train_network_recraft.py

import importlib
import argparse
import math
import os
import sys
import random
import time
import json
from multiprocessing import Value
from typing import Any, List
import toml

from tqdm import tqdm

import torch
from library.device_utils import init_ipex, clean_memory_on_device

init_ipex()

from accelerate.utils import set_seed
from diffusers import DDPMScheduler
from library import deepspeed_utils, model_util, strategy_base, strategy_sd

import library.train_util as train_util
from library.train_util import DreamBoothDataset
import library.config_util as config_util
from library.config_util import (
    ConfigSanitizer,
    BlueprintGenerator,
)
import library.huggingface_util as huggingface_util
import library.custom_train_functions as custom_train_functions
from library.custom_train_functions import (
    apply_snr_weight,
    get_weighted_text_embeddings,
    prepare_scheduler_for_custom_training,
    scale_v_prediction_loss_like_noise_prediction,
    add_v_prediction_like_loss,
    apply_debiased_estimation,
    apply_masked_loss,
)
from library.utils import setup_logging, add_logging_arguments

setup_logging()
import logging

logger = logging.getLogger(__name__)


class NetworkTrainer:
    def __init__(self):
        self.vae_scale_factor = 0.18215
        self.is_sdxl = False


    def generate_step_logs(
        self,
        args: argparse.Namespace,
        current_loss,
        avr_loss,
        lr_scheduler,
        lr_descriptions,
        keys_scaled=None,
        mean_norm=None,
        maximum_norm=None,
    ):
        logs = {"loss/current": current_loss, "loss/average": avr_loss}

        if keys_scaled is not None:
            logs["max_norm/keys_scaled"] = keys_scaled
            logs["max_norm/average_key_norm"] = mean_norm
            logs["max_norm/max_key_norm"] = maximum_norm

        lrs = lr_scheduler.get_last_lr()
        for i, lr in enumerate(lrs):
            if lr_descriptions is not None:
                lr_desc = lr_descriptions[i]
            else:
                idx = i - (0 if args.network_train_unet_only else -1)
                if idx == -1:
                    lr_desc = "textencoder"
                else:
                    if len(lrs) > 2:
                        lr_desc = f"group{idx}"
                    else:
                        lr_desc = "unet"

            logs[f"lr/{lr_desc}"] = lr

            if args.optimizer_type.lower().startswith("DAdapt".lower()) or args.optimizer_type.lower() == "Prodigy".lower():
                # tracking d*lr value
                logs[f"lr/d*lr/{lr_desc}"] = (
                    lr_scheduler.optimizers[-1].param_groups[i]["d"] * lr_scheduler.optimizers[-1].param_groups[i]["lr"]
                )

        return logs

    def assert_extra_args(self, args, train_dataset_group):
        train_dataset_group.verify_bucket_reso_steps(64)

    def load_target_model(self, args, weight_dtype, accelerator):
        text_encoder, vae, unet, _ = train_util.load_target_model(args, weight_dtype, accelerator)

        train_util.replace_unet_modules(unet, args.mem_eff_attn, args.xformers, args.sdpa)
        if torch.__version__ >= "2.0.0":  
            vae.set_use_memory_efficient_attention_xformers(args.xformers)

        return model_util.get_model_version_str_for_sd1_sd2(args.v2, args.v_parameterization), text_encoder, vae, unet

    def get_tokenize_strategy(self, args):
        return strategy_sd.SdTokenizeStrategy(args.v2, args.max_token_length, args.tokenizer_cache_dir)

    def get_tokenizers(self, tokenize_strategy: strategy_sd.SdTokenizeStrategy) -> List[Any]:
        return [tokenize_strategy.tokenizer]

    def get_latents_caching_strategy(self, args):
        latents_caching_strategy = strategy_sd.SdSdxlLatentsCachingStrategy(
            True, args.cache_latents_to_disk, args.vae_batch_size, args.skip_cache_check
        )
        return latents_caching_strategy

    def get_text_encoding_strategy(self, args):
        return strategy_sd.SdTextEncodingStrategy(args.clip_skip)

    def get_text_encoder_outputs_caching_strategy(self, args):
        return None

    def get_models_for_text_encoding(self, args, accelerator, text_encoders):
        """
        Returns a list of models that will be used for text encoding. SDXL uses wrapped and unwrapped models.
        FLUX.1 and SD3 may cache some outputs of the text encoder, so return the models that will be used for encoding (not cached).
        """
        return text_encoders

    # returns a list of bool values indicating whether each text encoder should be trained
    def get_text_encoders_train_flags(self, args, text_encoders):
        return [True] * len(text_encoders) if self.is_train_text_encoder(args) else [False] * len(text_encoders)

    def is_train_text_encoder(self, args):
        return not args.network_train_unet_only

    def cache_text_encoder_outputs_if_needed(self, args, accelerator, unet, vae, text_encoders, dataset, weight_dtype):
        for t_enc in text_encoders:
            t_enc.to(accelerator.device, dtype=weight_dtype)

    def call_unet(self, args, accelerator, unet, noisy_latents, timesteps, text_conds, batch, weight_dtype, **kwargs):
        noise_pred = unet(noisy_latents, timesteps, text_conds[0]).sample
        return noise_pred

    def all_reduce_network(self, accelerator, network):
        for param in network.parameters():
            if param.grad is not None:
                param.grad = accelerator.reduce(param.grad, reduction="mean")

    def sample_images(self, accelerator, args, epoch, global_step, device, vae, tokenizers, text_encoder, unet):
        train_util.sample_images(accelerator, args, epoch, global_step, device, vae, tokenizers[0], text_encoder, unet)

