library/sdxl_train_util.py

import argparse
import gc
import math
import os
from typing import Optional
import torch
from accelerate import init_empty_weights
from tqdm import tqdm
from transformers import CLIPTokenizer
from library import model_util, sdxl_model_util, train_util, sdxl_original_unet
from library.sdxl_lpw_stable_diffusion import SdxlStableDiffusionLongPromptWeightingPipeline

TOKENIZER1_PATH = "openai/clip-vit-large-patch14"
TOKENIZER2_PATH = "laion/CLIP-ViT-bigG-14-laion2B-39B-b160k"

DEFAULT_NOISE_OFFSET = 0.0357


def load_target_model(args, accelerator, model_version: str, weight_dtype):
    # load models for each process
    for pi in range(accelerator.state.num_processes):
        if pi == accelerator.state.local_process_index:
            print(f"loading model for process {accelerator.state.local_process_index}/{accelerator.state.num_processes}")

            (
                load_stable_diffusion_format,
                text_encoder1,
                text_encoder2,
                vae,
                unet,
                logit_scale,
                ckpt_info,
            ) = _load_target_model(
                args.pretrained_model_name_or_path,
                args.vae,
                model_version,
                weight_dtype,
                accelerator.device if args.lowram else "cpu",
            )

            # work on low-ram device
            if args.lowram:
                text_encoder1.to(accelerator.device)
                text_encoder2.to(accelerator.device)
                unet.to(accelerator.device)
                vae.to(accelerator.device)

            gc.collect()
            torch.cuda.empty_cache()
        accelerator.wait_for_everyone()

    text_encoder1, text_encoder2, unet = train_util.transform_models_if_DDP([text_encoder1, text_encoder2, unet])

    return load_stable_diffusion_format, text_encoder1, text_encoder2, vae, unet, logit_scale, ckpt_info


def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version: str, weight_dtype, device="cpu"):
    name_or_path = os.readlink(name_or_path) if os.path.islink(name_or_path) else name_or_path
    load_stable_diffusion_format = os.path.isfile(name_or_path)  # determine SD or Diffusers

    if load_stable_diffusion_format:
        print(f"load StableDiffusion checkpoint: {name_or_path}")
        (
            text_encoder1,
            text_encoder2,
            vae,
            unet,
            logit_scale,
            ckpt_info,
        ) = sdxl_model_util.load_models_from_sdxl_checkpoint(model_version, name_or_path, device, weight_dtype)
    else:
        # Diffusers model is loaded to CPU
        from diffusers import StableDiffusionXLPipeline

        variant = "fp16" if weight_dtype == torch.float16 else None
        print(f"load Diffusers pretrained models: {name_or_path}, variant={variant}")
        try:
            try:
                pipe = StableDiffusionXLPipeline.from_pretrained(
                    name_or_path, torch_dtype=weight_dtype, variant=variant, tokenizer=None
                )
            except EnvironmentError as ex:
                if variant is not None:
                    print("try to load fp32 model")
                    pipe = StableDiffusionXLPipeline.from_pretrained(name_or_path, variant=None, tokenizer=None)
                else:
                    raise ex
        except EnvironmentError as ex:
            print(
                f"model is not found as a file or in Hugging Face, perhaps file name is wrong? / 指定したモデル名のファイル、またはHugging Faceのモデルが見つかりません。ファイル名が誤っているかもしれません: {name_or_path}"
            )
            raise ex

        text_encoder1 = pipe.text_encoder
        text_encoder2 = pipe.text_encoder_2
        vae = pipe.vae
        unet = pipe.unet
        del pipe

