{ "evaluation_id": "EVAL-20260402-130102", "question_id": "CODE-011", "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": "2026-04-02T13:01:02.430Z", "display_date": "Apr 02, 2026", "winner": { "name": "Claude Sonnet 4.6", "provider": "openrouter", "score": 9.44 }, "avg_score": 8.59, "matrix_size": 84, "models_used": [ { "id": "claude_opus_46", "name": "Claude Opus 4.6", "provider": "openrouter" }, { "id": "gemini_31_pro", "name": "Gemini 3.1 Pro", "provider": "openrouter" }, { "id": "claude_sonnet_46", "name": "Claude Sonnet 4.6", "provider": "openrouter" }, { "id": "grok_420", "name": "Grok 4.20", "provider": "openrouter" }, { "id": "deepseek_v4", "name": "DeepSeek V4", "provider": "openrouter" }, { "id": "gpt_oss_120b", "name": "GPT-OSS-120B", "provider": "OpenAI" }, { "id": "gemini_3_flash", "name": "Gemini 3 Flash Preview", "provider": "Google" }, { "id": "minimax_m25", "name": "MiniMax M2.5", "provider": "openrouter" }, { "id": "mimo_v2_flash", "name": "MiMo-V2-Flash", "provider": "Xiaomi" }, { "id": "gpt_5_4", "name": "GPT-5.4", "provider": "openrouter" } ], "rankings": { "claude_sonnet_46": { "display_name": "Claude Sonnet 4.6", "provider": "openrouter", "average_score": 9.44, "score_count": 9, "min_score": 8.8, "max_score": 10, "rank": 1 }, "gpt_5_4": { "display_name": "GPT-5.4", "provider": "openrouter", "average_score": 9.41, "score_count": 8, "min_score": 8.05, "max_score": 10, "rank": 2 }, "claude_opus_46": { "display_name": "Claude Opus 4.6", "provider": "openrouter", "average_score": 9.27, "score_count": 9, "min_score": 8.4, "max_score": 10, "rank": 3 }, "grok_420": { "display_name": "Grok 4.20", "provider": "openrouter", "average_score": 9.18, "score_count": 7, "min_score": 8.8, "max_score": 9.8, "rank": 4 }, "gemini_3_flash": { "display_name": "Gemini 3 Flash Preview", "provider": "Google", "average_score": 9.08, "score_count": 8, "min_score": 8.6, "max_score": 10, "rank": 5 }, "mimo_v2_flash": { "display_name": "MiMo-V2-Flash", "provider": "Xiaomi", "average_score": 9.02, "score_count": 9, "min_score": 8.45, "max_score": 10, "rank": 6 }, "gpt_oss_120b": { "display_name": "GPT-OSS-120B", "provider": "OpenAI", "average_score": 8.83, "score_count": 9, "min_score": 7.5, "max_score": 10, "rank": 7 }, "minimax_m25": { "display_name": "MiniMax M2.5", "provider": "openrouter", "average_score": 8.68, "score_count": 8, "min_score": 6.85, "max_score": 10, "rank": 8 }, "deepseek_v4": { "display_name": "DeepSeek V4", "provider": "openrouter", "average_score": 7.94, "score_count": 8, "min_score": 5.9, "max_score": 9.8, "rank": 9 }, "gemini_31_pro": { "display_name": "Gemini 3.1 Pro", "provider": "openrouter", "average_score": 5.06, "score_count": 9, "min_score": 1.65, "max_score": 8.8, "rank": 10 } }, "judgments": [ { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.4, "brief_justification": "Correctly identifies both major races, explains the production danger well, and provides a solid fix using atomic SET NX EX and Lua-based conditional delete. Slightly incomplete because it appears truncated at the end and includes a questionable 'single-instance Redlock' phrasing." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 1.65, "brief_justification": "The response is only an incomplete opening statement. It identifies the general area of the bugs but does not actually explain the race, why it is dangerous, or provide a corrected implementation as requested." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 8.8, "brief_justification": "Accurately identifies both key races, especially the ownership-check/delete bug that can lead to overlapping lock holders, and provides a solid fix using atomic SET NX PX and Lua-based release. Clear, practical, and production-oriented. Minor caveat: the extend() semantics reset TTL rather than clearly adding additional time, and it does not discuss broader distributed-lock limitations such as fencing tokens or Redlock tradeoffs." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9, "brief_justification": "Accurately identifies both major races: non-atomic SETNX+EXPIRE and unsafe GET-then-DELETE, explains production impact well, and provides a solid corrected implementation using atomic SET NX PX and Lua-based release. Minor caveat: mentioning Redlock as 'better' is debatable, and the response could discuss lock expiration during long critical sections more explicitly." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 6.05, "brief_justification": "Clear and mostly practical, but it misses the race highlighted in the prompt: non-atomic get-then-delete in release can let one process delete another's newly acquired lock after expiry, causing two holders simultaneously. It correctly fixes release with Lua and improves acquire with atomic SET NX EX, but the explanation focuses mainly on the deadlock/stuck-lock issue rather than the simultaneous-holder bug." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 7.5, "brief_justification": "Accurately identifies the two main atomicity bugs and recommends SET NX PX plus Lua delete. Clear explanation and good production context. However, it introduces some questionable claims/details, the provided code is truncated/incomplete, and the 'production-ready' implementation cannot be used as shown." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.6, "brief_justification": "Accurately identifies the two key atomicity bugs and proposes the standard Redis fix using SET NX PX plus a Lua compare-and-delete. Clear and practical, though it could more explicitly discuss that lease expiry alone means a process may still act after losing the lock and mention fencing tokens/Redlock caveats for full production rigor." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 6.85, "brief_justification": "Accurately identifies both major races and the correct Redis patterns (atomic SET NX EX and atomic Lua-based release), with clear production impact. However, the provided 'correct implementation' is truncated before the Lua release code and final implementation details, so completeness and practical usefulness are reduced." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8.6, "brief_justification": "Accurately identifies the non-atomic SETNX+EXPIRE bug and the unsafe GET+DEL release race, and proposes the standard Redis fixes using SET NX EX and atomic Lua release. Clear and practical, though it misses deeper discussion of lock lease expiry during long critical sections and overstates event-loop concerns for this synchronous code." }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 10, "brief_justification": "The response is exceptional across all dimensions. It correctly identifies both race conditions (non-atomic setnx+expire and non-atomic get+delete), provides precise timeline examples showing how mutual exclusion breaks, explains real-world production consequences thoroughly, and delivers a correct fix using SET NX EX and Lua scripting. The depth is outstanding—it covers the remaining caveat about TTL expiration during long-running tasks, mentions fencing tokens and lock renewal, and provides a " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 2.45, "brief_justification": "The response is truncated and incomplete - it only begins to identify the bugs but never finishes explaining them or provides the corrected implementation. While it correctly starts to identify that there are two bugs (the non-atomic setnx+expire in acquire and the non-atomic get+delete in release), it cuts off before delivering any substantive analysis or fix. The response is essentially unusable as it provides no complete explanation and no corrected code." }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9.6, "brief_justification": "The response correctly identifies both race conditions: the non-atomic setnx+expire in acquire and the non-atomic get+delete in release. The explanations with timelines are crystal clear. The fix uses SET NX PX for atomic acquire and Lua scripts for atomic release, which are the standard correct solutions. The implementation is production-quality with retry_timeout, extend functionality, context manager support, proper logging, and error handling for expired locks. Minor completeness gap: no men" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.35, "brief_justification": "The response correctly identifies both race conditions: the non-atomic SETNX+EXPIRE in acquire() and the check-then-act GET+DELETE in release(). The explanation of why each is dangerous is accurate and well-articulated. The fix uses SET with NX+PX for atomic acquisition and a Lua script for atomic release, which is the standard correct approach. The response also adds practical improvements like blocking/non-blocking acquire, timeout, context manager support, and mentions Redlock for stronger gu" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 9, "brief_justification": "The response correctly identifies the primary race condition (non-atomic setnx + expire) and the secondary race condition in release (non-atomic get + delete). The fix using SET with NX/EX and Lua script for release is the standard correct approach. The explanation of production dangers is clear and accurate. Minor deduction: could have mentioned the release() race condition more explicitly as a separate bug rather than just fixing it silently, and could have discussed Redlock for multi-node Red" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.2, "brief_justification": "The response correctly identifies both critical bugs: the non-atomic SETNX+EXPIRE in acquire and the non-atomic GET+DELETE in release. The explanation of why each is dangerous is accurate and thorough. The fix uses SET NX PX for atomic acquire and a Lua script for atomic release, which are the standard correct approaches. The response goes beyond the minimum by addressing auto-renewal/watchdog threads, exponential backoff with jitter, context manager support, and error handling. The table format" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 9.6, "brief_justification": "The response correctly identifies both race conditions (non-atomic SETNX+EXPIRE and non-atomic GET+DELETE), explains the production dangers clearly with concrete scenarios, and provides the standard correct fix using SET NX PX and a Lua script for release. The explanation is exceptionally well-structured with clear headings, the code is correct and idiomatic, and the key improvements are well-summarized. Minor nitpick: could have mentioned Redlock for multi-node Redis or context manager support," }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.85, "brief_justification": "The response correctly identifies both race conditions (non-atomic SETNX+EXPIRE and non-atomic GET+DELETE), explains production dangers clearly with a helpful table, and provides the correct fix using SET NX EX and a Lua script for release. The explanation is exceptionally well-structured and clear. Minor deductions: the response appears truncated (the Lua script for release is cut off), which affects completeness and usefulness. The correctness