436 lines
17 KiB
Python
436 lines
17 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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# Copyright 2024 The vLLM team.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Transformers backend base class."""
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from collections.abc import Iterable
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from typing import TYPE_CHECKING
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import regex as re
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import torch
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import transformers
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from packaging.version import Version
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from torch import nn
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from transformers import AutoModel
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from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS
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from vllm.attention import Attention, AttentionType
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from vllm.config.utils import getattr_iter
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from vllm.distributed import get_pp_group, get_tp_group
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from vllm.distributed.utils import get_pp_indices
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from vllm.logger import init_logger
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from vllm.model_executor.layers.vocab_parallel_embedding import VocabParallelEmbedding
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from vllm.model_executor.models.interfaces import (
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SupportsLoRA,
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SupportsPP,
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SupportsQuant,
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)
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from vllm.model_executor.models.interfaces_base import VllmModel
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from vllm.model_executor.models.transformers.utils import (
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get_feature_request_tip,
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init_on_device_without_buffers,
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log_replacement,
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replace_linear_class,
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replace_rms_norm_class,
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)
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from vllm.model_executor.models.utils import (
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AutoWeightsLoader,
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PPMissingLayer,
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make_empty_intermediate_tensors_factory,
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maybe_prefix,
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)
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from vllm.sequence import IntermediateTensors
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if TYPE_CHECKING:
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from transformers import PreTrainedModel
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from vllm.config import VllmConfig
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else:
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PreTrainedModel = object
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logger = init_logger(__name__)
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def vllm_flash_attention_forward(
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# Transformers args
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module: torch.nn.Module,
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query: torch.Tensor,
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key: torch.Tensor,
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value: torch.Tensor,
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attention_mask: torch.Tensor,
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# Transformers kwargs
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scaling: float | None = None,
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# vLLM kwargs
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attention_instances: dict[int, Attention] | None = None,
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**kwargs,
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):
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self_attn = attention_instances[module.layer_idx]
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if scaling is not None:
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self_attn.impl.scale = float(scaling)
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hidden = query.shape[-2]
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query, key, value = (x.transpose(1, 2) for x in (query, key, value))
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query, key, value = (x.reshape(hidden, -1) for x in (query, key, value))
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return self_attn.forward(query, key, value), None
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ALL_ATTENTION_FUNCTIONS["vllm"] = vllm_flash_attention_forward
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class Base(nn.Module, VllmModel, SupportsQuant, SupportsLoRA, SupportsPP):
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embedding_padding_modules = ["lm_head"]
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embedding_modules = ["embed_tokens"] # TODO transformers will have a util to get it
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def __init__(self, *, vllm_config: "VllmConfig", prefix: str = ""):
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super().__init__()
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logger.info("Using Transformers backend.")
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self.config = vllm_config.model_config.hf_config
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self.text_config = self.config.get_text_config()
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self.cache_config = vllm_config.cache_config
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self.device_config = vllm_config.device_config
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self.model_config = vllm_config.model_config
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self.parallel_config = vllm_config.parallel_config
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self.quant_config = vllm_config.quant_config
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self.pp_group = get_pp_group()
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self.tp_group = get_tp_group()
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# Weights to skip in `self.load_weights`
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self.skip_prefixes: list[str] = []
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"""Skip loading weights whose qualname starts with these prefixes."""
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self.skip_substrs: list[str] = []
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"""Skip loading weights whose qualname contains these substrings."""
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self.ignore_unexpected_prefixes: list[str] = []
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"""Ignore unexpected weights whose qualname starts with these prefixes.
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"""
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self.ignore_unexpected_suffixes: list[str] = []
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"""Ignore unexpected weights whose qualname ends with these suffixes."""
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if self.quant_config:
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quant_method_name = self.quant_config.get_name()
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# Check for unsupported quantization methods.
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if quant_method_name == "mxfp4":
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raise NotImplementedError(
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"Transformers backend does not support MXFP4 quantization yet."
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)
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# Skip loading extra bias for GPTQ models.
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if "gptq" in quant_method_name:
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self.ignore_unexpected_suffixes.append(".bias")
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# Set correct attn and init on "meta" to delay allocating GPU tensors
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self.text_config._attn_implementation = "vllm"
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with init_on_device_without_buffers("meta"):
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self.model: PreTrainedModel = AutoModel.from_config(
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self.config,
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dtype=self.model_config.dtype,
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trust_remote_code=self.model_config.trust_remote_code,
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)
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# Remove layers not on this pipeline parallel rank
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self.pipeline_parallel()
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# Substitute remaining layers with vLLM's layers as needed
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self.recursive_replace()
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# Create attention instances for KV cache allocation
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self.attention_instances = self.create_attention_instances()
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# Input embeddings
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input_embeddings = self.model.get_input_embeddings()
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if not isinstance(input_embeddings, PPMissingLayer):
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# Some models scale embeddings inside the input embedding layer
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self.embed_scale = getattr(input_embeddings, "embed_scale", None)
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names = ("embedding_size", "hidden_size")
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embedding_dim = getattr_iter(self.text_config, names, None)
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assert embedding_dim is not None
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self.model.set_input_embeddings(
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VocabParallelEmbedding(
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self.text_config.vocab_size,
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embedding_dim=embedding_dim,
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org_num_embeddings=self.text_config.vocab_size,
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quant_config=self.quant_config,
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)
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)
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# Initialize any parameters that have not had their modules replaced
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self.init_parameters(self.model)
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# Pipeline parallel intermediate tensors
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self.make_empty_intermediate_tensors = make_empty_intermediate_tensors_factory(
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["hidden_states"], self.text_config.hidden_size
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)
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def pipeline_parallel(self):
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"""
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Apply the model's pipeline parallelization plan.
