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vLLM/vllm/model_executor/models/transformers_pooling.py
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2025-10-15 12:11:48 +00:00

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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
# Copyright 2024 The vLLM team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Wrapper around `transformers` models for pooling tasks."""
import torch
from transformers import AutoModelForSequenceClassification
from vllm.attention import Attention, AttentionType
from vllm.compilation.decorators import support_torch_compile
from vllm.config import VllmConfig
from vllm.model_executor.layers.pooler import (
ClassifierPooler,
CLSPool,
DispatchPooler,
Pooler,
)
from vllm.sequence import IntermediateTensors
from .interfaces_base import VllmModelForPooling
from .transformers import TransformersBase, can_enable_torch_compile
from .transformers_moe import TransformersMoEBase
from .utils import WeightsMapper
class TransformersPoolingBase(TransformersBase, VllmModelForPooling):
hf_to_vllm_mapper = WeightsMapper(
# These are applied in order, so the order matters!
orig_to_new_prefix={
# Handle BERT-like models
"roberta": "model",
"bert": "model",
# Add `model.` prefix for base model checkpoints
"": "model.",
# Remove `model.` prefix if it was already there
"model.model.": "model.",
# Classifier/scoring heads will be adjacent to `model`
"model.score": "classifier",
"model.classifier": "classifier",
},
orig_to_new_suffix={
# Replace legacy suffixes used for norms
".gamma": ".weight",
".beta": ".bias",
},
)
def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
super().__init__(vllm_config=vllm_config, prefix=prefix)
# Skip unsupported/unwanted output embeddings layers
self.skip_prefixes.extend(
[
"model.lm_head.",
"model.predictions.",
"model.qa_outputs.",
"model.embeddings_project.",
"model.discriminator_predictions.",
]
)
# Some encoder models have the position_ids buffer in the checkpoint.
# vLLM will always pass position_ids as an argument, so we skip loading
# the buffer if it exists
self.skip_substrs.append("position_ids")
# Some encoder models have the bias of the final classifier layer
# in the checkpoint. vLLM does not use this bias, so we skip loading
# it if it exists
self.skip_substrs.append("score.bias")
# roberta-like models an extra padding in positions.
# FIXME(Isotr0py): This is quite hacky for roberta edge case,
# we should find a better way to handle this.
self.is_roberta = "roberta" in self.text_config.model_type
self.padding_idx = self.text_config.pad_token_id
def create_attention_instances(
self, attn_type: AttentionType = AttentionType.DECODER
) -> dict[int, Attention]:
# TODO(hmellor): Better way to detect encoder models
# In encoder models, the attention layers will have `is_causal=False`
is_encoder = lambda m: not getattr(m, "is_causal", True)
# vLLM does not support encoder-decoder models, so if any encoder layer
# is found, we assume the whole model is an encoder model
if any(is_encoder(m) for m in self.model.modules()):
attn_type = AttentionType.ENCODER_ONLY
# Check minimum transformers version for encoder models support
if attn_type == AttentionType.ENCODER_ONLY:
self.check_version("4.57.0.dev0", "encoder models support")
return super().create_attention_instances(attn_type)
def forward(
self,
input_ids: torch.Tensor | None,
positions: torch.Tensor,
intermediate_tensors: IntermediateTensors | None = None,
inputs_embeds: torch.Tensor | None = None,
) -> torch.Tensor | IntermediateTensors:
if self.is_roberta:
# RoBERTa-specific positions padding
positions += self.padding_idx + 1
return super().forward(
input_ids=input_ids,
positions=positions,
intermediate_tensors=intermediate_tensors,
inputs_embeds=inputs_embeds,
)
@support_torch_compile(enable_if=can_enable_torch_compile)
class TransformersEmbeddingModel(TransformersPoolingBase):
default_pooling_type = "CLS"
def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
super().__init__(vllm_config=vllm_config, prefix=prefix)
pooler_config = vllm_config.model_config.pooler_config
assert pooler_config is not None
self.pooler = DispatchPooler(
{
"token_embed": Pooler.for_token_embed(pooler_config),
"embed": Pooler.for_embed(pooler_config),
}
)
@support_torch_compile(enable_if=can_enable_torch_compile)
class TransformersForSequenceClassification(TransformersPoolingBase):
default_pooling_type = "CLS"
def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
super().__init__(vllm_config=vllm_config, prefix=prefix)
pooler_config = vllm_config.model_config.pooler_config
assert pooler_config is not None
# Certain information about the the model and classifier can only be
# inferred from the `ForSequenceClassification` class. Therefore, we
# instantiate it on the "meta" device to avoid allocating GPU memory.
with torch.device("meta"):
seq_cls_model = AutoModelForSequenceClassification.from_config(
self.config,
dtype=self.model_config.dtype,
trust_remote_code=self.model_config.trust_remote_code,
)
# When used for sequence classification, some models have their
# pooling layers removed. Make sure this is reflected in vLLM.
for module in seq_cls_model.modules():
if hasattr(module, "pooler") and module.pooler is None:
self.model.pooler = None
break
if self.model.pooler is not None:
raise ValueError(
"Sequence classification models with pooling layers are not "
"supported yet in the Transformers backend."
)
# Unlike `lm_head`, `classifier` is not always `nn.Linear`.
self.classifier = seq_cls_model.classifier
self.init_parameters(self.classifier, dtype=self.model_config.head_dtype)
class ClassifierWithReshape(self.classifier.__class__):
"""CLSPool has already been applied in `pooling`.
Add dim to match expected input shape of `classifier.forward`."""
def forward(self, *args, **kwargs):
if len(args) > 0:
args = (args[0].unsqueeze(1), *args[1:])
return super().forward(*args, **kwargs)
self.classifier.__class__ = ClassifierWithReshape
self.pooler = DispatchPooler(
{
"token_classify": Pooler.for_token_classify(
pooler_config, classifier=self.classifier
),
"classify": ClassifierPooler(
pooling=CLSPool(), classifier=self.classifier, act_fn="classify"
),
"score": ClassifierPooler(
pooling=CLSPool(), classifier=self.classifier, act_fn="score"
),
}
)
@support_torch_compile(enable_if=can_enable_torch_compile)
class TransformersMoEEmbeddingModel(TransformersMoEBase, TransformersEmbeddingModel):
pass
@support_torch_compile(enable_if=can_enable_torch_compile)
class TransformersMoEForSequenceClassification(
TransformersMoEBase, TransformersForSequenceClassification
):
pass