    # region SD/SDXL

    def post_process_network(self, args, accelerator, network, text_encoders, unet):
        pass

    def get_noise_scheduler(self, args: argparse.Namespace, device: torch.device) -> Any:
        noise_scheduler = DDPMScheduler(
            beta_start=0.00085, beta_end=0.012, beta_schedule="scaled_linear", num_train_timesteps=1000, clip_sample=False
        )
        prepare_scheduler_for_custom_training(noise_scheduler, device)
        if args.zero_terminal_snr:
            custom_train_functions.fix_noise_scheduler_betas_for_zero_terminal_snr(noise_scheduler)
        return noise_scheduler

    def encode_images_to_latents(self, args, accelerator, vae, images):
        return vae.encode(images).latent_dist.sample()

    def shift_scale_latents(self, args, latents):
        return latents * self.vae_scale_factor

    def get_noise_pred_and_target(
        self,
        args,
        accelerator,
        noise_scheduler,
        latents,
        batch,
        text_encoder_conds,
        unet,
        network,
        weight_dtype,
        train_unet,
    ):
        # Sample noise, sample a random timestep for each image, and add noise to the latents,
        # with noise offset and/or multires noise if specified
        noise, noisy_latents, timesteps, huber_c = train_util.get_noise_noisy_latents_and_timesteps(args, noise_scheduler, latents)

        # ensure the hidden state will require grad
        if args.gradient_checkpointing:
            for x in noisy_latents:
                x.requires_grad_(True)
            for t in text_encoder_conds:
                t.requires_grad_(True)

        # Predict the noise residual
        with accelerator.autocast():
            noise_pred = self.call_unet(
                args,
                accelerator,
                unet,
                noisy_latents.requires_grad_(train_unet),
                timesteps,
                text_encoder_conds,
                batch,
                weight_dtype,
            )

        if args.v_parameterization:
            # v-parameterization training
            target = noise_scheduler.get_velocity(latents, noise, timesteps)
        else:
            target = noise

        # differential output preservation
        if "custom_attributes" in batch:
            diff_output_pr_indices = []
            for i, custom_attributes in enumerate(batch["custom_attributes"]):
                if "diff_output_preservation" in custom_attributes and custom_attributes["diff_output_preservation"]:
                    diff_output_pr_indices.append(i)

            if len(diff_output_pr_indices) > 0:
                network.set_multiplier(0.0)
                with torch.no_grad(), accelerator.autocast():
                    noise_pred_prior = self.call_unet(
                        args,
                        accelerator,
                        unet,
                        noisy_latents,
                        timesteps,
                        text_encoder_conds,
                        batch,
                        weight_dtype,
                        indices=diff_output_pr_indices,
                    )
                network.set_multiplier(1.0)  # may be overwritten by "network_multipliers" in the next step
                target[diff_output_pr_indices] = noise_pred_prior.to(target.dtype)

        return noise_pred, target, timesteps, huber_c, None

    def post_process_loss(self, loss, args, timesteps, noise_scheduler):
        if args.min_snr_gamma:
            loss = apply_snr_weight(loss, timesteps, noise_scheduler, args.min_snr_gamma, args.v_parameterization)
        if args.scale_v_pred_loss_like_noise_pred:
            loss = scale_v_prediction_loss_like_noise_prediction(loss, timesteps, noise_scheduler)
        if args.v_pred_like_loss:
            loss = add_v_prediction_like_loss(loss, timesteps, noise_scheduler, args.v_pred_like_loss)
        if args.debiased_estimation_loss:
            loss = apply_debiased_estimation(loss, timesteps, noise_scheduler, args.v_parameterization)
        return loss

    def get_sai_model_spec(self, args):
        return train_util.get_sai_model_spec(None, args, self.is_sdxl, True, False)

    def update_metadata(self, metadata, args):
        pass

    def is_text_encoder_not_needed_for_training(self, args):
        return False  # use for sample images

    def prepare_text_encoder_grad_ckpt_workaround(self, index, text_encoder):
        # set top parameter requires_grad = True for gradient checkpointing works
        text_encoder.text_model.embeddings.requires_grad_(True)

    def prepare_text_encoder_fp8(self, index, text_encoder, te_weight_dtype, weight_dtype):
        text_encoder.text_model.embeddings.to(dtype=weight_dtype)

    def on_step_start(self, args, accelerator, network, text_encoders, unet, batch, weight_dtype):
        pass

    # endregion

    def train(self, args):
        session_id = random.randint(0, 2**32)
        training_started_at = time.time()
        train_util.verify_training_args(args)
        train_util.prepare_dataset_args(args, True)
        deepspeed_utils.prepare_deepspeed_args(args)
        setup_logging(args, reset=True)

        cache_latents = args.cache_latents
        use_dreambooth_method = args.in_json is None
        use_user_config = args.dataset_config is not None

        if args.seed is None:
            args.seed = random.randint(0, 2**32)
        set_seed(args.seed)

        tokenize_strategy = self.get_tokenize_strategy(args)
        strategy_base.TokenizeStrategy.set_strategy(tokenize_strategy)
        tokenizers = self.get_tokenizers(tokenize_strategy)  # will be removed after sample_image is refactored

        # prepare caching strategy: this must be set before preparing dataset. because dataset may use this strategy for initialization.
        latents_caching_strategy = self.get_latents_caching_strategy(args)
        strategy_base.LatentsCachingStrategy.set_strategy(latents_caching_strategy)


        if args.dataset_class is None:
            blueprint_generator = BlueprintGenerator(ConfigSanitizer(True, True, args.masked_loss, True))
            if use_user_config:
                logger.info(f"Loading dataset config from {args.dataset_config}")
                user_config = config_util.load_user_config(args.dataset_config)
                ignored = ["train_data_dir", "reg_data_dir", "in_json"]
                if any(getattr(args, attr) is not None for attr in ignored):
                    logger.warning(
                        "ignoring the following options because config file is found: {0} ".format(
                            ", ".join(ignored)
                        )
                    )
            else:
                if use_dreambooth_method:
                    logger.info("Using DreamBooth method.")
                    user_config = {
                        "datasets": [
                            {
                                "subsets": config_util.generate_dreambooth_subsets_config_by_subdirs(
                                    args.train_data_dir, args.reg_data_dir
                                )
                            }
                        ]
                    }
                else:
                    logger.info("Training with captions.")
                    user_config = {
                        "datasets": [
                            {
                                "subsets": [
                                    {
                                        "image_dir": args.train_data_dir,
                                        "metadata_file": args.in_json,
                                    }
                                ]
                            }
                        ]
                    }

            blueprint = blueprint_generator.generate(user_config, args)
            train_dataset_group = config_util.generate_dataset_group_by_blueprint(blueprint.dataset_group)
        else:
            # use arbitrary dataset class
            train_dataset_group = train_util.load_arbitrary_dataset(args)

