Add reasoning parser mechanism + qwen3 parser + bugfixes

This commit is contained in:
2026-06-10 18:22:29 +08:00
parent 4ab36b51d5
commit 365da18436
9 changed files with 3821 additions and 0 deletions

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"""
Reasoning parser module for vLLM 0.6.3 (BI-V100 / Qwen3.6-27B adaptation).
Usage: --reasoning-parser qwen3
"""
from vllm.reasoning.abs_reasoning_parsers import ReasoningParser, ReasoningParserManager
__all__ = ["ReasoningParser", "ReasoningParserManager"]
# Lazy-register Qwen3 parser; imported on first get_reasoning_parser("qwen3").
ReasoningParserManager.register_lazy(
"qwen3",
"vllm.reasoning.qwen3_reasoning_parser",
"Qwen3ReasoningParser",
)

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"""
Abstract reasoning parser base classes for vLLM 0.6.3.
Adapted from vllm-original/vllm/reasoning/abs_reasoning_parsers.py:
- Removed vllm.entrypoints.mcp, vllm.utils.collection_utils, import_utils
- DeltaMessage from vllm 0.6.3 protocol path
- TokenizerLike -> AnyTokenizer
- ReasoningParserManager: simplified eager + lazy registration
"""
import importlib
from abc import abstractmethod
from collections.abc import Iterable, Sequence
from functools import cached_property
from typing import Any, Optional, TYPE_CHECKING
if TYPE_CHECKING:
from vllm.entrypoints.openai.protocol import DeltaMessage
from vllm.transformers_utils.tokenizer import AnyTokenizer
else:
DeltaMessage = Any
AnyTokenizer = Any
class ReasoningParser:
"""Abstract base for all reasoning parsers."""
def __init__(self, tokenizer: "AnyTokenizer", *args, **kwargs):
self.model_tokenizer = tokenizer
@cached_property
def vocab(self) -> dict:
return self.model_tokenizer.get_vocab()
@abstractmethod
def is_reasoning_end(self, input_ids: Sequence[int]) -> bool:
"""Return True once the reasoning block has closed in input_ids."""
def is_reasoning_end_streaming(
self, input_ids: Sequence[int], delta_ids: Iterable[int]
) -> bool:
return self.is_reasoning_end(input_ids)
@abstractmethod
def extract_content_ids(self, input_ids: list) -> list:
"""Return token ids that belong to the content (post-reasoning) part."""
def count_reasoning_tokens(self, token_ids: Sequence[int]) -> int:
return 0
@abstractmethod
def extract_reasoning(
self, model_output: str, request: Any
) -> "tuple[Optional[str], Optional[str]]":
"""
Split a complete model output into (reasoning_text, content_text).
Either part may be None.
"""
@abstractmethod
def extract_reasoning_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
) -> Optional["DeltaMessage"]:
"""
Extract reasoning from a streaming delta.
Returns a DeltaMessage with reasoning_content and/or content set,
or None if this delta should be suppressed (control token).
"""
class BaseThinkingReasoningParser(ReasoningParser):
"""
Base for parsers that use <start_token>...</end_token> delimiters.
Subclasses define start_token / end_token properties.
"""
@property
@abstractmethod
def start_token(self) -> str:
raise NotImplementedError
@property
@abstractmethod
def end_token(self) -> str:
raise NotImplementedError
def __init__(self, tokenizer: "AnyTokenizer", *args, **kwargs):
super().__init__(tokenizer, *args, **kwargs)
if not self.model_tokenizer:
raise ValueError("Tokenizer must be passed to ReasoningParser.")
if not self.start_token or not self.end_token:
raise ValueError("start_token and end_token must be defined.")
self.start_token_id: Optional[int] = self.vocab.get(self.start_token)
self.end_token_id: Optional[int] = self.vocab.get(self.end_token)
if self.start_token_id is None or self.end_token_id is None:
raise RuntimeError(
f"{self.__class__.__name__}: could not find think tokens "
f"'{self.start_token}'/'{self.end_token}' in tokenizer vocab."
)
def is_reasoning_end(self, input_ids: Sequence[int]) -> bool:
for token_id in reversed(input_ids):
if token_id == self.start_token_id:
return False
if token_id == self.end_token_id:
return True
return False
def is_reasoning_end_streaming(
self, input_ids: Sequence[int], delta_ids: Iterable[int]
) -> bool:
return self.end_token_id in delta_ids
def extract_content_ids(self, input_ids: list) -> list:
if self.end_token_id not in input_ids[:-1]:
return []
return input_ids[input_ids.index(self.end_token_id) + 1:]
def count_reasoning_tokens(self, token_ids: Sequence[int]) -> int:
count = 0
depth = 0
for tid in token_ids:
if tid == self.start_token_id:
depth += 1
elif tid == self.end_token_id:
if depth > 0:
depth -= 1
elif depth > 0:
count += 1
return count
def extract_reasoning(
self, model_output: str, request: Any
) -> "tuple[Optional[str], Optional[str]]":
# Strip <think> if the model generated it (old-style template).
parts = model_output.partition(self.start_token)
model_output = parts[2] if parts[1] else parts[0]
if self.end_token not in model_output:
return model_output, None
reasoning, _, content = model_output.partition(self.end_token)
return reasoning, content or None
def extract_reasoning_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
) -> Optional["DeltaMessage"]:
from vllm.entrypoints.openai.protocol import DeltaMessage as _DeltaMessage
# Suppress lone control tokens.
if len(delta_token_ids) == 1 and delta_token_ids[0] in (
self.start_token_id, self.end_token_id
):
return None
start_in_prev = self.start_token_id in previous_token_ids
start_in_delta = self.start_token_id in delta_token_ids
end_in_prev = self.end_token_id in previous_token_ids
end_in_delta = self.end_token_id in delta_token_ids
if start_in_prev:
if end_in_delta:
end_idx = delta_text.find(self.end_token)
reasoning = delta_text[:end_idx] if end_idx >= 0 else ""
content = delta_text[end_idx + len(self.end_token):] if end_idx >= 0 else None
return _DeltaMessage(
reasoning_content=reasoning or None,
content=content or None,
)
elif end_in_prev:
return _DeltaMessage(content=delta_text)
else:
return _DeltaMessage(reasoning_content=delta_text)
elif start_in_delta:
if end_in_delta:
start_idx = delta_text.find(self.start_token)
end_idx = delta_text.find(self.end_token)
reasoning = delta_text[start_idx + len(self.start_token):end_idx]
content = delta_text[end_idx + len(self.end_token):]
return _DeltaMessage(
reasoning_content=reasoning or None,
content=content or None,
)
else:
return _DeltaMessage(reasoning_content=delta_text)
else:
return _DeltaMessage(content=delta_text)
class ReasoningParserManager:
"""
Registry for ReasoningParser implementations.
Supports eager and lazy registration.
"""
_parsers: dict = {} # name -> class (eager)
_lazy: dict = {} # name -> (module_path, class_name)
@classmethod
def register_module(cls, name: str, parser_cls: type) -> None:
"""Eagerly register a ReasoningParser class."""
if not issubclass(parser_cls, ReasoningParser):
raise TypeError(f"{parser_cls} is not a ReasoningParser subclass.")
cls._parsers[name] = parser_cls
@classmethod
def register_lazy(cls, name: str, module_path: str, class_name: str) -> None:
"""Register a parser for deferred import."""
cls._lazy[name] = (module_path, class_name)
@classmethod
def get_reasoning_parser(cls, name: str) -> type:
if name in cls._parsers:
return cls._parsers[name]
if name in cls._lazy:
module_path, class_name = cls._lazy[name]
mod = importlib.import_module(module_path)
parser_cls = getattr(mod, class_name)
cls._parsers[name] = parser_cls
return parser_cls
registered = sorted(set(cls._parsers) | set(cls._lazy))
raise KeyError(
f"Reasoning parser '{name}' not found. "
f"Available: {registered}"
)
@classmethod
def list_registered(cls) -> list:
return sorted(set(cls._parsers) | set(cls._lazy))

