race condition (get+delete not atomic) in the bug analysis, though it's properly addressed in the fix."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 8.8,
      "brief_justification": "Response correctly identifies both race conditions (non-atomic set/expire and check-then-act in release), provides accurate Lua script fixes, and includes practical production recommendations. Minor deduction for not discussing lock renewal/heartbeat mechanisms for long-running operations."
    },
    {
      "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,
      "brief_justification": "Response accurately identifies the race condition between setnx() and expire() operations, provides correct atomic fixes using Redis SET with NX/EX flags and Lua script for release, and includes comprehensive production considerations."
    },
    {
      "judge_key": "qwen35_9b",
      "judge_name": "Qwen 3.5 9B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 9.6,
      "brief_justification": "The response accurately identifies both race conditions (non-atomic acquire and release), provides correct fixes using Redis atomic operations, and includes production-ready best practices. Minor point deducted for not mentioning lock extension/renewal patterns."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9.2,
      "brief_justification": "The response correctly identifies the race condition between setnx() and expire(), explains production risks, and provides a valid fix using Redis atomic SET. The code is cut off but the solution is clear."
    },
    {
      "judge_key": "qwen3_8b",
      "judge_name": "Qwen 3 8B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 9.8,
      "brief_justification": "The response thoroughly identifies the race condition in the acquire method, explains production risks, and provides a correct implementation with atomic operations and Lua scripts. The solution addresses all critical issues with clear, actionable fixes."
    },
    {
      "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 the race condition, provides a correct Lua-based solution, and includes detailed analysis of dangers and production considerations. All criteria are fully addressed with clear, actionable insights."
    },
    {
      "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 thoroughly identifies both race conditions, explains their dangers, and provides a correct implementation using atomic Lua scripts. It also includes production best practices, making it highly accurate, complete, and actionable."
    },
    {
      "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 thoroughly identifies the race condition in the original code, explains its dangers, and provides a correct implementation with atomic operations and production considerations. The solution is accurate, complete, and practical."
    },
    {
      "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 thoroughly identifies both race conditions, explains their production risks, and provides a correct implementation with atomic operations. It includes detailed analysis, best practices, and clear code examples that 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": 8.35,
      "brief_justification": "Correctly identifies the race condition between setnx and expire, explains risks, and proposes the atomic SET command with NX/EX flags. However, the response is cut off mid-code, leaving the corrected implementation incomplete. The explanation is clear and logically structured but lacks a full working solution."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the race condition in the original code, explains why it's dangerous, and provides a correct, production-ready implementation using Redis' atomic commands and Lua scripting. It also includes clear explanations of the fixes and best practices."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the race conditions in both acquire and release methods, explains their production dangers, and provides a correct implementation using Redis's atomic SET with NX/EX and a Lua script. It covers all aspects thoroughly and offers practical, well-structured 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 correctly identifies the race condition in the non-atomic setnx/expire sequence, provides a complete and technically sound fix using Lua scripts, explains production dangers in detail, and includes additional production considerations. The explanation is clear, well-structured, and offers practical value with a working implementation."
    },
    {
      "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 both race conditions, explains their dangers, and provides a complete, correct implementation using Redis Lua scripts for atomic operations. It also includes valuable production considerations and maintains excellent clarity throughout."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 10,
      "brief_justification": "The response accurately identifies the race conditions in both acquisition and release, provides a complete corrected implementation with atomic Redis operations and Lua scripting, explains production risks in detail, and includes practical usage examples and additional considerations."
    },
    {
      "judge_key": "qwen3_32b",
      "judge_name": "Qwen 3 32B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 8.8,
      "brief_justification": "The response accurately identifies the race conditions in both acquire and release methods, provides a correct fix using Redis's atomic SET command and Lua scripting, and thoroughly explains production risks. It's well-structured with clear code examples and additional best practices."
    },
    {
      "judge_key": "qwen3_coder_next",
      "judge_name": "Qwen 3 Coder Next",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 9,
      "brief_justification": "The response correctly identifies the race condition between `setnx()` and `expire()` and explains production risks well, but cuts off mid-sentence before completing the corrected implementation. It omits the critical `release()` fix (using Lua script to avoid TOCTOU) and doesn't show the atomic `SET` command fully. Despite strong analysis, incompleteness prevents a perfect score."