        current_epoch = Value("i", 0)
        current_step = Value("i", 0)
        ds_for_collator = train_dataset_group if args.max_data_loader_n_workers == 0 else None
        collator = train_util.collator_class(current_epoch, current_step, ds_for_collator)

        if args.debug_dataset:
            train_dataset_group.set_current_strategies()  # dasaset needs to know the strategies explicitly
            train_util.debug_dataset(train_dataset_group)
            return
        if len(train_dataset_group) == 0:
            logger.error(
                "No data found. Please verify arguments (train_data_dir must be the parent of folders with images) "
            )
            return

        if cache_latents:
            assert (
                train_dataset_group.is_latent_cacheable()
            ), "when caching latents, either color_aug or random_crop cannot be used "

        self.assert_extra_args(args, train_dataset_group)  # may change some args

        # accelerator
        logger.info("preparing accelerator")
        accelerator = train_util.prepare_accelerator(args)
        is_main_process = accelerator.is_main_process

        # mixed precision
        weight_dtype, save_dtype = train_util.prepare_dtype(args)
        vae_dtype = torch.float32 if args.no_half_vae else weight_dtype


        model_version, text_encoder, vae, unet = self.load_target_model(args, weight_dtype, accelerator)

        # text_encoder is List[CLIPTextModel] or CLIPTextModel
        text_encoders = text_encoder if isinstance(text_encoder, list) else [text_encoder]


        sys.path.append(os.path.dirname(__file__))
        accelerator.print("import network module:", args.network_module)
        network_module = importlib.import_module(args.network_module)

        if args.base_weights is not None:
            # base_weights 
            for i, weight_path in enumerate(args.base_weights):
                if args.base_weights_multiplier is None or len(args.base_weights_multiplier) <= i:
                    multiplier = 1.0
                else:
                    multiplier = args.base_weights_multiplier[i]

                accelerator.print(f"merging module: {weight_path} with multiplier {multiplier}")

                module, weights_sd = network_module.create_network_from_weights(
                    multiplier, weight_path, vae, text_encoder, unet, for_inference=True
                )
                module.merge_to(text_encoder, unet, weights_sd, weight_dtype, accelerator.device if args.lowram else "cpu")

            accelerator.print(f"all weights merged: {', '.join(args.base_weights)}")


        if cache_latents:
            vae.to(accelerator.device, dtype=vae_dtype)
            vae.requires_grad_(False)
            vae.eval()

            train_dataset_group.new_cache_latents(vae, accelerator)

            vae.to("cpu")
            clean_memory_on_device(accelerator.device)

            accelerator.wait_for_everyone()

        
        # cache text encoder outputs if needed: Text Encoder is moved to cpu or gpu
        text_encoding_strategy = self.get_text_encoding_strategy(args)
        strategy_base.TextEncodingStrategy.set_strategy(text_encoding_strategy)

        text_encoder_outputs_caching_strategy = self.get_text_encoder_outputs_caching_strategy(args)
        if text_encoder_outputs_caching_strategy is not None:
            strategy_base.TextEncoderOutputsCachingStrategy.set_strategy(text_encoder_outputs_caching_strategy)
        self.cache_text_encoder_outputs_if_needed(args, accelerator, unet, vae, text_encoders, train_dataset_group, weight_dtype)

        # prepare network
        net_kwargs = {}
        if args.network_args is not None:
            for net_arg in args.network_args:
                key, value = net_arg.split("=")
                net_kwargs[key] = value

        # if a new network is added in future, add if ~ then blocks for each network (;'∀')
        if args.dim_from_weights:
            network, _ = network_module.create_network_from_weights(1, args.network_weights, vae, text_encoder, unet, **net_kwargs)
        else:
            if "dropout" not in net_kwargs:
                # workaround for LyCORIS (;^ω^)
                net_kwargs["dropout"] = args.network_dropout

            network = network_module.create_network(
                1.0,
                args.network_dim,
                args.network_alpha,
                vae,
                text_encoder,
                unet,
                neuron_dropout=args.network_dropout,
                **net_kwargs,
            )
        if network is None:
            return
        network_has_multiplier = hasattr(network, "set_multiplier")

        if hasattr(network, "prepare_network"):
            network.prepare_network(args)
        if args.scale_weight_norms and not hasattr(network, "apply_max_norm_regularization"):
            logger.warning(
                "warning: scale_weight_norms is specified but the network does not support it "
            )
            args.scale_weight_norms = False

        self.post_process_network(args, accelerator, network, text_encoders, unet)

        # apply network to unet and text_encoder
        train_unet = not args.network_train_text_encoder_only
        train_text_encoder = self.is_train_text_encoder(args)
        network.apply_to(text_encoder, unet, train_text_encoder, train_unet)

        if args.network_weights is not None:
            # FIXME consider alpha of weights: this assumes that the alpha is not changed
            info = network.load_weights(args.network_weights)
            accelerator.print(f"load network weights from {args.network_weights}: {info}")

        if args.gradient_checkpointing:
            if args.cpu_offload_checkpointing:
                unet.enable_gradient_checkpointing(cpu_offload=True)
            else:
                unet.enable_gradient_checkpointing()

            for t_enc, flag in zip(text_encoders, self.get_text_encoders_train_flags(args, text_encoders)):
                if flag:
                    if t_enc.supports_gradient_checkpointing:
                        t_enc.gradient_checkpointing_enable()
            del t_enc
            network.enable_gradient_checkpointing()  # may have no effect

        
        accelerator.print("prepare optimizer, data loader etc.")

