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vllm-omni/vllm_omni/diffusion/model_loader/diffusers_loader.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import dataclasses
import glob
import os
import time
from collections.abc import Generator, Iterable
from pathlib import Path
from typing import cast
import torch
from torch import nn
from vllm.config import ModelConfig
from vllm.config.load import LoadConfig
from vllm.logger import init_logger
from vllm.model_executor.layers.quantization.base_config import QuantizeMethodBase
from vllm.model_executor.model_loader.weight_utils import (
download_safetensors_index_file_from_hf,
download_weights_from_hf,
filter_duplicate_safetensors_files,
filter_files_not_needed_for_inference,
maybe_download_from_modelscope,
safetensors_weights_iterator,
)
from vllm.utils.import_utils import resolve_obj_by_qualname
from vllm.utils.torch_utils import set_default_torch_dtype
from vllm_omni.diffusion.data import OmniDiffusionConfig
from vllm_omni.diffusion.registry import initialize_model
logger = init_logger(__name__)
MODEL_INDEX = "model_index.json"
DIFFUSION_MODEL_WEIGHTS_INDEX = "diffusion_pytorch_model.safetensors.index.json"
class DiffusersPipelineLoader:
"""Model loader that can load diffusers pipeline components from disk."""
# default number of thread when enable multithread weight loading
DEFAULT_NUM_THREADS = 8
@dataclasses.dataclass
class ComponentSource:
"""A source for weights."""
model_or_path: str
"""The model ID or path."""
subfolder: str | None
"""The subfolder inside the model repo."""
revision: str | None
"""The optional model revision."""
prefix: str = ""
"""A prefix to prepend to all weights."""
fall_back_to_pt: bool = True
"""Whether .pt weights can be used."""
allow_patterns_overrides: list[str] | None = None
"""If defined, weights will load exclusively using these patterns."""
counter_before_loading_weights: float = 0.0
counter_after_loading_weights: float = 0.0
def __init__(self, load_config: LoadConfig):
self.load_config = load_config
# TODO(Isotr0py): Enable multithreaded weight loading
# extra_config = load_config.model_loader_extra_config
# allowed_keys = {"enable_multithread_load", "num_threads"}
# unexpected_keys = set(extra_config.keys()) - allowed_keys
# if unexpected_keys:
# raise ValueError(
# f"Unexpected extra config keys for load format {load_config.load_format}: {unexpected_keys}"
# )
def _prepare_weights(
self,
model_name_or_path: Path,
subfolder: str | None,
revision: str | None,
fall_back_to_pt: bool,
allow_patterns_overrides: list[str] | None,
) -> tuple[str, list[str], bool]:
"""Prepare weights for the model.
If the model is not local, it will be downloaded."""
model_name_or_path = maybe_download_from_modelscope(model_name_or_path, revision) or model_name_or_path
is_local = os.path.isdir(model_name_or_path)
load_format = self.load_config.load_format
use_safetensors = False
index_file = DIFFUSION_MODEL_WEIGHTS_INDEX
index_file_with_subfolder = f"{subfolder}/{index_file}" if subfolder else index_file
# only hf is supported currently
if load_format == "auto":
load_format = "hf"
# Some quantized models use .pt files for storing the weights.
if load_format == "hf":
allow_patterns = ["*.safetensors", "*.bin"]
else:
raise ValueError(f"Unknown load_format: {load_format}")
if fall_back_to_pt:
allow_patterns += ["*.pt"]
if allow_patterns_overrides is not None:
allow_patterns = allow_patterns_overrides
if subfolder is not None:
allow_patterns = [f"{subfolder}/{pattern}" for pattern in allow_patterns]
if not is_local:
hf_folder = download_weights_from_hf(
model_name_or_path,
self.load_config.download_dir,
allow_patterns,
revision,
ignore_patterns=self.load_config.ignore_patterns,
)
else:
hf_folder = model_name_or_path
hf_weights_files: list[str] = []
for pattern in allow_patterns:
hf_weights_files += glob.glob(os.path.join(hf_folder, pattern))
if len(hf_weights_files) > 0:
# Decide by actual files rather than pattern name (patterns may include subfolders).
use_safetensors = any(f.endswith(".safetensors") for f in hf_weights_files)
break
if use_safetensors:
# For models like Mistral-7B-Instruct-v0.3
# there are both sharded safetensors files and a consolidated
# safetensors file. Using both breaks.
# Here, we download the `model.safetensors.index.json` and filter
# any files not found in the index.
if not is_local:
download_safetensors_index_file_from_hf(
model_name_or_path,
index_file_with_subfolder,
self.load_config.download_dir,
revision,
)
# Some diffusers pipelines keep component weights under a
# subfolder (e.g. "transformer/") and the corresponding index file
# uses filenames relative to that subfolder. vLLM's
# `filter_duplicate_safetensors_files` expects weight_map entries
# to be relative to the `hf_folder` we pass in, so we point it to
# the component subfolder to avoid filtering out all shards.
filter_folder = os.path.join(hf_folder, subfolder) if subfolder is not None else hf_folder
hf_weights_files = filter_duplicate_safetensors_files(
hf_weights_files,
filter_folder,
index_file,
)
else:
hf_weights_files = filter_files_not_needed_for_inference(hf_weights_files)
if len(hf_weights_files) == 0:
raise RuntimeError(f"Cannot find any model weights with `{model_name_or_path}`")
return hf_folder, hf_weights_files, use_safetensors
def _get_weights_iterator(self, source: "ComponentSource") -> Generator[tuple[str, torch.Tensor], None, None]:
"""Get an iterator for the model weights based on the load format."""
hf_folder, hf_weights_files, use_safetensors = self._prepare_weights(
source.model_or_path,
source.subfolder,
source.revision,
source.fall_back_to_pt,
source.allow_patterns_overrides,
)
weights_iterator = safetensors_weights_iterator(
hf_weights_files,
self.load_config.use_tqdm_on_load,
self.load_config.safetensors_load_strategy,
)
if self.counter_before_loading_weights == 0.0:
self.counter_before_loading_weights = time.perf_counter()
# Apply the prefix.
return ((source.prefix + name, tensor) for (name, tensor) in weights_iterator)
def get_all_weights(
self,
model: nn.Module,
) -> Generator[tuple[str, torch.Tensor], None, None]:
sources = cast(
Iterable[DiffusersPipelineLoader.ComponentSource],
getattr(model, "weights_sources", ()),
)
for source in sources:
yield from self._get_weights_iterator(source)
def download_model(self, model_config: ModelConfig) -> None:
self._prepare_weights(
model_name_or_path=model_config.model,
subfolder=None,
revision=model_config.revision,
fall_back_to_pt=True,
allow_patterns_overrides=None,
)
def load_model(
self,
od_config: OmniDiffusionConfig,
load_device: str,
load_format: str = "default",
custom_pipeline_name: str | None = None,
) -> nn.Module:
"""Load a model with the given configurations."""
target_device = torch.device(load_device)
with set_default_torch_dtype(od_config.dtype):
with target_device:
if load_format == "default":
model = initialize_model(od_config)
elif load_format == "custom_pipeline":
model_cls = resolve_obj_by_qualname(custom_pipeline_name)
model = model_cls(od_config=od_config)
logger.debug("Loading weights on %s ...", load_device)
# Quantization does not happen in `load_weights` but after it
self.load_weights(model)
# Process weights after loading for quantization (e.g., FP8 online quantization)
# This is needed for vLLM's quantization methods that need to transform weights
self._process_weights_after_loading(model, target_device)
return model.eval()
def _process_weights_after_loading(self, model: nn.Module, target_device: torch.device) -> None:
"""Process weights after loading for quantization methods.
This handles vLLM's quantization methods that need to process weights
after loading (e.g., FP8 online quantization from BF16/FP16 weights).
"""
for _, module in model.named_modules():
quant_method = getattr(module, "quant_method", None)
if isinstance(quant_method, QuantizeMethodBase):
# Move module to target device for processing if needed
module_device = next(module.parameters(), None)
if module_device is not None:
module_device = module_device.device
needs_device_move = module_device != target_device
if needs_device_move:
module.to(target_device)
quant_method.process_weights_after_loading(module)
if needs_device_move:
module.to(module_device)
def load_weights(self, model: nn.Module) -> None:
weights_to_load = {name for name, _ in model.named_parameters()}
loaded_weights = model.load_weights(self.get_all_weights(model))
self.counter_after_loading_weights = time.perf_counter()
logger.info_once(
"Loading weights took %.2f seconds",
self.counter_after_loading_weights - self.counter_before_loading_weights,
)
# TODO(Isotr0py): Enable weights loading check after decoupling
# all components' weights loading (AutoModel.from_pretrained etc).
# We only enable strict check for non-quantized models
# that have loaded weights tracking currently.
if loaded_weights is not None:
_ = weights_to_load - loaded_weights
# if weights_not_loaded:
# raise ValueError(
# "Following weights were not initialized from "
# f"checkpoint: {weights_not_loaded}"
# )