    },
    {
      "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 correctly identifies the race condition between `setnx` and `expire`, explains the production risks thoroughly, and provides a correct, production-grade fix using atomic Redis `SET` with `NX`/`PX` and a Lua script for safe release. All aspects—accuracy, coverage, structure, insight, and practical guidance—are excellent."
    },
    {
      "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 evaluation correctly identifies the atomicity bug between `setnx` and `expire`, explains production risks thoroughly, and provides a robust, production-grade fix using Lua scripting with proper token verification, blocking/timeout support, and context manager integration. All aspects are addressed with high technical accuracy and actionable insight."
    },
    {
      "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 both race conditions (non-atomic set+expire and check-then-act in release), explains their production dangers thoroughly, and provides a robust, production-ready fix using Lua scripts for atomicity. It includes additional best practices like token isolation, retry logic, and context manager suggestions, demonstrating deep understanding and practical value."
    },
    {
      "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 evaluation correctly identifies both race conditions (non-atomic setnx+expire and get+delete), explains production dangers thoroughly, and provides a robust, production-grade fix using atomic SET with NX/EX and Lua scripting, along with valuable additional context like watchdogs and context managers."
    },
    {
      "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 both race conditions (non-atomic acquire and release), explains their production dangers thoroughly, and provides a robust, production-ready fix using Redis atomic operations (SET with EX/NX and Lua scripts). It includes additional best practices and a clear comparison table, demonstrating deep understanding of distributed systems principles."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 6.25,
      "brief_justification": "The model correctly identifies the primary race condition and suggests the standard atomic SET fix, but the response is severely truncated mid-code and fails to address the non-atomic release method."
    },
    {
      "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": 8.55,
      "brief_justification": "The response correctly identifies the main race condition (SETNX/EXPIRE separation) and provides the proper fix using atomic SET with NX/EX and Lua scripts for release. However, there's a minor bug in the token generation code (calling uuid4() twice instead of once), and the race condition scenario explanation has slight imprecision. Overall, the implementation is production-ready and well-explained."
    },
    {
      "judge_key": "qwen35_35b_a3b",
      "judge_name": "Qwen 3.5 35B-A3B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 8.15,
      "brief_justification": "The response correctly identifies the two main race conditions (non-atomic setnx+expire and check-then-act in release) and provides a working fix using Lua scripts for atomicity. However, it slightly mischaracterizes Bug 1 as causing simultaneous lock ownership when it actually causes permanent locks. The implementation is production-ready with good structure, though it could explore more edge cases like lock expiration timing and Redlock algorithm considerations."
    },
    {
      "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": 9,
      "brief_justification": "The response correctly identifies both race conditions (non-atomic setnx/expire and get/delete), provides a working fix using atomic SET NX EX and Lua scripts, and includes production considerations. Minor deduction for not mentioning Redlock algorithm alternatives or network partition edge cases, but overall excellent coverage."
    },
    {
      "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 both race conditions (non-atomic acquire with setnx+expire and non-atomic release with get+delete), provides accurate fixes using Redis atomic operations (set with ex+nx, Lua scripts), and includes production-ready enhancements like retry limits and error handling. The explanation is thorough, well-structured, and actionable."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen3_coder_next",
      "respondent_name": "Qwen 3 Coder Next",
      "weighted_score": 8.55,
      "brief_justification": "The response correctly identifies the SETNX+EXPIRE and GET+DELETE race conditions and provides a proper atomic fix using SET NX EX and Lua scripts. Minor issue: the explanation of 'two processes holding lock simultaneously' is slightly misleading - the main acquire bug causes permanent locks, while the release race condition is what could cause simultaneous lock ownership."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_35b_a3b",
      "respondent_name": "Qwen 3.5 35B-A3B",
      "weighted_score": 7.9,
      "brief_justification": "The response correctly identifies the non-atomic acquire issue and provides a proper Lua script fix, but focuses on the deadlock scenario rather than the specific race condition allowing two processes to hold the lock simultaneously (which occurs in the release method's check-then-delete pattern). The implementation is production-ready with good additional considerations."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_122b_a10b",
      "respondent_name": "Qwen 3.5 122B-A10B",
      "weighted_score": 8.8,
      "brief_justification": "The response correctly identifies both race conditions (non-atomic setnx+expire and get+delete) and provides accurate fixes using SET NX EX and Lua scripting. It thoroughly covers production considerations and includes context manager support, though the 'acquired' flag could be more robust for handling natural lock expiration."