        # make backward compatibility for text_encoder_lr
        support_multiple_lrs = hasattr(network, "prepare_optimizer_params_with_multiple_te_lrs")
        if support_multiple_lrs:
            text_encoder_lr = args.text_encoder_lr
        else:
            # toml backward compatibility
            if args.text_encoder_lr is None or isinstance(args.text_encoder_lr, float) or isinstance(args.text_encoder_lr, int):
                text_encoder_lr = args.text_encoder_lr
            else:
                text_encoder_lr = None if len(args.text_encoder_lr) == 0 else args.text_encoder_lr[0]
        try:
            if support_multiple_lrs:
                results = network.prepare_optimizer_params_with_multiple_te_lrs(text_encoder_lr, args.unet_lr, args.learning_rate)
            else:
                results = network.prepare_optimizer_params(text_encoder_lr, args.unet_lr, args.learning_rate)
            if type(results) is tuple:
                trainable_params = results[0]
                lr_descriptions = results[1]
            else:
                trainable_params = results
                lr_descriptions = None
        except TypeError as e:
            trainable_params = network.prepare_optimizer_params(text_encoder_lr, args.unet_lr)
            lr_descriptions = None

        # if len(trainable_params) == 0:
        #     accelerator.print("no trainable parameters found 
        # for params in trainable_params:
        #     for k, v in params.items():
        #         if type(v) == float:
        #             pass
        #         else:
        #             v = len(v)
        #         accelerator.print(f"trainable_params: {k} = {v}")

        optimizer_name, optimizer_args, optimizer = train_util.get_optimizer(args, trainable_params)
        optimizer_train_fn, optimizer_eval_fn = train_util.get_optimizer_train_eval_fn(optimizer, args)

        # prepare dataloader
        # strategies are set here because they cannot be referenced in another process. Copy them with the dataset
        # some strategies can be None
        train_dataset_group.set_current_strategies()

        # DataLoaderのプロセス数：0 は persistent_workers 
        n_workers = min(args.max_data_loader_n_workers, os.cpu_count())  # cpu_count or max_data_loader_n_workers

        train_dataloader = torch.utils.data.DataLoader(
            train_dataset_group,
            batch_size=1,
            shuffle=True,
            collate_fn=collator,
            num_workers=n_workers,
            persistent_workers=args.persistent_data_loader_workers,
        )

        
        if args.max_train_epochs is not None:
            args.max_train_steps = args.max_train_epochs * math.ceil(
                len(train_dataloader) / accelerator.num_processes / args.gradient_accumulation_steps
            )
            accelerator.print(
                f"override steps. steps for {args.max_train_epochs} epochs is "
            )

        
        train_dataset_group.set_max_train_steps(args.max_train_steps)

        # lr scheduler
        lr_scheduler = train_util.get_scheduler_fix(args, optimizer, accelerator.num_processes)

        
        if args.full_fp16:
            assert (
                args.mixed_precision == "fp16"
            ), "full_fp16 requires mixed precision='fp16' "
            accelerator.print("enable full fp16 training.")
            network.to(weight_dtype)
        elif args.full_bf16:
            assert (
                args.mixed_precision == "bf16"
            ), "full_bf16 requires mixed precision='bf16' "
            accelerator.print("enable full bf16 training.")
            network.to(weight_dtype)

        unet_weight_dtype = te_weight_dtype = weight_dtype
        # Experimental Feature: Put base model into fp8 to save vram
        if args.fp8_base or args.fp8_base_unet:
            assert torch.__version__ >= "2.1.0", "fp8_base requires torch>=2.1.0 "
            assert (
                args.mixed_precision != "no"
            ), "fp8_base requires mixed precision='fp16' or 'bf16' "
            accelerator.print("enable fp8 training for U-Net.")
            unet_weight_dtype = torch.float8_e4m3fn

            if not args.fp8_base_unet:
                accelerator.print("enable fp8 training for Text Encoder.")
            te_weight_dtype = weight_dtype if args.fp8_base_unet else torch.float8_e4m3fn

            # unet.to(accelerator.device)  # this makes faster `to(dtype)` below, but consumes 23 GB VRAM
            # unet.to(dtype=unet_weight_dtype)  # without moving to gpu, this takes a lot of time and main memory

            logger.info(f"set U-Net weight dtype to {unet_weight_dtype}, device to {accelerator.device}")
            unet.to(accelerator.device, dtype=unet_weight_dtype)  # this seems to be safer than above

        unet.requires_grad_(False)
        unet.to(dtype=unet_weight_dtype)
        for i, t_enc in enumerate(text_encoders):
            t_enc.requires_grad_(False)

            # in case of cpu, dtype is already set to fp32 because cpu does not support fp8/fp16/bf16
            if t_enc.device.type != "cpu":
                t_enc.to(dtype=te_weight_dtype)

                # nn.Embedding not support FP8
                if te_weight_dtype != weight_dtype:
                    self.prepare_text_encoder_fp8(i, t_enc, te_weight_dtype, weight_dtype)

        # accelerator
        if args.deepspeed:
            flags = self.get_text_encoders_train_flags(args, text_encoders)
            ds_model = deepspeed_utils.prepare_deepspeed_model(
                args,
                unet=unet if train_unet else None,
                text_encoder1=text_encoders[0] if flags[0] else None,
                text_encoder2=(text_encoders[1] if flags[1] else None) if len(text_encoders) > 1 else None,
                network=network,
            )
            ds_model, optimizer, train_dataloader, lr_scheduler = accelerator.prepare(
                ds_model, optimizer, train_dataloader, lr_scheduler
            )
            training_model = ds_model
        else:
            if train_unet:
                unet = accelerator.prepare(unet)
            else:
                unet.to(accelerator.device, dtype=unet_weight_dtype)  # move to device because unet is not prepared by accelerator
            if train_text_encoder:
                text_encoders = [
                    (accelerator.prepare(t_enc) if flag else t_enc)
                    for t_enc, flag in zip(text_encoders, self.get_text_encoders_train_flags(args, text_encoders))
                ]
                if len(text_encoders) > 1:
                    text_encoder = text_encoders
                else:
                    text_encoder = text_encoders[0]
            else:
                pass  # if text_encoder is not trained, no need to prepare. and device and dtype are already set

            network, optimizer, train_dataloader, lr_scheduler = accelerator.prepare(
                network, optimizer, train_dataloader, lr_scheduler
            )
            training_model = network

        if args.gradient_checkpointing:
            # according to TI example in Diffusers, train is required
            unet.train()
            for i, (t_enc, frag) in enumerate(zip(text_encoders, self.get_text_encoders_train_flags(args, text_encoders))):
                t_enc.train()

                # set top parameter requires_grad = True for gradient checkpointing works
                if frag:
                    self.prepare_text_encoder_grad_ckpt_workaround(i, t_enc)

        else:
            unet.eval()
            for t_enc in text_encoders:
                t_enc.eval()

        del t_enc

        accelerator.unwrap_model(network).prepare_grad_etc(text_encoder, unet)

        if not cache_latents: る
            vae.requires_grad_(False)
            vae.eval()
            vae.to(accelerator.device, dtype=vae_dtype)

        
        if args.full_fp16:
            train_util.patch_accelerator_for_fp16_training(accelerator)

