{
  "id": "huggingface/decoder-only-padding-side-warning",
  "signature": "UserWarning: You are using a decoder-only model with padding_side='right'. This may produce incorrect results. Consider setting padding_side='left' before tokenizing.",
  "signature_zh": "用户警告：你正在使用一个仅解码器模型，且 padding_side='right'。这可能会产生错误结果。建议在分词前设置 padding_side='left'。",
  "regex": "UserWarning: You are using a decoder-only model with padding_side='right'\\. This may produce incorrect results\\.",
  "domain": "huggingface",
  "category": "config_error",
  "subcategory": null,
  "root_cause": "Decoder-only models (e.g., GPT, LLaMA) expect padding on the left side to maintain causal masking; right padding causes attention to attend to padding tokens in the middle of the sequence.",
  "root_cause_type": "generic",
  "root_cause_zh": "仅解码器模型（如 GPT、LLaMA）期望在左侧进行填充以保持因果掩码；右侧填充会导致注意力机制在序列中间关注填充标记。",
  "versions": [
    {
      "version": "transformers>=4.30.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "torch>=2.0.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Python>=3.8",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "Setting padding_side='right' and adding an attention_mask is a common wrong fix; the model still sees padding in the middle of the sequence, breaking causal masking.",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Disabling padding entirely (padding=False) often causes batch processing to fail due to uneven sequence lengths, leading to a different error.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Set padding_side='left' and pad_token to eos_token before tokenizing:\nfrom transformers import AutoTokenizer\ntokenizer = AutoTokenizer.from_pretrained('meta-llama/Llama-2-7b-chat-hf')\ntokenizer.padding_side = 'left'\ntokenizer.pad_token = tokenizer.eos_token\ninputs = tokenizer(texts, padding=True, return_tensors='pt')",
      "success_rate": 0.92,
      "how": "Set padding_side='left' and pad_token to eos_token before tokenizing:\nfrom transformers import AutoTokenizer\ntokenizer = AutoTokenizer.from_pretrained('meta-llama/Llama-2-7b-chat-hf')\ntokenizer.padding_side = 'left'\ntokenizer.pad_token = tokenizer.eos_token\ninputs = tokenizer(texts, padding=True, return_tensors='pt')",
      "condition": "",
      "sources": []
    },
    {
      "action": "Use a data collator that handles left padding automatically, such as DataCollatorForSeq2Seq with padding_side='left':\nfrom transformers import DataCollatorForSeq2Seq\ndata_collator = DataCollatorForSeq2Seq(tokenizer, padding=True, pad_to_multiple_of=8)\ntokenizer.padding_side = 'left'",
      "success_rate": 0.85,
      "how": "Use a data collator that handles left padding automatically, such as DataCollatorForSeq2Seq with padding_side='left':\nfrom transformers import DataCollatorForSeq2Seq\ndata_collator = DataCollatorForSeq2Seq(tokenizer, padding=True, pad_to_multiple_of=8)\ntokenizer.padding_side = 'left'",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Set padding_side='left' and pad_token to eos_token before tokenizing:\nfrom transformers import AutoTokenizer\ntokenizer = AutoTokenizer.from_pretrained('meta-llama/Llama-2-7b-chat-hf')\ntokenizer.padding_side = 'left'\ntokenizer.pad_token = tokenizer.eos_token\ninputs = tokenizer(texts, padding=True, return_tensors='pt')",
    "Use a data collator that handles left padding automatically, such as DataCollatorForSeq2Seq with padding_side='left':\nfrom transformers import DataCollatorForSeq2Seq\ndata_collator = DataCollatorForSeq2Seq(tokenizer, padding=True, pad_to_multiple_of=8)\ntokenizer.padding_side = 'left'"
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://huggingface.co/docs/transformers/en/pad_truncation#padding-and-truncation-for-decoder-only-models",
  "official_doc_section": null,
  "error_code": null,
  "verification_tier": "ai_generated",
  "confidence": 0.88,
  "fix_success_rate": 0.92,
  "resolvable": "true",
  "first_seen": "2023-06-15",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}