        # Diffusers U-Net to original U-Net
        state_dict = sdxl_model_util.convert_diffusers_unet_state_dict_to_sdxl(unet.state_dict())
        with init_empty_weights():
            unet = sdxl_original_unet.SdxlUNet2DConditionModel()  # overwrite unet
        sdxl_model_util._load_state_dict_on_device(unet, state_dict, device=device)
        print("U-Net converted to original U-Net")

        logit_scale = None
        ckpt_info = None

    # VAEを読み込む
    if vae_path is not None:
        vae = model_util.load_vae(vae_path, weight_dtype)
        print("additional VAE loaded")

    return load_stable_diffusion_format, text_encoder1, text_encoder2, vae, unet, logit_scale, ckpt_info


def load_tokenizers(args: argparse.Namespace):
    print("prepare tokenizers")

    original_paths = [TOKENIZER1_PATH, TOKENIZER2_PATH]
    tokeniers = []
    for i, original_path in enumerate(original_paths):
        tokenizer: CLIPTokenizer = None
        if args.tokenizer_cache_dir:
            local_tokenizer_path = os.path.join(args.tokenizer_cache_dir, original_path.replace("/", "_"))
            if os.path.exists(local_tokenizer_path):
                print(f"load tokenizer from cache: {local_tokenizer_path}")
                tokenizer = CLIPTokenizer.from_pretrained(local_tokenizer_path)

        if tokenizer is None:
            tokenizer = CLIPTokenizer.from_pretrained(original_path)

        if args.tokenizer_cache_dir and not os.path.exists(local_tokenizer_path):
            print(f"save Tokenizer to cache: {local_tokenizer_path}")
            tokenizer.save_pretrained(local_tokenizer_path)

        if i == 1:
            tokenizer.pad_token_id = 0  # fix pad token id to make same as open clip tokenizer

        tokeniers.append(tokenizer)

    if hasattr(args, "max_token_length") and args.max_token_length is not None:
        print(f"update token length: {args.max_token_length}")

    return tokeniers


def timestep_embedding(timesteps, dim, max_period=10000):
    """
    Create sinusoidal timestep embeddings.
    :param timesteps: a 1-D Tensor of N indices, one per batch element.
                      These may be fractional.
    :param dim: the dimension of the output.
    :param max_period: controls the minimum frequency of the embeddings.
    :return: an [N x dim] Tensor of positional embeddings.
    """
    half = dim // 2
    freqs = torch.exp(-math.log(max_period) * torch.arange(start=0, end=half, dtype=torch.float32) / half).to(
        device=timesteps.device
    )
    args = timesteps[:, None].float() * freqs[None]
    embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
    if dim % 2:
        embedding = torch.cat([embedding, torch.zeros_like(embedding[:, :1])], dim=-1)
    return embedding


def get_timestep_embedding(x, outdim):
    assert len(x.shape) == 2
    b, dims = x.shape[0], x.shape[1]
    x = torch.flatten(x)
    emb = timestep_embedding(x, outdim)
    emb = torch.reshape(emb, (b, dims * outdim))
    return emb


def get_size_embeddings(orig_size, crop_size, target_size, device):
    emb1 = get_timestep_embedding(orig_size, 256)
    emb2 = get_timestep_embedding(crop_size, 256)
    emb3 = get_timestep_embedding(target_size, 256)
    vector = torch.cat([emb1, emb2, emb3], dim=1).to(device)
    return vector


def save_sd_model_on_train_end(
    args: argparse.Namespace,
    src_path: str,
    save_stable_diffusion_format: bool,
    use_safetensors: bool,
    save_dtype: torch.dtype,
    epoch: int,
    global_step: int,
    text_encoder1,
    text_encoder2,
    unet,
    vae,
    logit_scale,
    ckpt_info,
):
    def sd_saver(ckpt_file, epoch_no, global_step):
        sai_metadata = train_util.get_sai_model_spec(None, args, True, False, False, is_stable_diffusion_ckpt=True)
        sdxl_model_util.save_stable_diffusion_checkpoint(
            ckpt_file,
            text_encoder1,
            text_encoder2,
            unet,
            epoch_no,
            global_step,
            ckpt_info,
            vae,
            logit_scale,
            sai_metadata,
            save_dtype,
        )

    def diffusers_saver(out_dir):
        sdxl_model_util.save_diffusers_checkpoint(
            out_dir,
            text_encoder1,
            text_encoder2,
            unet,
            src_path,
            vae,
            use_safetensors=use_safetensors,
            save_dtype=save_dtype,
        )

    train_util.save_sd_model_on_train_end_common(
        args, save_stable_diffusion_format, use_safetensors, epoch, global_step, sd_saver, diffusers_saver
    )