        # before resuming make hook for saving/loading to save/load the network weights only
        def save_model_hook(models, weights, output_dir):
            # pop weights of other models than network to save only network weights
            # only main process or deepspeed https://github.com/huggingface/diffusers/issues/2606
            if accelerator.is_main_process or args.deepspeed:
                remove_indices = []
                for i, model in enumerate(models):
                    if not isinstance(model, type(accelerator.unwrap_model(network))):
                        remove_indices.append(i)
                for i in reversed(remove_indices):
                    if len(weights) > i:
                        weights.pop(i)
                # print(f"save model hook: {len(weights)} weights will be saved")

            # save current ecpoch and step
            train_state_file = os.path.join(output_dir, "train_state.json")
            # +1 is needed because the state is saved before current_step is set from global_step
            logger.info(f"save train state to {train_state_file} at epoch {current_epoch.value} step {current_step.value+1}")
            with open(train_state_file, "w", encoding="utf-8") as f:
                json.dump({"current_epoch": current_epoch.value, "current_step": current_step.value + 1}, f)

        steps_from_state = None

        def load_model_hook(models, input_dir):
            # remove models except network
            remove_indices = []
            for i, model in enumerate(models):
                if not isinstance(model, type(accelerator.unwrap_model(network))):
                    remove_indices.append(i)
            for i in reversed(remove_indices):
                models.pop(i)
            # print(f"load model hook: {len(models)} models will be loaded")

            # load current epoch and step to
            nonlocal steps_from_state
            train_state_file = os.path.join(input_dir, "train_state.json")
            if os.path.exists(train_state_file):
                with open(train_state_file, "r", encoding="utf-8") as f:
                    data = json.load(f)
                steps_from_state = data["current_step"]
                logger.info(f"load train state from {train_state_file}: {data}")

        accelerator.register_save_state_pre_hook(save_model_hook)
        accelerator.register_load_state_pre_hook(load_model_hook)

        # resume
        train_util.resume_from_local_or_hf_if_specified(accelerator, args)

        # epoch
        num_update_steps_per_epoch = math.ceil(len(train_dataloader) / args.gradient_accumulation_steps)
        num_train_epochs = math.ceil(args.max_train_steps / num_update_steps_per_epoch)
        if (args.save_n_epoch_ratio is not None) and (args.save_n_epoch_ratio > 0):
            args.save_every_n_epochs = math.floor(num_train_epochs / args.save_n_epoch_ratio) or 1


        # TODO: find a way to handle total batch size when there are multiple datasets
        total_batch_size = args.train_batch_size * accelerator.num_processes * args.gradient_accumulation_steps

        accelerator.print("running training ")
        accelerator.print(f"  num train images * repeats : {train_dataset_group.num_train_images}")
        accelerator.print(f"  num reg images : {train_dataset_group.num_reg_images}")
        accelerator.print(f"  num batches per epoch : {len(train_dataloader)}")
        accelerator.print(f"  num epochs: {num_train_epochs}")
        accelerator.print(
            f"  batch size per device / バッチサイズ: {', '.join([str(d.batch_size) for d in train_dataset_group.datasets])}"
        )
        # accelerator.print(f"  total train batch size (with parallel & distributed & accumulation): {total_batch_size}")
        accelerator.print(f"  gradient accumulation steps = {args.gradient_accumulation_steps}")
        accelerator.print(f"  total optimization steps : {args.max_train_steps}")

        # TODO refactor metadata creation and move to util
        metadata = {
            "ss_session_id": session_id,  # random integer indicating which group of epochs the model came from
            "ss_training_started_at": training_started_at,  # unix timestamp
            "ss_output_name": args.output_name,
            "ss_learning_rate": args.learning_rate,
            "ss_text_encoder_lr": text_encoder_lr,
            "ss_unet_lr": args.unet_lr,
            "ss_num_train_images": train_dataset_group.num_train_images,
            "ss_num_reg_images": train_dataset_group.num_reg_images,
            "ss_num_batches_per_epoch": len(train_dataloader),
            "ss_num_epochs": num_train_epochs,
            "ss_gradient_checkpointing": args.gradient_checkpointing,
            "ss_gradient_accumulation_steps": args.gradient_accumulation_steps,
            "ss_max_train_steps": args.max_train_steps,
            "ss_lr_warmup_steps": args.lr_warmup_steps,
            "ss_lr_scheduler": args.lr_scheduler,
            "ss_network_module": args.network_module,
            "ss_network_dim": args.network_dim,  # None means default because another network than LoRA may have another default dim
            "ss_network_alpha": args.network_alpha,  # some networks may not have alpha
            "ss_network_dropout": args.network_dropout,  # some networks may not have dropout
            "ss_mixed_precision": args.mixed_precision,
            "ss_full_fp16": bool(args.full_fp16),
            "ss_v2": bool(args.v2),
            "ss_base_model_version": model_version,
            "ss_clip_skip": args.clip_skip,
            "ss_max_token_length": args.max_token_length,
            "ss_cache_latents": bool(args.cache_latents),
            "ss_seed": args.seed,
            "ss_lowram": args.lowram,
            "ss_noise_offset": args.noise_offset,
            "ss_multires_noise_iterations": args.multires_noise_iterations,
            "ss_multires_noise_discount": args.multires_noise_discount,
            "ss_adaptive_noise_scale": args.adaptive_noise_scale,
            "ss_zero_terminal_snr": args.zero_terminal_snr,
            "ss_training_comment": args.training_comment,  # will not be updated after training
            "ss_sd_scripts_commit_hash": train_util.get_git_revision_hash(),
            "ss_optimizer": optimizer_name + (f"({optimizer_args})" if len(optimizer_args) > 0 else ""),
            "ss_max_grad_norm": args.max_grad_norm,
            "ss_caption_dropout_rate": args.caption_dropout_rate,
            "ss_caption_dropout_every_n_epochs": args.caption_dropout_every_n_epochs,
            "ss_caption_tag_dropout_rate": args.caption_tag_dropout_rate,
            "ss_face_crop_aug_range": args.face_crop_aug_range,
            "ss_prior_loss_weight": args.prior_loss_weight,
            "ss_min_snr_gamma": args.min_snr_gamma,
            "ss_scale_weight_norms": args.scale_weight_norms,
            "ss_ip_noise_gamma": args.ip_noise_gamma,
            "ss_debiased_estimation": bool(args.debiased_estimation_loss),
            "ss_noise_offset_random_strength": args.noise_offset_random_strength,
            "ss_ip_noise_gamma_random_strength": args.ip_noise_gamma_random_strength,
            "ss_loss_type": args.loss_type,
            "ss_huber_schedule": args.huber_schedule,
            "ss_huber_c": args.huber_c,
            "ss_fp8_base": bool(args.fp8_base),
            "ss_fp8_base_unet": bool(args.fp8_base_unet),
        }

