[V0 Deprecation] Remove V0 Output Processor (#25320)

Signed-off-by: Woosuk Kwon <woosuk@thinkingmachines.ai>
Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>
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Woosuk Kwon 2025-09-20 17:57:20 -07:00 committed by GitHub
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commit 86647d1cd0
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6 changed files with 40 additions and 384 deletions

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@ -1,39 +0,0 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import Cython.Compiler.Options
from Cython.Build import cythonize
from setuptools import setup
Cython.Compiler.Options.annotate = True
infiles = []
infiles += [
"vllm/engine/llm_engine.py",
"vllm/transformers_utils/detokenizer.py",
"vllm/engine/output_processor/single_step.py",
"vllm/outputs.py",
"vllm/engine/output_processor/stop_checker.py",
]
infiles += [
"vllm/core/scheduler.py",
"vllm/sequence.py",
"vllm/core/block_manager.py",
]
infiles += [
"vllm/model_executor/layers/sampler.py",
"vllm/sampling_params.py",
"vllm/utils/__init__.py",
]
setup(ext_modules=cythonize(infiles,
annotate=False,
force=True,
compiler_directives={
'language_level': "3",
'infer_types': True
}))
# example usage: python3 build_cython.py build_ext --inplace

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@ -1,59 +0,0 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from abc import ABC, abstractmethod
from typing import List
from vllm.config import SchedulerConfig
from vllm.core.scheduler import Scheduler
from vllm.engine.output_processor.stop_checker import StopChecker
from vllm.sequence import SequenceGroup, SequenceGroupOutput
from vllm.transformers_utils.detokenizer import Detokenizer
from vllm.utils import Counter
class SequenceGroupOutputProcessor(ABC):
"""Interface for logic that processes new token ids in sequence groups,
managing detokenization, stop checking, and freeing/forking sequences with
the scheduler.
This is highly coupled with the LLMEngine and should be seen as an extension
of it. The logic is separated to simplify the LLMEngine class and allow
separate implementations for single-step decoding (which supports beam
search sequence forking) and multi-step decoding (which does not support
beam search, but does support speculative decoding).
"""
@staticmethod
def create_output_processor(
scheduler_config: SchedulerConfig,
detokenizer: Detokenizer,
scheduler: List[Scheduler],
seq_counter: Counter,
stop_checker: "StopChecker",
):
"""Create an output processor.
Multi-step scheduling is no longer supported. Always return a
single-step output processor.
"""
from vllm.engine.output_processor.single_step import (
SingleStepOutputProcessor)
return SingleStepOutputProcessor(scheduler_config, detokenizer,
scheduler, seq_counter, stop_checker)
@abstractmethod
def process_outputs(self, sequence_group: SequenceGroup,
outputs: List[SequenceGroupOutput],
is_async: bool) -> None:
"""Process new token ids for the sequence group. Handles logic such as
detokenization, stop checking, and freeing/forking sequences in the
scheduler.
"""
pass
@abstractmethod
def process_prompt_logprob(self, seq_group: SequenceGroup,
outputs: List[SequenceGroupOutput]) -> None:
"""Update prompt logprobs received from outputs to seq_group."""
pass