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"""
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if self.pp_group.world_size <= 1:
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return
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if not self.model.supports_pp_plan:
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tip = get_feature_request_tip(
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self.model_config.model, self.model_config.trust_remote_code
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)
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raise ValueError(
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f"{type(self.model)} does not support pipeline parallel. {tip}"
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)
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module_lists = []
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module_list_idx = None
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pp_plan = list(self.model._pp_plan.keys())
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for i, name in enumerate(pp_plan):
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if isinstance(getattr(self.model, name), nn.ModuleList):
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module_lists.append(name)
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module_list_idx = i
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if len(module_lists) > 1:
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raise ValueError(
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"Pipeline parallel of models with multiple `ModuleList`s "
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"in the base model are not supported yet!"
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)
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if module_list_idx is None:
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raise ValueError(f"Could not find `ModuleList` in {type(self.model)}")
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# Layers before module list
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for name in pp_plan[:module_list_idx]:
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if self.pp_group.is_first_rank or (
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self.text_config.tie_word_embeddings and self.pp_group.is_last_rank
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):
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continue
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setattr(self.model, name, PPMissingLayer())
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# Module list
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start_layer, end_layer = get_pp_indices(
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self.text_config.num_hidden_layers,
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self.pp_group.rank_in_group,
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self.pp_group.world_size,
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)
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layers_name = pp_plan[module_list_idx]
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layers = getattr(self.model, layers_name)
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for i in range(len(layers)):
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if start_layer <= i and i < end_layer:
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continue
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layers[i] = PPMissingLayer()
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# Layers after module list
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for name in pp_plan[module_list_idx + 1 :]:
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# Modules that should be on last rank
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if not self.pp_group.is_last_rank:
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setattr(self.model, name, PPMissingLayer())
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def recursive_replace(self):
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"""Recursively replace modules in the model as needed.
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Currently, this replaces:
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- `nn.Linear` with vLLM's tensor parallel linear classes
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- `*RMSNorm` with vLLM's `RMSNorm`
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"""
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tp_plan = self.model.tp_plan
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if not tp_plan and self.tp_group.world_size > 1:
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tip = get_feature_request_tip(
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self.model_config.model, self.model_config.trust_remote_code
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)
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raise ValueError(
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f"{type(self.model)} does not support tensor parallel. {tip}"
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)
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# Prefix the patterns because we always start from `self.model`
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tp_plan = {maybe_prefix("model", k): v for k, v in tp_plan.items()}
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def _recursive_replace(module: nn.Module, prefix: str):
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for child_name, child_module in module.named_children():
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new_module = child_module
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qual_name = maybe_prefix(prefix, child_name)
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if isinstance(child_module, nn.Linear):
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generator = (p for p in tp_plan if re.match(p, qual_name))
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pattern = next(generator, None)
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# Some weight loaders expect all linear layers to inherit
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# LinearBase, so we set a default style which causes any
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# unspecified layers to be replaced with ReplicatedLinear
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style = tp_plan.get(pattern, "replicate")
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new_module = replace_linear_class(
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child_module, style, self.quant_config, prefix=qual_name
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)
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elif child_module.__class__.__name__.endswith("RMSNorm"):
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new_module = replace_rms_norm_class(
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child_module, self.text_config.hidden_size
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)
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else:
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_recursive_replace(child_module, prefix=qual_name)
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if new_module is not child_module:
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setattr(module, child_name, new_module)
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log_replacement(qual_name, child_module, new_module)
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_recursive_replace(self.model, prefix="model")
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def create_attention_instances(self) -> dict[int, Attention]:
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"""
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Create `Attention` instances to inform KV cache allocation.