is high because everything stated is accurate, but" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 9.2, "brief_justification": "The response correctly identifies the primary race condition (non-atomic setnx + expire), explains the danger clearly with a concrete scenario, and provides the correct fix using SET NX EX and a Lua script for release. The release race condition is also correctly identified and fixed. The explanation is exceptionally well-structured with clear headings and code comments. Minor nit: the scenario description focuses on the deadlock case (expire never runs) rather than the dual-lock-holder case men" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 8.05, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.85, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 10, "brief_justification": "The response perfectly identifies the race conditions, explains them clearly with timelines, and provides a production-ready, robust implementation with excellent additions like Lua scripts, context managers, and TTL extension." }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.35, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 5.9, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 8.1, "brief_justification": "The response correctly identifies the race conditions and provides a robust solution with advanced features like a watchdog and jitter, but the provided code is truncated at the end." }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 10, "brief_justification": "The response perfectly identifies both race conditions, explains the production risks clearly, and provides a robust, industry-standard solution using atomic Redis operations and Lua scripting." }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 7.75, "brief_justification": "The response correctly identifies both race conditions and provides an excellent explanation of the risks and conceptual fixes. However, it cuts off before providing the Lua script for the release method, impacting completeness and usefulness." }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 9.35, "brief_justification": "" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.8, "brief_justification": "Excellent response that correctly identifies both race conditions (non-atomic setnx+expire and non-atomic get+delete), explains the exact failure scenarios with concrete timelines, provides a correct implementation using SET NX EX and Lua scripting, and goes beyond to mention caveats like TTL expiry during long operations, fencing tokens, and lock renewal. The context manager addition and production impact discussion add significant practical value. Depth is very high though could mention Redloc" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.8, "brief_justification": "Exceptional response that correctly identifies both race conditions (non-atomic acquire and non-atomic release), provides precise failure scenario timelines, and delivers a production-quality fix using SET NX EX and Lua scripting. The implementation includes bonus features like lock extension, context manager support, max_wait parameter, and meaningful warnings when lock expiry is detected. Code is well-commented and immediately usable." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 4.35, "brief_justification": "The response is cut off mid-sentence and incomplete. It correctly identifies there are two bugs (acquire race between setnx and expire, and release check-then-delete race), but the actual explanation and fix are never provided. The response starts well by identifying both issues but delivers no actionable content, no code fix, and no complete explanation. Severely incomplete." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.8, "brief_justification": "Accurately identifies both race conditions (SETNX+EXPIRE non-atomicity and GET+DEL check-then-act), provides a correct fix using atomic SET NX PX and Lua script for release, includes context manager support, blocking/timeout options, and production guidance. Minor issue: the token comparison in release may need encoding handling (bytes vs string in redis-py), but overall excellent response." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 8.15, "brief_justification": "The response correctly identifies the setnx/expire race condition and provides a solid fix using atomic SET with nx+ex flags and a Lua script for atomic release. However, it misses the second race condition in the release() method (check-then-delete is non-atomic), which is actually the more subtle bug mentioned in the prompt - though the Lua script fix addresses it implicitly. The response also doesn't mention the token comparison issue (bytes vs string in Python redis client). Overall well-str" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9, "brief_justification": "The response correctly identifies both race conditions (non-atomic SETNX+EXPIRE and non-atomic GET+DELETE), explains them clearly with a table, and provides a comprehensive fix using SET NX PX and a Lua script for atomic release. The implementation includes watchdog renewal, exponential backoff, context manager support, and error handling. The response appears to be cut off at the end (the eval call is incomplete), which slightly reduces completeness, but the core concepts and most of the implem" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.8, "brief_justification": "Excellent identification of both race conditions with clear explanations. The fix using atomic SET with NX/PX and Lua script for release is correct and production-ready. The scenario walkthrough for the check-then-act race is slightly muddled but the core point is valid. Minor nitpick: doesn't mention Redlock for multi-node setups, but that's beyond the scope of the question." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 9, "brief_justification": "The response correctly identifies both race conditions (SETNX/EXPIRE non-atomicity and GET/DELETE non-atomicity), explains their production consequences clearly, and provides a correct fix using SET NX EX and a Lua script for atomic release. The table summarizing dangers is helpful. Minor deduction for the truncated release() implementation in the final code block, but the explanation is otherwise thorough and accurate." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8.8, "brief_justification": "Excellent response that correctly identifies the primary bug (non-atomic setnx+expire), explains the deadlock risk clearly, and provides a proper fix using SET NX EX. Also correctly identifies and fixes the secondary race condition in release() using a Lua script. The explanation of why Lua scripts are atomic in Redis is accurate and insightful. Minor deduction: the acquire() retry logic is slightly awkward (tries once before the loop, then loops), and the response could mention context managers" }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9, "brief_justification": "The response accurately identifies both the non-atomic SETNX+EXPIRE and GET+DELETE races, explains the production risks clearly with examples, and provides a correct, improved implementation using atomic SET and Lua script. It also covers caveats like lock expiration and adds useful enhancements like context manager support." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9, "brief_justification": "The response accurately identifies the two main race conditions with clear timelines, provides a robust fixed implementation using atomic SET and Lua scripts, adds useful features like context manager and extend, and explains production risks effectively." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 5.65, "brief_justification": "The response correctly identifies the release() race condition but is incomplete as it cuts off mid-sentence without providing the full explanation or the promised correct implementation. It mentions two bugs but only elaborates on one partially." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9, "brief_justification": "The response accurately identifies the two main race conditions (non-atomic setnx+expire and check-then-act release), explains the production risks clearly with timelines, and provides a robust fixed implementation using atomic SET NX PX and Lua scripts. It adds valuable features like extend, context managers, and logging while maintaining high clarity and depth." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 8.8, "brief_justification": "The response correctly identifies a real bug (though not the one stated in the query), explains the deadlock risk accurately, and provides a solid, improved implementation using atomic SET and Lua script. It addresses safety comprehensively with production advice. Minor deduction as it didn't pinpoint the exact race condition mentioned in the query (release without Lua being racy under concurrent clients)." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 8.65, "brief_justification": "The response accurately identifies the race conditions in acquire (non-atomic SETNX+EXPIRE) and release (non-atomic GET+DEL), explains production dangers well, and provides a robust fixed implementation using atomic SET NX PX and Lua script. Minor deduction for incomplete code snippet at the end and slight overstatement of races in original acquire table." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.6, "brief_justification": "Accurately identifies key race conditions and provides a correct, atomic fix using SET NX PX and Lua script. Thorough explanation of production risks and improvements, with clear code." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.8, "brief_justification": "The response accurately identifies the core race conditions, explains their production risks clearly with a table, and provides a correct, improved implementation using atomic SET and Lua (though Lua script is incomplete in the provided text). High clarity and usefulness with good depth on atomicity." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8.6, "brief_justification": "The response accurately identifies the setnx+expire race condition, explains production risks well, and provides a solid fix using atomic SET and Lua script. Minor deduction for not mentioning that the original acquire never returns False and for slightly overcomplicating the acquire retry logic, but overall excellent." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.6, "brief_justification": "Comprehensive explanation of race conditions, clear fixes, and practical implementation with context manager." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.8, "brief_justification": "The response thoroughly identifies and fixes critical race conditions, provides a correct implementation, and explains the dangers clearly with practical examples." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 8.6, "brief_justification": "Accurate identification of critical bugs, thorough explanation, and practical fix provided." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9.6, "brief_justification": "Detailed explanation of race conditions and a robust, production-ready implementation with atomic operations." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.8, "brief_justification": "Comprehensive and accurate explanation of the bug, with a correct implementation and additional best practices." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 10, "brief_justification": "Comprehensive, accurate, and clear explanation with a production-ready implementation." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 9.6, "brief_justification": "Thoroughly explains the race conditions, provides a correct implementation, and clearly outlines the dangers in production." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 9.6, "brief_justification": "Accurate, thorough, and practical with clear explanations and fixes." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 9.6, "brief_justification": "Thoroughly explains the bug, its dangers, and provides a correct, atomic implementation with clear reasoning." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 8.8, "brief_justification": "Accurately identifies both atomicity issues, explains production risks, and offers a solid, practical Redis lock implementation with context manager and caveats." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.8, "brief_justification": "Accurately identifies both race conditions, offers a solid atomic fix with SET and Lua script, explains production risks, and provides a practical, well-structured implementation." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 3.4, "brief_justification": "The answer starts to identify bugs but is incomplete, missing a full explanation of why it's dangerous, and does not provide a complete corrected implementation. The partial explanation is somewhat clear but lacks depth and practical utility." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 8.8, "brief_justification": "Accurately identifies the non‑atomic setnx/expire and get/delete bugs, explains why they cause deadlocks and double‑ownership, and provides a solid production‑ready fix using SET with NX+PX and Lua scripts, with clear code and practical usage examples." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 8, "brief_justification": "Accurately spots the non‑atomic setnx/expire race, offers a proper atomic SET with NX/EX and Lua‑based release, explains production risks and adds practical advice, though it focuses on deadlock rather than simultaneous lock holding." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.6, "brief_justification": "Accurately identifies the non-atomic setnx/expire and check-then-delete races, explains production risks, and offers a proper atomic SET+PX and Lua release solution." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8.6, "brief_justification": "Accurately identifies the setnx/expire race and release race, offers atomic SET and Lua release, explains why it's risky, and gives clear, practical code." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 10, "brief_justification": "The response is exceptionally thorough, identifying both the obvious and subtle race conditions. It provides a production-ready fix using Lua scripts and atomic SET commands, explains the consequences of the bugs, and even includes advanced considerations like fencing and lock renewal." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 10, "brief_justification": "The response is exceptional. It correctly identifies both the acquisition and release race conditions, provides clear timeline visualizations of the failures, and offers a production-ready implementation using atomic SET commands and Lua scripts. It even includes bonus features like a context manager and an extend method." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 8.1, "brief_justification": "The model correctly identifies the primary race condition in the release method and the secondary deadlock risk in the acquire method. However, the response is truncated and does not provide the promised 'correct implementation' or the full explanation, significantly impacting completeness and usefulness." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 10, "brief_justification": "The response is exceptionally high quality. It correctly identifies both the non-atomic acquisition (leading to potential deadlocks) and the non-atomic release (leading to accidental deletion of other processes' locks). The fix uses industry-standard best practices: the atomic SET command with NX/PX flags and a Lua script for the release. It also adds useful production features like a context manager and a lock extension method." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 9.8, "brief_justification": "The response correctly identifies the atomicity issue in both the acquire and release methods. It provides the industry-standard fix using the atomic SET command and a Lua script for the release, which prevents the second race condition (the 'check-then-delete' bug) which the original code also suffered from." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.6, "brief_justification": "The response correctly identifies both the atomicity bug in the acquisition phase (SETNX/EXPIRE) and the race condition in the release phase (GET/DELETE). It provides a high-quality, production-ready implementation using the atomic SET command and a Lua script for release, including advanced features like a watchdog thread and exponential back-off." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 10, "brief_justification": "The response correctly identifies both race conditions (the non-atomic acquisition and the non-atomic release). It provides a high-quality explanation of the production risks and a robust, industry-standard fix using atomic SET parameters and a Lua script for release." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 10, "brief_justification": "The response perfectly identifies the atomicity bug in the original code, explains the deadlock risk, and provides the industry-standard fix using atomic SET and Lua scripts for release. It also correctly identifies the risk of the original release method." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 10, "brief_justification": "Excellent response that correctly identifies both race conditions (setnx+expire non-atomic and get+delete non-atomic), provides detailed production consequences with concrete examples, offers working code with atomic operations (SET NX EX and Lua script), and includes important caveats about TTL and long-running tasks. Well-structured with clear explanations and a context manager implementation." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.45, "brief_justification": "Accurately identifies both race conditions (non-atomic setnx+expire and non-atomic get+delete) with correct fixes using SET with NX/EX and Lua scripts. Well-structured with timeline diagrams. Slightly incomplete ending (production table truncated) but core content is thorough and actionable." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 2.5, "brief_justification": "Response is incomplete - it begins to identify bugs but cuts off before explaining them or providing the correct implementation. No actual fix or useful guidance is delivered." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9.8, "brief_justification": "Excellent response that correctly identifies both race conditions (non-atomic acquire and non-atomic release), explains the production dangers clearly with timelines, and provides a complete, production-ready implementation using Redis SET with NX/PX and Lua scripts for atomic operations. Well-structured with clear code examples and additional useful features." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.8, "brief_justification": "Correctly identifies the GET-then-DELETE race condition as the primary bug and explains the SETNX+EXPIRE issue. Provides proper atomic fix using SET with NX/PX and Lua script. Clear explanations, actionable code, and mentions real-world production dangers and alternatives like Redlock." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 7.8, "brief_justification": "Correctly identifies the setnx/expire race condition and provides a proper fix using atomic Redis operations. The Lua script for release is also correct. However, the response could be more comprehensive by explicitly mentioning the race condition in the original release() method. Well-structured with good practical recommendations for production use." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 8.6, "brief_justification": "Accurately identifies both race conditions (non-atomic SETNX+EXPIRE and GET+DELETE). Provides correct fixes using SET NX PX and Lua script. Well-structured explanation with production-ready implementation including auto-renewal, context managers, and error handling. Slight deduction for incomplete code snippet at end." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.8, "brief_justification": "Accurately identifies both race conditions (non-atomic setnx+expire in acquire and get+delete in release), explains production dangers (data corruption, deadlocks), and provides correct atomic implementation using Redis SET NX/PX and Lua script. Well-structured with clear code examples." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8.45, "brief_justification": "Correctly identifies the setnx/expire race condition, provides atomic fix using SET with NX/EX options, and implements safe release with Lua script. Explains production dangers well. Minor deduction for retry logic timeout being same as lock timeout (could be configurable)." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.35, "brief_justification": "Accurately identifies both race conditions, provides a correct atomic implementation with Lua scripts, and explains production risks clearly." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 8.8, "brief_justification": "Accurately identifies two bugs, explains danger, and provides a correct implementation with atomic operations." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9.35, "brief_justification": "Accurate identification of race conditions, correct atomic fixes with Lua scripts, and comprehensive production-ready implementation with context manager and extension support." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.15, "brief_justification": "Accurately identifies the race condition, explains production risks, provides a correct atomic implementation with Lua script, and offers advanced alternatives." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 8.8, "brief_justification": "Accurate identification of race conditions, provides correct atomic implementation with Lua script and renewal, but response is cut off mid-code." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.6, "brief_justification": "Accurately identifies two critical race conditions, explains production dangers, and provides a correct atomic implementation using SET NX EX and Lua script for 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)" } }