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"""
Reasoning parser for Qwen3 / Qwen3.5 / Qwen3.6 model family.
Adapted from vllm-original/vllm/reasoning/qwen3_reasoning_parser.py.
The model uses <think>...</think> to wrap chain-of-thought output.
For Qwen3.5+ the chat template injects <think> into the prompt, so only
</think> appears in the generated tokens; older templates generate <think>
themselves. Both styles are handled.
"""
from typing import Optional, Sequence, Any
from vllm.reasoning.abs_reasoning_parsers import (
BaseThinkingReasoningParser,
ReasoningParserManager,
)
class Qwen3ReasoningParser(BaseThinkingReasoningParser):
def __init__(self, tokenizer: Any, *args, **kwargs):
super().__init__(tokenizer, *args, **kwargs)
chat_kwargs = kwargs.get("chat_template_kwargs", {}) or {}
self.thinking_enabled = chat_kwargs.get("enable_thinking", True)
@property
def start_token(self) -> str:
return "<think>"
@property
def end_token(self) -> str:
return "</think>"
def extract_reasoning(
self, model_output: str, request: Any
) -> "tuple[Optional[str], Optional[str]]":
# Strip <think> if the model generated it (old template / edge case).
parts = model_output.partition(self.start_token)
model_output = parts[2] if parts[1] else parts[0]
if self.end_token not in model_output:
if not self.thinking_enabled:
return None, model_output
# Thinking enabled but output truncated before </think>.
return model_output, None
reasoning, _, content = model_output.partition(self.end_token)
return reasoning, content or None
def count_reasoning_tokens(self, token_ids: Sequence[int]) -> int:
token_ids = list(token_ids)
if self.start_token_id in token_ids:
# Old-style template: model generates <think> itself.
# Use depth-counting from the base class.
return super().count_reasoning_tokens(token_ids)
elif self.end_token_id in token_ids:
# New-style template (Qwen3.5+): <think> is injected into the
# prompt, so output starts already inside the thinking block.
# Every token before </think> is a reasoning token.
return token_ids.index(self.end_token_id)
else:
# No </think> in output: either truncated (all reasoning)
# or thinking disabled (none).
return len(token_ids) if self.thinking_enabled else 0
def extract_reasoning_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
):
from vllm.entrypoints.openai.protocol import DeltaMessage
if not self.thinking_enabled:
return DeltaMessage(content=delta_text) if delta_text else None
# Strip <think> from delta if the model generates it itself.
if self.start_token_id in delta_token_ids:
start_idx = delta_text.find(self.start_token)
if start_idx >= 0:
delta_text = delta_text[start_idx + len(self.start_token):]
if self.end_token_id in delta_token_ids:
end_idx = delta_text.find(self.end_token)
if end_idx >= 0:
reasoning = delta_text[:end_idx]
content = delta_text[end_idx + len(self.end_token):]
if not reasoning and not content:
return None
return DeltaMessage(
reasoning_content=reasoning or None,
content=content or None,
)
return None
if not delta_text:
return None
elif self.end_token_id in previous_token_ids:
return DeltaMessage(content=delta_text)
else:
return DeltaMessage(reasoning_content=delta_text)
# Register immediately when this module is imported.
ReasoningParserManager.register_module("qwen3", Qwen3ReasoningParser)