    },
    {
      "judge_key": "qwen35_27b",
      "judge_name": "Qwen 3.5 27B",
      "respondent_key": "qwen35_397b_a17b",
      "respondent_name": "Qwen 3.5 397B-A17B",
      "weighted_score": 9.8,
      "brief_justification": "The response correctly identifies both race conditions (non-atomic acquire and release), provides the industry-standard fix using Redis SET with NX/EX and Lua scripts, and thoroughly explains production risks with actionable best practices."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_9b",
      "respondent_name": "Qwen 3.5 9B",
      "weighted_score": 6.35,
      "brief_justification": "The diagnostic analysis of the race condition is accurate and well-structured, but the response is critically truncated before providing the required corrected implementation, rendering it practically unusable."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 8.55,
      "brief_justification": "The response provides the correct industry-standard solution (atomic SET with NX/PX and Lua script) and is well-structured, though it slightly conflates the specific race conditions regarding deadlock versus simultaneous access in its explanation. The code is production-ready and actionable."
    },
    {
      "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": 8.8,
      "brief_justification": "The response correctly identifies the main race conditions (SETNX+EXPIRE non-atomicity and GET+DELETE race in release) and provides the industry-standard fix using SET NX EX and Lua scripts. Minor deduction for unnecessary double UUID generation in token creation and could elaborate more on why SET NX EX is atomic at the Redis protocol level."
    },
    {
      "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": 8.15,
      "brief_justification": "Response correctly identifies race conditions and provides Lua-based fixes, but the acquire Lua script incorrectly uses SET without NX option (should be SET NX EX to prevent overwriting existing locks). The get/delete race in release() is the more critical bug for simultaneous lock ownership, which could be identified more clearly."
    },
    {
      "judge_key": "qwen35_122b_a10b",
      "judge_name": "Qwen 3.5 122B-A10B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 8.6,
      "brief_justification": "The response correctly identifies both race conditions (non-atomic set/expire and check-then-act in release) and provides a proper Lua script-based fix. Minor deductions for not mentioning clock skew issues or multi-Redis-node considerations (Redlock algorithm)."
    },
    {
      "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": 10,
      "brief_justification": "The response accurately identifies both race conditions and provides industry-standard fixes using atomic Redis commands and Lua scripts. The explanation of production risks and additional best practices adds significant value beyond the basic requirements."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen3_8b",
      "respondent_name": "Qwen 3 8B",
      "weighted_score": 9.8,
      "brief_justification": "The response correctly identifies the atomicity issues in both acquisition and release and provides the industry-standard fix using Redis SET NX PX and Lua scripts. It clearly explains the production risks and offers a robust, copy-pasteable solution."
    },
    {
      "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": 6.65,
      "brief_justification": "While the analysis of the original atomicity bug is accurate, the proposed fix contains critical errors in the Lua script (missing 'NX' flag and incorrect truthiness check for integer returns) that render the lock non-functional and unsafe."
    },
    {
      "judge_key": "qwen35_397b_a17b",
      "judge_name": "Qwen 3.5 397B-A17B",
      "respondent_key": "qwen35_27b",
      "respondent_name": "Qwen 3.5 27B",
      "weighted_score": 9.8,
      "brief_justification": "The response accurately identifies atomicity issues in both acquire and release methods and provides a robust Lua-based solution, though it could have noted the simpler modern SET NX EX command for acquisition."
    },
    {
      "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": 9.6,
      "brief_justification": "The response accurately identifies both race conditions and provides industry-standard atomic fixes using SET and Lua scripts. However, the release method contains a minor logic error where the local acquired flag is incorrectly set to True upon successful release."
    }
  ],
  "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)"
  }
}