{ "evaluation_id": "EVAL-20260402-124935", "question_id": "CODE-009", "question_text": "This Python application has a memory leak. Find it and explain the fix.\n\n```python\nimport threading\nimport time\nfrom functools import lru_cache\n\nclass EventProcessor:\n _instances = []\n \n def __init__(self, name):\n self.name = name\n self.callbacks = []\n self._lock = threading.Lock()\n EventProcessor._instances.append(self)\n \n def register_callback(self, func):\n self.callbacks.append(func)\n \n @lru_cache(maxsize=10000)\n def process(self, event_data):\n results = []\n for callback in self.callbacks:\n result = callback(event_data)\n results.append(result)\n return tuple(results)\n \n def __del__(self):\n print(f\"Processor {self.name} deleted\")\n\ndef create_processor_for_request(request_id):\n processor = EventProcessor(f\"processor_{request_id}\")\n processor.register_callback(lambda x: x.upper())\n processor.register_callback(lambda x: len(x))\n return processor\n\n# Simulated request handling\ndef handle_request(request_id, data):\n processor = create_processor_for_request(request_id)\n return processor.process(data)\n\n# This runs for hours...\nfor i in range(1000000):\n result = handle_request(i, f\"event_data_{i}\")\n time.sleep(0.001)\n```", "category": "code", "timestamp": "2026-03-10T00:00:00.000Z", "display_date": "Mar 10, 2026", "winner": { "name": "GPT-5.4", "provider": "openrouter", "score": 9.54 }, "avg_score": 8.072, "matrix_size": 89, "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": { "gpt_5_4": { "display_name": "GPT-5.4", "provider": "openrouter", "average_score": 9.54, "score_count": 9, "min_score": 8.8, "max_score": 10, "rank": 1 }, "grok_420": { "display_name": "Grok 4.20", "provider": "openrouter", "average_score": 9.06, "score_count": 9, "min_score": 8.4, "max_score": 10, "rank": 2 }, "claude_opus_46": { "display_name": "Claude Opus 4.6", "provider": "openrouter", "average_score": 8.81, "score_count": 9, "min_score": 7.55, "max_score": 10, "rank": 3 }, "claude_sonnet_46": { "display_name": "Claude Sonnet 4.6", "provider": "openrouter", "average_score": 8.69, "score_count": 8, "min_score": 6.75, "max_score": 10, "rank": 4 }, "gpt_oss_120b": { "display_name": "GPT-OSS-120B", "provider": "OpenAI", "average_score": 8.46, "score_count": 9, "min_score": 5.3, "max_score": 9.8, "rank": 5 }, "gemini_3_flash": { "display_name": "Gemini 3 Flash Preview", "provider": "Google", "average_score": 8.46, "score_count": 9, "min_score": 7.8, "max_score": 9.6, "rank": 6 }, "deepseek_v4": { "display_name": "DeepSeek V4", "provider": "openrouter", "average_score": 7.55, "score_count": 9, "min_score": 6.35, "max_score": 9.15, "rank": 7 }, "minimax_m25": { "display_name": "MiniMax M2.5", "provider": "openrouter", "average_score": 7.11, "score_count": 9, "min_score": 4.8, "max_score": 9.55, "rank": 8 }, "gemini_31_pro": { "display_name": "Gemini 3.1 Pro", "provider": "openrouter", "average_score": 6.62, "score_count": 9, "min_score": 3.3, "max_score": 9.25, "rank": 9 }, "mimo_v2_flash": { "display_name": "MiMo-V2-Flash", "provider": "Xiaomi", "average_score": 6.42, "score_count": 9, "min_score": 3.65, "max_score": 9.6, "rank": 10 } }, "judgments": [ { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.8, "brief_justification": "Accurately identifies the two main memory leaks (_instances list and lru_cache on instance method), provides clear explanations with code examples, and offers practical fixes including weak references and per-instance caching. Well-structured with good depth on why the leaks occur." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 6.75, "brief_justification": "Correctly identifies two memory leaks but response is cut off mid-sentence, leaving the explanation incomplete and missing fixes." }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.8, "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": 6.75, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.5, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 6.95, "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": 6.1, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.5, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 4.8, "brief_justification": "" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 3.65, "brief_justification": "" }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 8.6, "brief_justification": "Accurately identifies all three memory leaks with correct mechanisms. The fixes are sound and well-explained. Minor imprecision on lru_cache class-level description but overall analysis is correct. Clear structure with tables enhances readability." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 6.45, "brief_justification": "Identifies the _instances list as a leak but misses the primary cause (lambdas creating reference cycles preventing GC). The lru_cache diagnosis is incorrect as the method is defined on the class, not per-instance. Fixes are partial and don't address the root cause of the actual memory leak." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 7.95, "brief_justification": "Accurately identifies the main leak in the class-level _instances list and correctly explains the lru_cache self-retention issue. However, calling the lambdas a separate memory leak is misleading, and saying never use @lru_cache on instance methods is too absolute. Clear, thorough, and offers practical fixes." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 3.3, "brief_justification": "Correctly identifies the primary leak from the class-level _instances list and hints at lru_cache implications, but the response is truncated and fails to explain the secondary issue or provide fixes, making it incomplete and of limited practical value." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 7.95, "brief_justification": "Clearly explains the main real leaks: the class-level _instances list and lru_cache on an instance method pinning self. However, calling the lambdas a distinct leak is overstated and the proposed per-instance cached bound method can itself create self-referential cycles; cache_clear in __del__ is also not an ideal fix. Still, the answer is structured, mostly accurate, and practically helpful." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.6, "brief_justification": "Correctly identifies the primary leak as the class-level _instances list retaining strong references. Also usefully notes the lru_cache issue on an instance method, though calling it a second retention path is a bit overstated since the instance list is already sufficient to leak; still, the recommendation to remove or redesign the cache is sound." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 6.5, "brief_justification": "Correctly identifies the main leak as the growing class-level _instances list and suggests WeakSet/removal. However, it incorrectly claims the lambdas create circular references, and it underexplains that lru_cache on an instance method also keeps references to self via cache keys, which can retain many instances until eviction. Clear and fairly actionable overall." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 5.3, "brief_justification": "Clear and fairly thorough, but it contains a major technical error: functools.lru_cache on an instance method is not per-instance; it creates a shared cache on the function that includes self in the key, which itself can retain instances. The proposed weakref and cache_clear fixes are partly useful, but the explanation of how the leak works is significantly inaccurate." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.2, "brief_justification": "Accurately identifies the main leak via the class-level _instances list and correctly explains the lru_cache-on-instance-method retention issue. Clear structure and practical fixes, though the revised caching approach is somewhat questionable because callbacks are newly created lambdas per request, limiting cache value and still allowing churn." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 5.75, "brief_justification": "Clearly explains the main leak from the class-level _instances list, but it incorrectly claims each instance gets its own lru_cache; the method-level cache is shared and can retain self references, which is the real cache-related issue. Proposed fixes are partly misguided and inconsistent, though the response is readable and offers some practical redesign ideas." }, { "judge_key": "gpt_5_4", "judge_name": "GPT-5.4", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 4.75, "brief_justification": "Clearly written, but it misses the primary leak: the class-level _instances list retains every EventProcessor forever. The lru_cache on an instance method can retain up to maxsize instances, but does not grow indefinitely beyond that. The proposed staticmethod fix is not the best remedy and still leaves _instances leaking; it also changes caching semantics and may cache on callback tuples unnecessarily." }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.8, "brief_justification": "The response correctly identifies both memory leak sources: the class-level _instances list that grows unboundedly and the lru_cache on an instance method that retains self references. The explanation of why __del__ never fires is accurate. The fixes are all correct—WeakSet for instance tracking, removing lru_cache, and the best-practice suggestion of reusing a single processor. The response is exceptionally well-structured with clear headings, code examples, and a concise summary. The depth is " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 5.3, "brief_justification": "The response correctly identifies the two main memory leaks (_instances list and lru_cache), but the answer is incomplete - it cuts off mid-sentence during the explanation of the lru_cache issue. The first leak is well explained, but without completing the lru_cache explanation and providing fixes for both issues, the response falls short on completeness, depth, and usefulness. The lru_cache on an instance method is particularly subtle (it holds references to self, preventing GC even if _instanc" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 8.95, "brief_justification": "The response correctly identifies the two primary memory leaks (_instances list and lru_cache on instance method) and explains them well. Leak 3 (lambdas) is somewhat overstated — the lambdas here don't actually capture the processor or create reference cycles on their own, and the response half-acknowledges this but still labels it a 'leak.' The fix is well-structured and practical: WeakSet for _instances, per-instance cache, and cache_clear in __del__. However, the per-instance cache approach " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.2, "brief_justification": "The response correctly identifies both major memory leak sources: the class-level _instances list and the lru_cache on an instance method (where self becomes part of the cache key, preventing GC). The explanation of why __del__ never fires is accurate. The fixes are practical and well-structured. Minor note: the response could have emphasized more strongly that the lru_cache issue is itself a full memory leak (not just 'makes it worse'), since even without _instances, the lru_cache would retain " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 6.35, "brief_justification": "The response correctly identifies the `_instances` list as a major memory leak and proposes valid fixes (removing it or using