# epochとstepの保存、メタデータにepoch/stepが含まれ引数が同じになるため、統合している
# on_epoch_end: Trueならepoch終了時、Falseならstep経過時
def save_sd_model_on_epoch_end_or_stepwise(
    args: argparse.Namespace,
    on_epoch_end: bool,
    accelerator,
    src_path,
    save_stable_diffusion_format: bool,
    use_safetensors: bool,
    save_dtype: torch.dtype,
    epoch: int,
    num_train_epochs: int,
    global_step: int,
    text_encoder1,
    text_encoder2,
    unet,
    vae,
    logit_scale,
    ckpt_info,
):
    def sd_saver(ckpt_file, epoch_no, global_step):
        sai_metadata = train_util.get_sai_model_spec(None, args, True, False, False, is_stable_diffusion_ckpt=True)
        sdxl_model_util.save_stable_diffusion_checkpoint(
            ckpt_file,
            text_encoder1,
            text_encoder2,
            unet,
            epoch_no,
            global_step,
            ckpt_info,
            vae,
            logit_scale,
            sai_metadata,
            save_dtype,
        )

    def diffusers_saver(out_dir):
        sdxl_model_util.save_diffusers_checkpoint(
            out_dir,
            text_encoder1,
            text_encoder2,
            unet,
            src_path,
            vae,
            use_safetensors=use_safetensors,
            save_dtype=save_dtype,
        )

    train_util.save_sd_model_on_epoch_end_or_stepwise_common(
        args,
        on_epoch_end,
        accelerator,
        save_stable_diffusion_format,
        use_safetensors,
        epoch,
        num_train_epochs,
        global_step,
        sd_saver,
        diffusers_saver,
    )


def add_sdxl_training_arguments(parser: argparse.ArgumentParser):
    parser.add_argument(
        "--cache_text_encoder_outputs", action="store_true", help="cache text encoder outputs / text encoderの出力をキャッシュする"
    )
    parser.add_argument(
        "--cache_text_encoder_outputs_to_disk",
        action="store_true",
        help="cache text encoder outputs to disk / text encoderの出力をディスクにキャッシュする",
    )


def verify_sdxl_training_args(args: argparse.Namespace, supportTextEncoderCaching: bool = True):
    assert not args.v2, "v2 cannot be enabled in SDXL training / SDXL学習ではv2を有効にすることはできません"
    if args.v_parameterization:
        print("v_parameterization will be unexpected / SDXL学習ではv_parameterizationは想定外の動作になります")

    if args.clip_skip is not None:
        print("clip_skip will be unexpected / SDXL学習ではclip_skipは動作しません")

    if args.multires_noise_iterations:
        print(
            f"Warning: SDXL has been trained with noise_offset={DEFAULT_NOISE_OFFSET}, but noise_offset is disabled due to multires_noise_iterations / SDXLはnoise_offset={DEFAULT_NOISE_OFFSET}で学習されていますが、multires_noise_iterationsが有効になっているためnoise_offsetは無効になります"
        )
    else:
        if args.noise_offset is None:
            args.noise_offset = DEFAULT_NOISE_OFFSET
        elif args.noise_offset != DEFAULT_NOISE_OFFSET:
            print(
                f"Warning: SDXL has been trained with noise_offset={DEFAULT_NOISE_OFFSET} / SDXLはnoise_offset={DEFAULT_NOISE_OFFSET}で学習されています"
            )
        print(f"noise_offset is set to {args.noise_offset} / noise_offsetが{args.noise_offset}に設定されました")

    assert (
        not hasattr(args, "weighted_captions") or not args.weighted_captions
    ), "weighted_captions cannot be enabled in SDXL training currently / SDXL学習では今のところweighted_captionsを有効にすることはできません"

    if supportTextEncoderCaching:
        if args.cache_text_encoder_outputs_to_disk and not args.cache_text_encoder_outputs:
            args.cache_text_encoder_outputs = True
            print(
                "cache_text_encoder_outputs is enabled because cache_text_encoder_outputs_to_disk is enabled / "
                + "cache_text_encoder_outputs_to_diskが有効になっているためcache_text_encoder_outputsが有効になりました"
            )


def sample_images(*args, **kwargs):
    return train_util.sample_images_common(SdxlStableDiffusionLongPromptWeightingPipeline, *args, **kwargs)