Files
vllm/vllm/v1/engine/__init__.py
afeldman-nm 0630d4537a [V1] Logprobs and prompt logprobs support (#9880)
This PR is adding support for sample logprobs & prompt logprobs to vLLM v1.

New behavior:

- During model execution, model runner computes sample logprobs (if user-provided logprobs setting is not None) and prompt logprobs (if user-provided prompt_logprobs setting is not None). For both sample and prompt logprobs, the engine core returns 3 vectors: token ids, token logprob values, token ranks. Ranks reflect tokens' 1-indexed positions in the vocabulary vector after sorting the vocabulary by log probability in descending order.
- In scheduler.update_from_output(), sample and prompt logprobs are incorporated into the EngineCoreOutput data structure which is transferred to the engine client. If multiprocessing is enabled, then sample and prompt logprobs will be (de)serialized when the EngineCoreOutput data structure is (de)serialized.
- During output processing, the LogprobsProcessor transforms the triplet of token ids, token logprobs values, and token ranks into the OpenAI-compatible List[Dict[token id,Logprob]] format (for sample and prompt logprobs respectively.)
- Each Logprob instance (whether sample- or prompt-) consists of a token's log-probability, rank, and detokenized string representation. Note that logprob detokenization is handled by the LogprobsProcessor not the detokenizer.

Signed-off-by: Andrew Feldman <afeldman@neuralmagic.com>
Signed-off-by: Nick Hill <nhill@redhat.com>
Signed-off-by: rshaw@neuralmagic.com <rshaw@neuralmagic.com>


Co-authored-by: rshaw@neuralmagic.com <rshaw@neuralmagic.com>
Co-authored-by: Nick Hill <nhill@redhat.com>
2025-02-07 07:26:20 -08:00

120 lines
3.2 KiB
Python

# SPDX-License-Identifier: Apache-2.0
import enum
from dataclasses import dataclass
from typing import TYPE_CHECKING, List, Optional, Union
import msgspec
from vllm.v1.metrics.stats import SchedulerStats
from vllm.v1.outputs import LogprobsLists, LogprobsTensors
if TYPE_CHECKING:
from vllm.lora.request import LoRARequest
from vllm.multimodal import MultiModalKwargs
from vllm.multimodal.inputs import PlaceholderRange
from vllm.sampling_params import SamplingParams
# These are possible values of RequestOutput.finish_reason,
# so form part of the external API.
FINISH_REASON_STRINGS = ("stop", "length", "abort")
class FinishReason(enum.IntEnum):
"""
Reason a request finished - stop, length, or abort.
Int rather than Str for more compact serialization.
stop - a stop string was emitted
length - max_tokens was consumed, or max_model_len was reached
abort - aborted for another reason
"""
STOP = 0
LENGTH = 1
ABORT = 2
def __str__(self):
return FINISH_REASON_STRINGS[self.value]
@dataclass
class EngineCoreRequest:
# NOTE: prompt and prompt_token_ids should be DecoderOnlyInput,
# but this object is currently not playing well with msgspec
# due to circular imports and typing we have in data.py
request_id: str
# NOTE(ywang96): original text prompt is needed when a request is added to
# Detokenizer, but set to None when it is added to EngineCoreClient.
prompt: Optional[str]
prompt_token_ids: List[int]
mm_inputs: Optional[List[Optional["MultiModalKwargs"]]]
mm_hashes: Optional[List[str]]
mm_placeholders: Optional[List["PlaceholderRange"]]
sampling_params: "SamplingParams"
eos_token_id: Optional[int]
arrival_time: float
lora_request: Optional["LoRARequest"]
class EngineCoreOutput(
msgspec.Struct,
array_like=True, # type: ignore[call-arg]
omit_defaults=True, # type: ignore[call-arg]
gc=False): # type: ignore[call-arg]
request_id: str
new_token_ids: List[int]
new_logprobs: Optional[LogprobsLists] = None
new_prompt_logprobs_tensors: Optional[LogprobsTensors] = None
finish_reason: Optional[FinishReason] = None
stop_reason: Union[int, str, None] = None
@property
def finished(self) -> bool:
return self.finish_reason is not None
class EngineCoreOutputs(
msgspec.Struct,
array_like=True, # type: ignore[call-arg]
omit_defaults=True, # type: ignore[call-arg]
gc=False): # type: ignore[call-arg]
#NOTE(Nick): We could consider ways to make this more compact,
# e.g. columnwise layout
# [num_reqs]
outputs: List[EngineCoreOutput]
scheduler_stats: SchedulerStats
@dataclass
class EngineCoreProfile:
is_start: bool
@dataclass
class EngineCoreResetPrefixCache:
pass
class EngineCoreRequestType(enum.Enum):
"""
Request types defined as hex byte strings, so it can be sent over sockets
without separate encoding step.
"""
ADD = b'\x00'
ABORT = b'\x01'
PROFILE = b'\x02'
RESET_PREFIX_CACHE = b'\x03'
EngineCoreRequestUnion = Union[EngineCoreRequest, EngineCoreProfile,
EngineCoreResetPrefixCache, List[str]]