WeakSet). However, it significantly underestimates the `lru_cache` issue: since `lru_cache` is an instance method, `self` is part of the cache key, meaning every unique processor instance with unique event data creates a new cache entry that holds a strong reference to the processor—this is arguably the most critical leak, not a 'secondary issue.' The claim about lambdas " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.35, "brief_justification": "The response correctly identifies both memory leak sources: the class-level `_instances` list holding strong references and the `@lru_cache` on an instance method. The explanation of why each causes a leak is accurate and detailed. The fix using `weakref.WeakSet` and `cache_clear()` is appropriate. One minor nuance: the explanation of lru_cache on instance methods could have been slightly more precise about how lru_cache works with `self` as a key (it keeps `self` alive as a cache key, creating " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.2, "brief_justification": "The response correctly identifies both major memory leaks: the class-level _instances list and the lru_cache on an instance method capturing self. The explanation of why lru_cache on instance methods is problematic is mostly accurate, though the description that the cache is 'shared across the class definition' is slightly imprecise—in Python 3, lru_cache on an instance method actually creates a single cache at the class level where self is part of the key, which is correctly noted but could be " }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 5.05, "brief_justification": "The response correctly identifies the _instances list leak but mischaracterizes the lru_cache issue. The lru_cache decorator on a method means `self` is part of the cache key, so each instance's references are held in the cache, preventing GC even if removed from _instances. This is a critical leak the response doesn't properly explain. The fix is also problematic: it still creates new processors per request (modulo naming doesn't help), the lru_cache is still on the method with the same fundame" }, { "judge_key": "claude_opus_46", "judge_name": "Claude Opus 4.6", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 5.45, "brief_justification": "The response correctly identifies the lru_cache on an instance method as one memory leak source, but misses the most obvious and arguably primary leak: `EventProcessor._instances = []` which is a class-level list that appends every instance and never removes them, preventing ALL instances from being garbage collected regardless of the cache. The proposed fix (static method with callbacks tuple) is problematic - each request creates new lambdas, so the tuple of lambdas will be unique each time, m" }, { "judge_key": "gemini_31_pro", "judge_name": "Gemini 3.1 Pro", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 10, "brief_justification": "The response perfectly identifies both the primary memory leak (class-level list) and the subtle secondary retention issue (lru_cache on an instance method). It provides clear explanations, accurate fixes, and an excellent architectural improvement." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.35, "brief_justification": "The response correctly identifies both memory issues: the primary leak from `_instances` holding strong references and the secondary issue of `lru_cache` on instance methods caching `self`. The explanation is thorough, well-structured, and includes multiple fix options ranging from minimal (weakref) to architectural (shared processor). The lru_cache issue explanation is accurate and nuanced. Minor point: could have mentioned that lambdas in callbacks also create closure references, but this is a" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.75, "brief_justification": "Excellent analysis identifying the two primary leaks (class-level _instances list and lru_cache holding strong references to self). The explanation of lru_cache on instance methods is accurate and insightful. Minor issue: the 'lambda closures' as a third leak is somewhat misleading since lambdas themselves aren't a distinct leak source here. The fix is practical and well-explained, though the per-instance dict cache lacks LRU eviction (unbounded growth possible). The summary table and key insigh" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 5.9, "brief_justification": "The response correctly identifies the primary memory leak (_instances list holding strong references) and begins to identify the secondary lru_cache issue, but the response is cut off mid-sentence and never completes the explanation of the lru_cache problem or provides any fix/solution. The incomplete response significantly reduces completeness and usefulness scores." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9, "brief_justification": "Correctly identifies the primary leak (_instances list holding strong references) and the secondary lru_cache issue. Provides multiple fix options with clear code examples. The explanation of why __del__ rarely runs is accurate. Minor gap: doesn't fully explain the lru_cache/self interaction (lru_cache on instance methods is problematic because self is unhashable by default or creates unbounded cache growth per instance), but overall excellent analysis." }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 7.75, "brief_justification": "The response correctly identifies the primary memory leak (_instances list accumulation) and provides good fixes. However, it overstates the circular reference issue with lambdas - the lambdas don't actually create circular references with the processor since they don't reference the processor object. The lru_cache issue is also more significant than described: since lru_cache is an instance method but bound at the class level, it actually holds references to all processor instances that have ca" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.2, "brief_justification": "The response correctly identifies both memory leak sources: the strong reference list and the lru_cache on instance methods. The explanation is thorough, well-structured, and provides multiple fix options with clear rationale. The fixed code example is practical and the summary table adds clarity. Minor note: the lru_cache on an instance method actually creates a single class-level cache (not per-instance) in Python, which means `self` is part of the cache key and prevents GC of instances - this" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.4, "brief_justification": "The response correctly identifies both memory leaks - the global _instances list and the lru_cache holding references to self. The explanation is clear and well-structured. The fix for leak #1 is solid. The fix for leak #2 is creative but has a subtle issue: lambdas are not hashable in a way that makes them useful cache keys (each lambda is a unique object), so the static method cache would essentially never hit. The response does acknowledge this limitation at the end, which shows good awarenes" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 6.8, "brief_justification": "The response correctly identifies the _instances list as the primary leak and the lru_cache as secondary. However, the fix for Leak #1 is incomplete/incorrect - simply capping the list still doesn't remove old references properly, and the 'fix' for processor reuse (modulo-based) introduces a new bug: each time a processor with the same modulo ID is created, it appends MORE callbacks (lambda registrations accumulate). The lru_cache on an instance method still holds a reference to `self` via the b" }, { "judge_key": "claude_sonnet_46", "judge_name": "Claude Sonnet 4.6", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 6, "brief_justification": "The response identifies some real issues but misses the primary memory leak: `EventProcessor._instances` is a class-level list that permanently accumulates every instance ever created, preventing garbage collection entirely. The lru_cache issue with `self` is a secondary concern (and the explanation of it is partially correct - lru_cache on instance methods does hold references to self, but the maxsize=10000 means it's bounded, not indefinitely growing). The proposed fix (staticmethod + passing " }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9, "brief_justification": "Accurately identifies both the strong reference in _instances and the lru_cache retention of self. Provides multiple practical fixes including weakref and design-level reuse. Thorough, well-structured, and highly actionable." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 7.55, "brief_justification": "The response correctly identifies the _instances list and lru_cache issues as primary leaks with good explanations and a reasonable fix. However, it incorrectly claims three leaks (lambdas are not a leak here) and the provided fix still has the same lru_cache problem if reapplied; also overstates that __del__ will never fire. Overall solid analysis but with some inaccuracies." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 5.85, "brief_justification": "Identifies the main _instances leak accurately but the response is incomplete (cuts off mid-sentence) and misses the actual lru_cache-related issue with bound methods/lambdas. Good structure and clarity on the part it covers." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 6.6, "brief_justification": "Identifies main issues like _instances list and lambdas causing cycles, but incorrectly claims lru_cache on instance method holds event data (it doesn't) and that cache is secondary. The primary leak is actually the unbound lru_cache holding strong references to all unique EventProcessor instances forever. Fixes are partially right but incomplete." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 8.8, "brief_justification": "The response accurately identifies the two main memory leak sources (_instances list and per-instance lru_cache), provides correct explanations, and offers multiple practical fixes including weakref and cache_clear. Minor nit: lru_cache on instance method doesn't truly create a 'per-instance cache' in the way described (it's on the function, with self as part of the key), but the overall diagnosis and solutions remain valid and effective." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 7.8, "brief_justification": "Response correctly identifies the _instances list as a major leak and provides a solid explanation and fix for the lru_cache on instance method issue. However, the claim that lru_cache holds a permanent reference to self preventing GC is technically inaccurate in CPython (cache keys use weakrefs internally); the real issue is cache bloat from unique per-instance tuples of lambdas. The suggested fix works but is overly complex for the actual problem." }, { "judge_key": "grok_420", "judge_name": "Grok 4.20", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 6.05, "brief_justification": "The response misidentifies the root cause (lru_cache on bound method does not keep instances alive due to weakref in cache; the real leak is _instances list + __del__ preventing GC). The proposed staticmethod fix is unnecessary and introduces new issues (lambdas aren't reliably hashable). Some explanations are inaccurate." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.6, "brief_justification": "Accurate, thorough, and actionable with excellent depth." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.6, "brief_justification": "Accurate, thorough, and actionable with clear fixes." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 9.25, "brief_justification": "Accurate identification of both memory leaks with clear explanations." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 9.8, "brief_justification": "Comprehensive analysis with clear fixes and explanations." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.4, "brief_justification": "Accurate identification of the memory leak, thorough explanation, clear and actionable fixes, and insightful additional recommendations." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.6, "brief_justification": "Accurate, thorough, and actionable with clear explanations." }, { "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": "Accurate, thorough, and actionable fix with clear explanation of both leaks and solutions." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.8, "brief_justification": "Accurate identification of leaks with clear fixes and additional design recommendation." }, { "judge_key": "deepseek_v4", "judge_name": "DeepSeek V4", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 9.6, "brief_justification": "Accurate diagnosis and solution with clear explanation." }, { "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 the list and lru_cache retention issues, explains why they leak, and offers clear, practical fixes and design improvements." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 8.6, "brief_justification": "Accurately identifies the main leaks, especially the class-level _instances list and lru_cache on an instance method, and offers clear, actionable fixes with good explanations and code examples." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 5.55, "brief_justification": "Identifies the main leak correctly but the answer is cut off, missing full explanation and fix for the lru_cache issue, reducing completeness, clarity, depth, and practical usefulness." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "claude_sonnet_46", "respondent_name": "Claude Sonnet 4.6", "weighted_score": 8.1, "brief_justification": "Identifies the main memory leaks and offers solid fixes, but overstates the lambda issue and misses some nuances about __del__ reliability." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.6, "brief_justification": "Accurately identifies the class-level list and lru_cache as leak sources, explains why they retain objects, and offers clear, practical fixes with weak references and cache redesign." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 7.5, "brief_justification": "Identifies the main leak (instance list) and offers practical fixes, but incorrectly claims lambdas cause circular references, affecting factual accuracy." }, { "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 both the global list and lru_cache issues, explains why they leak, and offers clear, practical code fixes; well-structured and insightful." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.2, "brief_justification": "Accurately identifies the _instances list leak and offers practical fixes, with clear explanations and useful code examples, though the lru_cache point is slightly overstated." }, { "judge_key": "gpt_oss_120b", "judge_name": "GPT-OSS-120B", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 7.45, "brief_justification": "Accurately identifies the lru_cache issue and offers a workable fix, but overlooks the _instances list that also causes a leak, limiting completeness and overall depth." }, { "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 correctly identifies both the obvious memory leak (the class-level list) and the more subtle one (lru_cache on an instance method). It provides clear explanations, multiple fix options, and a best-practice design recommendation." }, { "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 exceptionally accurate and thorough. It correctly identifies the primary leak (the class-level list) and the more subtle, advanced leak involving @lru_cache on instance methods, which is a common pitfall in Python. The provided fix is idiomatic and explains the underlying mechanics perfectly." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 9.25, "brief_justification": "The response correctly identifies the primary memory leak (the class-level list) and correctly identifies the secondary issue with lru_cache on instance methods. Although the response was cut off, the analysis provided is highly accurate and insightful." }, { "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 correctly identifies all three sources of memory leaks, including the subtle lru_cache instance method issue. The provided fix is idiomatic and robust." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 10, "brief_justification": "The response correctly identifies the primary memory leak (the class-level list) and the secondary issue (lru_cache on an instance method). It provides clear, actionable fixes including the use of WeakSet and explains why the original code prevents garbage collection." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 9.15, "brief_justification": "The response correctly identifies the primary leak (the class-level list) and the secondary leak (the LRU cache on an instance method). It provides a clear, working fix and explains the underlying GC issues well." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.8, "brief_justification": "The response correctly identifies both the primary leak (the class-level list) and the secondary issue (the instance-level LRU cache). It provides multiple valid solutions, including the use of weakref and cache clearing, and explains the mechanics of the leak clearly." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 9.55, "brief_justification": "The response correctly identifies both the primary leak (the class-level list) and the secondary inefficiency (per-instance LRU cache). The fix provided is practical and the explanation of why the original code failed is very clear." }, { "judge_key": "gemini_3_flash", "judge_name": "Gemini 3 Flash Preview", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 6.8, "brief_justification": "The response correctly identifies that lru_cache on an instance method causes a leak because 'self' is cached. However, it misses the most obvious leak: the '_instances' class list which appends every instance and never removes them. Furthermore, the proposed fix of caching a tuple of lambdas is technically flawed because each lambda created in 'create_processor_for_request' is a unique object, meaning the cache will never hit and will grow to its max size anyway." }, { "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 memory leak sources (_instances list and lru_cache on instance method), explains why they cause retention, provides multiple actionable fixes including WeakSet and redesign, and includes clear code examples throughout." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 8.4, "brief_justification": "Accurately identifies the class-level _instances list as the primary leak source with correct explanation of strong references preventing GC. Provides two solid fix options and correctly notes the lru_cache issue. Well-structured with clear code examples. Slight depth deduction for not fully exploring all implications of the lru_cache on instance methods." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 8.55, "brief_justification": "Accurately identifies the primary memory leak (unbounded _instances list) and provides multiple valid solutions. Thorough coverage includes LRU cache issues and circular references. Well-structured with clear explanations and complete fixed code. Minor overstatement on lambda circular references but overall technically sound and highly actionable." }, { "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 memory leak sources (class-level list and per-instance lru_cache) with clear explanations and provides multiple practical fixes including a complete working solution." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8, "brief_justification": "Correctly identifies both memory leaks (global _instances list and lru_cache holding self references). Provides a working fix with clear explanation. Minor deduction for completeness: doesn't fully address that the caching is fundamentally ineffective since each request creates unique lambdas, making cache keys always unique." }, { "judge_key": "minimax_m25", "judge_name": "MiniMax M2.5", "respondent_key": "mimo_v2_flash", "respondent_name": "MiMo-V2-Flash", "weighted_score": 8, "brief_justification": "Correctly identifies the lru_cache + self reference as the primary leak source with accurate explanation. Clear structure and good code examples. Slightly misses the _instances class variable accumulation issue and the implications of the fix (API change, cache key explosion with different callback combinations)." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gpt_5_4", "respondent_name": "GPT-5.4", "weighted_score": 9.35, "brief_justification": "Accurate identification of both leaks, clear explanations, and actionable fixes with multiple design options." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "claude_opus_46", "respondent_name": "Claude Opus 4.6", "weighted_score": 9.2, "brief_justification": "Accurate identification of all leaks, thorough explanation, clear structure, insightful analysis, and practical fix provided." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gemini_31_pro", "respondent_name": "Gemini 3.1 Pro", "weighted_score": 8.4, "brief_justification": "Correctly identified the primary leak in _instances and started explaining the secondary lru_cache issue. The response is accurate and clear." }, { "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": "Excellent analysis identifying three distinct leaks with precise explanations. The fix is comprehensive and well-justified, though it misses the thread-safety aspect of the per-instance cache creation." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "grok_420", "respondent_name": "Grok 4.20", "weighted_score": 9.8, "brief_justification": "Identifies the primary leak (class-level list) and the secondary issue (lru_cache on instance method), provides multiple fixes, and explains the underlying mechanism clearly." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "deepseek_v4", "respondent_name": "DeepSeek V4", "weighted_score": 8.6, "brief_justification": "Accurate identification of primary and secondary issues, clear fixes, and practical improvements." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gpt_oss_120b", "respondent_name": "GPT-OSS-120B", "weighted_score": 9.35, "brief_justification": "Accurate identification of two leaks, thorough fixes with multiple options, clear structure and actionable code." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "gemini_3_flash", "respondent_name": "Gemini 3 Flash Preview", "weighted_score": 8.8, "brief_justification": "Accurate identification of two leaks, clear explanation, and a practical fix with good depth." }, { "judge_key": "mimo_v2_flash", "judge_name": "MiMo-V2-Flash", "respondent_key": "minimax_m25", "respondent_name": "MiniMax M2.5", "weighted_score": 8.55, "brief_justification": "Accurately identifies two leaks and provides clear fixes, but the fix for the lru_cache is incomplete as it remains per-instance." } ], "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)" } }