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@ -1,145 +0,0 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from typing import List
from vllm.config import SchedulerConfig
from vllm.core.scheduler import Scheduler
from vllm.engine.output_processor.interfaces import (
SequenceGroupOutputProcessor)
from vllm.engine.output_processor.stop_checker import StopChecker
from vllm.logger import init_logger
from vllm.sequence import (CompletionSequenceGroupOutput, SequenceGroup,
SequenceGroupOutput)
from vllm.transformers_utils.detokenizer import Detokenizer
from vllm.utils import Counter
logger = init_logger(__name__)
def single_step_process_prompt_logprob(
sg_output_proc: SequenceGroupOutputProcessor, seq_group: SequenceGroup,
output: CompletionSequenceGroupOutput) -> None:
"""Process prompt logprobs associated with the
[`SequenceGroupOutput`][vllm.sequence.SequenceGroupOutput] for a given step.
Do nothing if the output has no prompt logprobs.
Account for the fact that transformers do not compute first-token logprobs.
Args:
sg_output_proc:
[`SequenceGroupOutputProcessor`][vllm.engine.output_processor.interfaces.SequenceGroupOutputProcessor]
instance
seq_group: the output is associated with this
[`SequenceGroup`][vllm.sequence.SequenceGroup]
output: the [`SequenceGroupOutput`][vllm.sequence.SequenceGroupOutput]
for a single scheduler step
"""
prompt_logprobs = output.prompt_logprobs
# If this is the first (or only) "chunk" of the prefill, we need
# to prepend None to the list of prompt logprobs. The reason for this
# is that for N prompt tokens, the Sampler will generate N-1 total
# prompt logprobs during prefill since the token at idx 0 will not
# have a logprob associated with it.
if prompt_logprobs is not None:
if not seq_group.prompt_logprobs:
prompt_logprobs = [None] + prompt_logprobs
seq_group.prompt_logprobs = []
assert hasattr(sg_output_proc, 'detokenizer')
if (seq_group.sampling_params.detokenize
and sg_output_proc.detokenizer):
sg_output_proc.detokenizer.decode_prompt_logprobs_inplace(
seq_group,
prompt_logprobs,
position_offset=len(seq_group.prompt_logprobs))
seq_group.prompt_logprobs.extend(prompt_logprobs)
class SingleStepOutputProcessor(SequenceGroupOutputProcessor):
"""SequenceGroupOutputProcessor which handles "output processing" logic,
which happens after the model returns generated token ids and before
scheduling of the next batch. Output processing logic includes
detokenization, and determining if a sequence is finished (e.g. via max len
or eos token).
The SingleStepOutputProcessor is specialized to the case where the model
emits at most a single token per invocation, which precludes configurations
such as speculative decoding or multi-step decoding. This enables beam
search sampling, which requires forking/finishing/freeing sequences in a way
that is currently difficult to schedule multiple steps ahead of time.
"""
def __init__(self, scheduler_config: SchedulerConfig,
detokenizer: Detokenizer, scheduler: List[Scheduler],
seq_counter: Counter, stop_checker: StopChecker):
self.scheduler_config = scheduler_config
self.detokenizer = detokenizer
self.scheduler = scheduler
self.seq_counter = seq_counter
self.stop_checker = stop_checker
def process_outputs(self, sequence_group: SequenceGroup,
outputs: List[SequenceGroupOutput],
is_async: bool) -> None:
"""Append all new tokens to sequences in the sequence group. Fork any
surviving beam candidates; free any unsurviving ones.
Invokes detokenizer to detokenize new tokens, and also marks sequences
as finished if they meet stop conditions.
is_async - Indicates whether this postprocessor runs in
parallel with the GPU forward pass and is processing
tokens from the previous step. If this is true, then
no tokens need to be appended since it is already done
externally (before the next schedule() call)
"""
assert (len(outputs) == 1
), f"{type(self)} does not support multiple outputs per step"
return self._process_sequence_group_outputs(sequence_group, outputs[0],
is_async)
def process_prompt_logprob(self, seq_group: SequenceGroup,
outputs: List[SequenceGroupOutput]) -> None:
"""Process prompt logprobs associated with one step of a single-step-
scheduled computation.
Args:
seq_group: the output is associated with this
[`SequenceGroup`][vllm.sequence.SequenceGroup]
outputs: the
[`SequenceGroupOutput`][vllm.sequence.SequenceGroupOutput]
for a single scheduler step
"""
assert len(outputs) == 1, "Single step should only have 1 output."
output = outputs[0]
assert isinstance(output, CompletionSequenceGroupOutput)
single_step_process_prompt_logprob(self, seq_group, output)
def _process_sequence_group_outputs(self, seq_group: SequenceGroup,
outputs: SequenceGroupOutput,
is_async: bool) -> None:
sampling_params = seq_group.sampling_params
sample = outputs.samples[0]
seq = seq_group.first_seq
if not is_async:
seq.append_token_id(sample.output_token, sample.logprobs,
sample.output_embed)
if sampling_params.detokenize and self.detokenizer:
new_char_count = self.detokenizer.decode_sequence_inplace(
seq, sampling_params)
else:
new_char_count = 0
self.stop_checker.maybe_stop_sequence(
seq,
new_char_count,
sampling_params,
lora_req=seq_group.lora_request,
)
if seq.is_finished():
for scheduler in self.scheduler:
scheduler.free_seq(seq)

