feat: 重排
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@ -9,6 +9,7 @@ from transformers import AutoTokenizer, AutoModelForSequenceClassification
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import os
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import time
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import torch
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import json
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class AsyncRAGService:
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@ -38,14 +39,17 @@ class AsyncRAGService:
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),
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)
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self.tokenizer = AutoTokenizer.from_pretrained(
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"/Volumes/LRW/Model/Qwen3-Embedding-0.6B", trust_remote_code=True
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)
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self.rerank_model = AutoModelForSequenceClassification.from_pretrained(
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"/Volumes/LRW/Model/Qwen3-Embedding-0.6B",
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trust_remote_code=True,
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device_map="auto", # 或 "cuda"
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)
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self.tokenizer = AutoTokenizer.from_pretrained("/Volumes/LRW/Model/Qwen3-Embedding-0.6B", padding_side="left")
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# 强制设置 padding token
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if self.tokenizer.pad_token is None:
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self.tokenizer.pad_token = self.tokenizer.eos_token
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self.tokenizer.pad_token_id = self.tokenizer.eos_token_id
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self.rerank_model = AutoModelForSequenceClassification.from_pretrained("/Volumes/LRW/Model/Qwen3-Embedding-0.6B").eval()
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# 确保模型配置与 tokenizer 一致
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if hasattr(self.rerank_model.config, "pad_token_id"):
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self.rerank_model.config.pad_token_id = self.tokenizer.pad_token_id
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self.logger.info("RAG服务初始化完成")
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@ -214,37 +218,106 @@ class AsyncRAGService:
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return await asyncio.to_thread(_format_sources)
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async def _rerank_results(
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self, question: str, search_results: List[Dict[str, Any]]
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self, question: str, search_results: List[Dict[str, Any]], skip_rerank: bool = True
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) -> List[Dict[str, Any]]:
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"""使用 Qwen3-Reranker 对搜索结果批量重排序"""
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# 准备 batch 输入:格式必须是 Query: xxx\nDocument: yyy
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batch_texts = [
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f"Query: {question}\nDocument: {r['content'][:1000]}" # 可以根据显存调整截断长度
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if skip_rerank:
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self.logger.info("跳过重排序")
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return search_results
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if not search_results:
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return []
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# 模型相关常量(可初始化时提前保存)
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instruction = (
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"Given a web search query, retrieve relevant passages that answer the query"
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)
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prefix = '<|im_start|>system\nJudge whether the Document meets the requirements based on the Query and the Instruct provided. Note that the answer can only be "yes" or "no".<|im_end|>\n<|im_start|>user\n'
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suffix = "<|im_end|>\n<|im_start|>assistant\n<think>\n\n</think>\n\n"
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prefix_tokens = self.tokenizer.encode(prefix, add_special_tokens=False)
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suffix_tokens = self.tokenizer.encode(suffix, add_special_tokens=False)
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# 构造符合格式的输入
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def format_pair(query, doc):
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return f"<Instruct>: {instruction}\n<Query>: {query}\n<Document>: {doc}"
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pairs = [
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format_pair(question, r["content"][:1000]) # 文本截断,避免超长
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for r in search_results
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]
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# 使用 tokenizer 构建 batch 输入
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# 分词 + 拼接前后缀 + padding
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inputs = self.tokenizer(
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batch_texts,
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pairs,
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padding="max_length",
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truncation="longest_first",
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return_attention_mask=True, # 确保返回 attention_mask
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max_length=8192 - len(prefix_tokens) - len(suffix_tokens),
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return_tensors="pt",
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padding=True,
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truncation=True,
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max_length=1024, # Qwen3 的最大上下文长度,建议限制
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).to(self.rerank_model.device)
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)
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# 推理打分(关闭梯度计算)
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# 手动添加前后缀
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batch_size = inputs["input_ids"].shape[0]
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max_len = 8192
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# 创建新的输入张量
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new_input_ids = torch.full((batch_size, max_len), self.tokenizer.pad_token_id, dtype=torch.long)
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new_attention_mask = torch.zeros((batch_size, max_len), dtype=torch.long)
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for i in range(batch_size):
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# 获取原始序列(去除padding)
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original_ids = inputs["input_ids"][i]
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original_mask = inputs["attention_mask"][i]
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actual_length = original_mask.sum().item()
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# 构建新序列:prefix + original + suffix
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new_sequence = (
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prefix_tokens + original_ids[:actual_length].tolist() + suffix_tokens
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)
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new_length = len(new_sequence)
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if new_length <= max_len:
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new_input_ids[i, :new_length] = torch.tensor(new_sequence)
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new_attention_mask[i, :new_length] = 1
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inputs = {
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"input_ids": new_input_ids.to(self.rerank_model.device),
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"attention_mask": new_attention_mask.to(self.rerank_model.device),
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}
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# 获取 yes / no 的 token id(初始化时保存也可)
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token_true_id = self.tokenizer.convert_tokens_to_ids("yes")
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token_false_id = self.tokenizer.convert_tokens_to_ids("no")
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# 推理评分
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with torch.no_grad():
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outputs = self.rerank_model(**inputs)
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logits = outputs.logits.squeeze(-1)
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logits = outputs.logits
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# 如果是二分类模型,通常需要做 sigmoid 激活
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scores = torch.sigmoid(logits).tolist()
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# 检查 logits 的维度
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if logits.dim() == 3:
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# 如果是3维,取最后一个token的logits
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logits = logits[:, -1, :]
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elif logits.dim() == 2:
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# 如果是2维,直接使用
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pass
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else:
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raise ValueError(f"Unexpected logits dimension: {logits.dim()}")
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# 写入到每个 search_result 中
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# 提取 yes/no token 的 logits
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true_logits = logits[:, token_true_id]
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false_logits = logits[:, token_false_id]
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stacked = torch.stack([false_logits, true_logits], dim=1)
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probs = torch.nn.functional.softmax(stacked, dim=1)
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scores = probs[:, 1].tolist() # 取 "yes" 的概率值
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# 写入每条结果
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for r, score in zip(search_results, scores):
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r["rerank_score"] = max(0.0, min(score, 1.0)) # 保证分数在 0-1 范围
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r["rerank_score"] = round(float(score), 4)
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self.logger.info(f"重排序完成,得分范围: {min(scores)} - {max(scores)} \n\n {json.dumps(search_results, indent=4)}")
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return search_results
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async def _build_context_async(self, search_results: List[Dict[str, Any]]) -> str:
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