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"""
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text_config = self.text_config
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num_heads = self.model_config.get_num_attention_heads(self.parallel_config)
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head_size = self.model_config.get_head_size()
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num_kv_heads = self.model_config.get_num_kv_heads(self.parallel_config)
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logits_soft_cap = getattr(text_config, "attn_logit_softcapping", None)
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# In encoder models, the attention layers will have `is_causal=False`
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is_encoder = lambda module: not getattr(module, "is_causal", True)
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has_encoder = lambda model: any(is_encoder(m) for m in model.modules())
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is_multimodal = lambda config: config != config.get_text_config()
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# vLLM does not support encoder-decoder models, so if any encoder layer is
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# found in a text only model, we assume the whole model is an encoder model
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if has_encoder(self.model) and not is_multimodal(self.config):
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self.check_version("4.57.0.dev0", "encoder models support")
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attn_type = AttentionType.ENCODER_ONLY
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else:
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attn_type = AttentionType.DECODER
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pp_rank = self.pp_group.rank_in_group
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pp_size = self.pp_group.world_size
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start, end = get_pp_indices(text_config.num_hidden_layers, pp_rank, pp_size)
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attention_instances = {}
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for i in range(start, end):
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# Handle interleaved sliding window attention
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per_layer_sliding_window = None
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if (
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hasattr(self.config, "layer_types")
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and self.config.layer_types[i] == "sliding_attention"
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):
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per_layer_sliding_window = self.config.sliding_window
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attention_instances[i] = Attention(
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num_heads=num_heads,
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head_size=head_size,
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# NOTE: We use Llama scale as default, if it's set by
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# Transformers, it's updated in vllm_flash_attention_forward
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scale=head_size**-0.5,
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num_kv_heads=num_kv_heads,
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cache_config=self.cache_config,
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quant_config=self.quant_config,
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logits_soft_cap=logits_soft_cap,
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per_layer_sliding_window=per_layer_sliding_window,
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prefix=f"{i}.attn",
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attn_type=attn_type,
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)
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return attention_instances
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def init_parameters(self, module: nn.Module, dtype: torch.dtype | None = None):
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"""
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If a `parameter` is on the `meta` device, then its parent
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`module` is the original module created by:
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```python
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with torch.device("meta"):
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self.model: "PreTrainedModel" = AutoModel.from_config(...)
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```
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"""
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def _init_parameters(module: nn.Module, dtype: torch.dtype | None):
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for name, param in module.named_parameters(recurse=False):
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if param.device == torch.device("meta"):
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new_param = nn.Parameter(
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torch.empty_like(
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param.data,
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dtype=dtype or self.model_config.dtype,
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device=self.device_config.device,
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)
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)
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setattr(module, name, new_param)
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for child in module.children():
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_init_parameters(child, dtype)
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_init_parameters(module, dtype)
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def get_input_embeddings(self, input_ids: torch.Tensor) -> torch.Tensor:
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inputs_embeds = self.model.get_input_embeddings()(input_ids)
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if self.embed_scale is not None:
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inputs_embeds *= self.embed_scale
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return inputs_embeds
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def forward(
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self,
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input_ids: torch.Tensor | None,
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positions: torch.Tensor,
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intermediate_tensors: IntermediateTensors | None = None,
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inputs_embeds: torch.Tensor | None = None,
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**kwargs,
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) -> torch.Tensor | IntermediateTensors:
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if not self.pp_group.is_first_rank:
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assert intermediate_tensors is not None
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input_ids = None
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inputs_embeds = intermediate_tensors["hidden_states"]
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if input_ids is not None:
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input_ids = input_ids[None, ...]
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if inputs_embeds is not None:
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inputs_embeds = inputs_embeds[None, ...]
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# If the model scales embeddings inside the input embedding layer we must
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# ensure they are scaled here since VocabParallelEmbedding will not do it
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if (
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self.embed_scale is not None
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and input_ids is not None
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and inputs_embeds is None
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):
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inputs_embeds = self.get_input_embeddings(input_ids)
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input_ids = None
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if self.model_config.uses_mrope:
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position_ids = positions[:, None]
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else:
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position_ids = positions[None, ...]
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hidden_states = self.model(
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input_ids=input_ids,
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inputs_embeds=inputs_embeds,
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use_cache=False,
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position_ids=position_ids,
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attention_instances=self.attention_instances,
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return_dict=False,
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**kwargs,
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)[0][0, ...] # we remove batch dimension for now
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if not self.pp_group.is_last_rank:
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return IntermediateTensors({"hidden_states": hidden_states})
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return hidden_states
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def load_weights(
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self,
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weights: Iterable[tuple[str, torch.Tensor]],
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) -> set[str]:
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loader = AutoWeightsLoader(
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self,
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skip_prefixes=self.skip_prefixes,
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skip_substrs=self.skip_substrs,
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ignore_unexpected_prefixes=self.ignore_unexpected_prefixes,
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ignore_unexpected_suffixes=self.ignore_unexpected_suffixes,
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)
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return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)
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@staticmethod
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def check_version(min_version: str, feature: str):
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installed = Version(transformers.__version__)
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required = Version(min_version)
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if installed < required:
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raise ImportError(
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f"Transformers backend requires transformers>={required} "
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f"for {feature}, but got {installed}"
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)
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