        self.update_metadata(metadata, args)  # architecture specific metadata

        if use_user_config:
            # save metadata of multiple datasets
            # NOTE: pack "ss_datasets" value as json one time
            #   or should also pack nested collections as json?
            datasets_metadata = []
            tag_frequency = {}  # merge tag frequency for metadata editor
            dataset_dirs_info = {}  # merge subset dirs for metadata editor

            for dataset in train_dataset_group.datasets:
                is_dreambooth_dataset = isinstance(dataset, DreamBoothDataset)
                dataset_metadata = {
                    "is_dreambooth": is_dreambooth_dataset,
                    "batch_size_per_device": dataset.batch_size,
                    "num_train_images": dataset.num_train_images,  # includes repeating
                    "num_reg_images": dataset.num_reg_images,
                    "resolution": (dataset.width, dataset.height),
                    "enable_bucket": bool(dataset.enable_bucket),
                    "min_bucket_reso": dataset.min_bucket_reso,
                    "max_bucket_reso": dataset.max_bucket_reso,
                    "tag_frequency": dataset.tag_frequency,
                    "bucket_info": dataset.bucket_info,
                }

                subsets_metadata = []
                for subset in dataset.subsets:
                    subset_metadata = {
                        "img_count": subset.img_count,
                        "num_repeats": subset.num_repeats,
                        "color_aug": bool(subset.color_aug),
                        "flip_aug": bool(subset.flip_aug),
                        "random_crop": bool(subset.random_crop),
                        "shuffle_caption": bool(subset.shuffle_caption),
                        "keep_tokens": subset.keep_tokens,
                        "keep_tokens_separator": subset.keep_tokens_separator,
                        "secondary_separator": subset.secondary_separator,
                        "enable_wildcard": bool(subset.enable_wildcard),
                        "caption_prefix": subset.caption_prefix,
                        "caption_suffix": subset.caption_suffix,
                    }

                    image_dir_or_metadata_file = None
                    if subset.image_dir:
                        image_dir = os.path.basename(subset.image_dir)
                        subset_metadata["image_dir"] = image_dir
                        image_dir_or_metadata_file = image_dir

                    if is_dreambooth_dataset:
                        subset_metadata["class_tokens"] = subset.class_tokens
                        subset_metadata["is_reg"] = subset.is_reg
                        if subset.is_reg:
                            image_dir_or_metadata_file = None  # not merging reg dataset
                    else:
                        metadata_file = os.path.basename(subset.metadata_file)
                        subset_metadata["metadata_file"] = metadata_file
                        image_dir_or_metadata_file = metadata_file  # may overwrite

                    subsets_metadata.append(subset_metadata)

                    # merge dataset dir: not reg subset only
                    # TODO update additional-network extension to show detailed dataset config from metadata
                    if image_dir_or_metadata_file is not None:
                        # datasets may have a certain dir multiple times
                        v = image_dir_or_metadata_file
                        i = 2
                        while v in dataset_dirs_info:
                            v = image_dir_or_metadata_file + f" ({i})"
                            i += 1
                        image_dir_or_metadata_file = v

                        dataset_dirs_info[image_dir_or_metadata_file] = {
                            "n_repeats": subset.num_repeats,
                            "img_count": subset.img_count,
                        }

                dataset_metadata["subsets"] = subsets_metadata
                datasets_metadata.append(dataset_metadata)

                # merge tag frequency:
                for ds_dir_name, ds_freq_for_dir in dataset.tag_frequency.items():

                    if ds_dir_name in tag_frequency:
                        continue
                    tag_frequency[ds_dir_name] = ds_freq_for_dir

            metadata["ss_datasets"] = json.dumps(datasets_metadata)
            metadata["ss_tag_frequency"] = json.dumps(tag_frequency)
            metadata["ss_dataset_dirs"] = json.dumps(dataset_dirs_info)
        else:
            # conserving backward compatibility when using train_dataset_dir and reg_dataset_dir
            assert (
                len(train_dataset_group.datasets) == 1
            ), f"There should be a single dataset but {len(train_dataset_group.datasets)} found. This seems to be a bug."

            dataset = train_dataset_group.datasets[0]

            dataset_dirs_info = {}
            reg_dataset_dirs_info = {}
            if use_dreambooth_method:
                for subset in dataset.subsets:
                    info = reg_dataset_dirs_info if subset.is_reg else dataset_dirs_info
                    info[os.path.basename(subset.image_dir)] = {"n_repeats": subset.num_repeats, "img_count": subset.img_count}
            else:
                for subset in dataset.subsets:
                    dataset_dirs_info[os.path.basename(subset.metadata_file)] = {
                        "n_repeats": subset.num_repeats,
                        "img_count": subset.img_count,
                    }

            metadata.update(
                {
                    "ss_batch_size_per_device": args.train_batch_size,
                    "ss_total_batch_size": total_batch_size,
                    "ss_resolution": args.resolution,
                    "ss_color_aug": bool(args.color_aug),
                    "ss_flip_aug": bool(args.flip_aug),
                    "ss_random_crop": bool(args.random_crop),
                    "ss_shuffle_caption": bool(args.shuffle_caption),
                    "ss_enable_bucket": bool(dataset.enable_bucket),
                    "ss_bucket_no_upscale": bool(dataset.bucket_no_upscale),
                    "ss_min_bucket_reso": dataset.min_bucket_reso,
                    "ss_max_bucket_reso": dataset.max_bucket_reso,
                    "ss_keep_tokens": args.keep_tokens,
                    "ss_dataset_dirs": json.dumps(dataset_dirs_info),
                    "ss_reg_dataset_dirs": json.dumps(reg_dataset_dirs_info),
                    "ss_tag_frequency": json.dumps(dataset.tag_frequency),
                    "ss_bucket_info": json.dumps(dataset.bucket_info),
                }
            )