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@ -1,139 +0,0 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from typing import List, Optional, Tuple
from vllm.lora.request import LoRARequest
from vllm.reasoning import ReasoningParser
from vllm.sampling_params import SamplingParams
from vllm.sequence import Sequence, SequenceStatus
class StopChecker:
"""LLMEngine helper class which separates out the logic involving stop
checking. This checks things such as: whether the eos token was emitted,
whether the max_tokens has been consumed, whether a stop string has been
emitted, or if we have exceeded the max model len.
"""
def __init__(
self,
max_model_len: int,
reasoner: Optional[ReasoningParser] = None,
):
# Do not use it directly, but use `self._get_max_model_len`.
self._max_model_len = max_model_len
self.reasoner = reasoner
def _get_max_model_len(self, lora_req: Optional[LoRARequest]):
if lora_req and lora_req.long_lora_max_len:
return lora_req.long_lora_max_len
else:
return self._max_model_len
def maybe_stop_sequence(
self,
seq: Sequence,
new_char_count: int,
sampling_params: SamplingParams,
lora_req: Optional[LoRARequest] = None,
) -> None:
"""Stop the finished sequences.
new_char_count is the number of chars added to the
sequence's output text for the newly generated token
"""
# Check if the minimum number of tokens has been generated yet;
# skip the stop string/token checks if not
if seq.get_output_len() < sampling_params.min_tokens:
return
# Check if the sequence has generated the EOS token.
if ((not sampling_params.ignore_eos)
and seq.get_last_token_id() == seq.eos_token_id):
# Remove the last EOS token unless explicitly specified
# This prevents unintended exposure of the EOS token
if new_char_count and (
not sampling_params.include_stop_str_in_output):
seq.output_text = seq.output_text[:-new_char_count]
seq.status = SequenceStatus.FINISHED_STOPPED
return
# Skip stop string/token checks if in reasoning content generation
if self.reasoner is not None and \
not self.reasoner.is_reasoning_end(seq.get_token_ids()):
return
# Check if a stop token was encountered.
# This assumes a single token produced per step.
last_token_id = seq.get_last_token_id()
if last_token_id in (sampling_params.stop_token_ids or ()):
if new_char_count and (
not sampling_params.include_stop_str_in_output):
# Remove last token
seq.output_text = seq.output_text[:-new_char_count]
seq.status = SequenceStatus.FINISHED_STOPPED
seq.stop_reason = last_token_id
return
# Check if any stop strings are matched.
stop = self.check_stop_strings(
seq.output_text, new_char_count, sampling_params.stop,
sampling_params.include_stop_str_in_output)
if stop is not None:
stop_str, truncate_to = stop
if truncate_to != -1:
seq.output_text = seq.output_text[:truncate_to]
seq.status = SequenceStatus.FINISHED_STOPPED
seq.stop_reason = stop_str
return
# Check if the sequence has reached max_model_len.
if seq.get_len() >= self._get_max_model_len(lora_req):
seq.status = SequenceStatus.FINISHED_LENGTH_CAPPED
return
# Check if the sequence has reached max_tokens.
if seq.get_output_len() == sampling_params.max_tokens:
seq.status = SequenceStatus.FINISHED_LENGTH_CAPPED
return
@staticmethod
def check_stop_strings(
output_text: str,
new_char_count: int,
stop: List[str],
include_in_output: bool,
) -> Optional[Tuple[str, int]]:
"""Check if any stop strings are matched and truncate sequence
output text accordingly.
Returns tuple (stop_string, offset) if matched or else None.
Where stop_string is the matched stop string and offset is the
length to which output_text should be truncated, or -1 for no
truncation.
"""
if not new_char_count or not stop:
return None
for stop_str in stop:
stop_string_len = len(stop_str)
# Avoid searching already-searched text.
stop_index = output_text.find(stop_str,
1 - new_char_count - stop_string_len)
if stop_index == -1:
continue
if include_in_output:
# Truncate to end of stop string.
stop_index += stop_string_len
if stop_index >= len(output_text):
# No truncation required.
return stop_str, -1
# Truncate the output text to either the beginning
# or end of the stop string.
return stop_str, stop_index
return None

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@ -9,7 +9,6 @@ from tokenizers import Tokenizer
from tokenizers.decoders import DecodeStream
from transformers import PreTrainedTokenizerFast
from vllm.engine.output_processor.stop_checker import StopChecker
from vllm.logger import init_logger
from vllm.transformers_utils.detokenizer_utils import (
AnyTokenizer, convert_prompt_ids_to_tokens, detokenize_incrementally)
@ -129,7 +128,7 @@ class BaseIncrementalDetokenizer(IncrementalDetokenizer, ABC):
# 2) Evaluate stop strings.
stop_string = None
if self.stop and len(self.output_token_ids) > self.min_tokens:
stop = StopChecker.check_stop_strings(
stop = check_stop_strings(
output_text=self.output_text,
new_char_count=len(self.output_text) - stop_check_offset,
stop=self.stop,
@ -309,3 +308,42 @@ class SlowIncrementalDetokenizer(BaseIncrementalDetokenizer):
self.read_offset = read_offset
return decoded_text
def check_stop_strings(
output_text: str,
new_char_count: int,
stop: list[str],
include_in_output: bool,
) -> Optional[tuple[str, int]]:
"""Check if any stop strings are matched and truncate sequence
output text accordingly.
Returns tuple (stop_string, offset) if matched or else None.
Where stop_string is the matched stop string and offset is the
length to which output_text should be truncated, or -1 for no
truncation.
"""
if not new_char_count or not stop:
return None
for stop_str in stop:
stop_string_len = len(stop_str)
# Avoid searching already-searched text.
stop_index = output_text.find(stop_str,
1 - new_char_count - stop_string_len)
if stop_index == -1:
continue
if include_in_output:
# Truncate to end of stop string.
stop_index += stop_string_len
if stop_index >= len(output_text):
# No truncation required.
return stop_str, -1
# Truncate the output text to either the beginning
# or end of the stop string.
return stop_str, stop_index
return None