        # add extra args
        if args.network_args:
            metadata["ss_network_args"] = json.dumps(net_kwargs)

        # model name and hash
        if args.pretrained_model_name_or_path is not None:
            sd_model_name = args.pretrained_model_name_or_path
            if os.path.exists(sd_model_name):
                metadata["ss_sd_model_hash"] = train_util.model_hash(sd_model_name)
                metadata["ss_new_sd_model_hash"] = train_util.calculate_sha256(sd_model_name)
                sd_model_name = os.path.basename(sd_model_name)
            metadata["ss_sd_model_name"] = sd_model_name

        if args.vae is not None:
            vae_name = args.vae
            if os.path.exists(vae_name):
                metadata["ss_vae_hash"] = train_util.model_hash(vae_name)
                metadata["ss_new_vae_hash"] = train_util.calculate_sha256(vae_name)
                vae_name = os.path.basename(vae_name)
            metadata["ss_vae_name"] = vae_name

        metadata = {k: str(v) for k, v in metadata.items()}

        # make minimum metadata for filtering
        minimum_metadata = {}
        for key in train_util.SS_METADATA_MINIMUM_KEYS:
            if key in metadata:
                minimum_metadata[key] = metadata[key]

        # calculate steps to skip when resuming or starting from a specific step
        initial_step = 0
        if args.initial_epoch is not None or args.initial_step is not None:
            # if initial_epoch or initial_step is specified, steps_from_state is ignored even when resuming
            if steps_from_state is not None:
                logger.warning(
                    "steps from the state is ignored because initial_step is specified "
                )
            if args.initial_step is not None:
                initial_step = args.initial_step
            else:
                # num steps per epoch is calculated by num_processes and gradient_accumulation_steps
                initial_step = (args.initial_epoch - 1) * math.ceil(
                    len(train_dataloader) / accelerator.num_processes / args.gradient_accumulation_steps
                )
        else:
            # if initial_epoch and initial_step are not specified, steps_from_state is used when resuming
            if steps_from_state is not None:
                initial_step = steps_from_state
                steps_from_state = None

        if initial_step > 0:
            assert (
                args.max_train_steps > initial_step
            ), f"max_train_steps should be greater than initial step "

        progress_bar = tqdm(
            range(args.max_train_steps - initial_step), smoothing=0, disable=not accelerator.is_local_main_process, desc="steps"
        )

        epoch_to_start = 0
        if initial_step > 0:
            if args.skip_until_initial_step:
                # if skip_until_initial_step is specified, load data and discard it to ensure the same data is used
                if not args.resume:
                    logger.info(
                        f"initial_step is specified but not resuming. lr scheduler will be started from the beginning"
                    )
                logger.info(f"skipping {initial_step} steps")
                initial_step *= args.gradient_accumulation_steps

                # set epoch to start to make initial_step less than len(train_dataloader)
                epoch_to_start = initial_step // math.ceil(len(train_dataloader) / args.gradient_accumulation_steps)
            else:
                # if not, only epoch no is skipped for informative purpose
                epoch_to_start = initial_step // math.ceil(len(train_dataloader) / args.gradient_accumulation_steps)
                initial_step = 0  # do not skip

        global_step = 0

        noise_scheduler = self.get_noise_scheduler(args, accelerator.device)

        if accelerator.is_main_process:
            init_kwargs = {}
            if args.wandb_run_name:
                init_kwargs["wandb"] = {"name": args.wandb_run_name}
            if args.log_tracker_config is not None:
                init_kwargs = toml.load(args.log_tracker_config)
            accelerator.init_trackers(
                "network_train" if args.log_tracker_name is None else args.log_tracker_name,
                config=train_util.get_sanitized_config_or_none(args),
                init_kwargs=init_kwargs,
            )

        loss_recorder = train_util.LossRecorder()
        del train_dataset_group

        # callback for step start
        if hasattr(accelerator.unwrap_model(network), "on_step_start"):
            on_step_start_for_network = accelerator.unwrap_model(network).on_step_start
        else:
            on_step_start_for_network = lambda *args, **kwargs: None

        # function for saving/removing
        def save_model(ckpt_name, unwrapped_nw, steps, epoch_no, force_sync_upload=False):
            os.makedirs(args.output_dir, exist_ok=True)
            ckpt_file = os.path.join(args.output_dir, ckpt_name)

            accelerator.print(f"\nsaving checkpoint: {ckpt_file}")
            metadata["ss_training_finished_at"] = str(time.time())
            metadata["ss_steps"] = str(steps)
            metadata["ss_epoch"] = str(epoch_no)

            metadata_to_save = minimum_metadata if args.no_metadata else metadata
            sai_metadata = self.get_sai_model_spec(args)
            metadata_to_save.update(sai_metadata)

            unwrapped_nw.save_weights(ckpt_file, save_dtype, metadata_to_save)
            if args.huggingface_repo_id is not None:
                huggingface_util.upload(args, ckpt_file, "/" + ckpt_name, force_sync_upload=force_sync_upload)

        def remove_model(old_ckpt_name):
            old_ckpt_file = os.path.join(args.output_dir, old_ckpt_name)
            if os.path.exists(old_ckpt_file):
                accelerator.print(f"removing old checkpoint: {old_ckpt_file}")
                os.remove(old_ckpt_file)

        # if text_encoder is not needed for training, delete it to save memory.
        # TODO this can be automated after SDXL sample prompt cache is implemented
        if self.is_text_encoder_not_needed_for_training(args):
            logger.info("text_encoder is not needed for training. deleting to save memory.")
            for t_enc in text_encoders:
                del t_enc
            text_encoders = []
            text_encoder = None

        # For --sample_at_first
        optimizer_eval_fn()
        self.sample_images(accelerator, args, 0, global_step, accelerator.device, vae, tokenizers, text_encoder, unet)
        optimizer_train_fn()
        if len(accelerator.trackers) > 0:
            # log empty object to commit the sample images to wandb
            accelerator.log({}, step=0)

        # training loop
        if initial_step > 0:  # only if skip_until_initial_step is specified
            for skip_epoch in range(epoch_to_start):  # skip epochs
                logger.info(f"skipping epoch {skip_epoch+1} because initial_step (multiplied) is {initial_step}")
                initial_step -= len(train_dataloader)
            global_step = initial_step

        # log device and dtype for each model
        logger.info(f"unet dtype: {unet_weight_dtype}, device: {unet.device}")
        for i, t_enc in enumerate(text_encoders):
            params_itr = t_enc.parameters()
            params_itr.__next__()  # skip the first parameter
            params_itr.__next__()  # skip the second parameter. because CLIP first two parameters are embeddings
            param_3rd = params_itr.__next__()
            logger.info(f"text_encoder [{i}] dtype: {param_3rd.dtype}, device: {t_enc.device}")

        clean_memory_on_device(accelerator.device)

        for epoch in range(epoch_to_start, num_train_epochs):
            accelerator.print(f"\nepoch {epoch+1}/{num_train_epochs}")
            current_epoch.value = epoch + 1

            metadata["ss_epoch"] = str(epoch + 1)

            accelerator.unwrap_model(network).on_epoch_start(text_encoder, unet)

            skipped_dataloader = None
            if initial_step > 0:
                skipped_dataloader = accelerator.skip_first_batches(train_dataloader, initial_step - 1)
                initial_step = 1

            for step, batch in enumerate(skipped_dataloader or train_dataloader):
                current_step.value = global_step
                if initial_step > 0:
                    initial_step -= 1
                    continue

                with accelerator.accumulate(training_model):
                    on_step_start_for_network(text_encoder, unet)

                    # temporary, for batch processing
                    self.on_step_start(args, accelerator, network, text_encoders, unet, batch, weight_dtype)

                    if "latents" in batch and batch["latents"] is not None:
                        latents = batch["latents"].to(accelerator.device).to(dtype=weight_dtype)
                    else:
                        with torch.no_grad():
                            # latentに変換
                            latents = self.encode_images_to_latents(args, accelerator, vae, batch["images"].to(vae_dtype))
                            latents = latents.to(dtype=weight_dtype)

                            
                            if torch.any(torch.isnan(latents)):
                                accelerator.print("NaN found in latents, replacing with zeros")
                                latents = torch.nan_to_num(latents, 0, out=latents)

                    latents = self.shift_scale_latents(args, latents)

                    # get multiplier for each sample
                    if network_has_multiplier:
                        multipliers = batch["network_multipliers"]
                        # if all multipliers are same, use single multiplier
                        if torch.all(multipliers == multipliers[0]):
                            multipliers = multipliers[0].item()
                        else:
                            raise NotImplementedError("multipliers for each sample is not supported yet")
                        # print(f"set multiplier: {multipliers}")
                        accelerator.unwrap_model(network).set_multiplier(multipliers)

                    text_encoder_conds = []
                    text_encoder_outputs_list = batch.get("text_encoder_outputs_list", None)
                    if text_encoder_outputs_list is not None:
                        text_encoder_conds = text_encoder_outputs_list  # List of text encoder outputs

                    if len(text_encoder_conds) == 0 or text_encoder_conds[0] is None or train_text_encoder:
                        # TODO this does not work if 'some text_encoders are trained' and 'some are not and not cached'
                        with torch.set_grad_enabled(train_text_encoder), accelerator.autocast():
                            # Get the text embedding for conditioning
                            if args.weighted_captions:
                                input_ids_list, weights_list = tokenize_strategy.tokenize_with_weights(batch["captions"])
                                encoded_text_encoder_conds = text_encoding_strategy.encode_tokens_with_weights(
                                    tokenize_strategy,
                                    self.get_models_for_text_encoding(args, accelerator, text_encoders),
                                    input_ids_list,
                                    weights_list,
                                )
                            else:
                                input_ids = [ids.to(accelerator.device) for ids in batch["input_ids_list"]]
                                encoded_text_encoder_conds = text_encoding_strategy.encode_tokens(
                                    tokenize_strategy,
                                    self.get_models_for_text_encoding(args, accelerator, text_encoders),
                                    input_ids,
                                )
                            if args.full_fp16:
                                encoded_text_encoder_conds = [c.to(weight_dtype) for c in encoded_text_encoder_conds]

                        # if text_encoder_conds is not cached, use encoded_text_encoder_conds
                        if len(text_encoder_conds) == 0:
                            text_encoder_conds = encoded_text_encoder_conds
                        else:
                            # if encoded_text_encoder_conds is not None, update cached text_encoder_conds
                            for i in range(len(encoded_text_encoder_conds)):
                                if encoded_text_encoder_conds[i] is not None:
                                    text_encoder_conds[i] = encoded_text_encoder_conds[i]

                    # sample noise, call unet, get target
                    noise_pred, target, timesteps, huber_c, weighting = self.get_noise_pred_and_target(
                        args,
                        accelerator,
                        noise_scheduler,
                        latents,
                        batch,
                        text_encoder_conds,
                        unet,
                        network,
                        weight_dtype,
                        train_unet,
                    )

                    loss = train_util.conditional_loss(
                        noise_pred.float(), target.float(), reduction="none", loss_type=args.loss_type, huber_c=huber_c
                    )
                    if weighting is not None:
                        loss = loss * weighting
                    if args.masked_loss or ("alpha_masks" in batch and batch["alpha_masks"] is not None):
                        loss = apply_masked_loss(loss, batch)
                    loss = loss.mean([1, 2, 3])

                    loss_weights = batch["loss_weights"]  
                    loss = loss * loss_weights

                    # min snr gamma, scale v pred loss like noise pred, v pred like loss, debiased estimation etc.
                    loss = self.post_process_loss(loss, args, timesteps, noise_scheduler)

                    loss = loss.mean() 

                    accelerator.backward(loss)
                    if accelerator.sync_gradients:
                        self.all_reduce_network(accelerator, network)  # sync DDP grad manually
                        if args.max_grad_norm != 0.0:
                            params_to_clip = accelerator.unwrap_model(network).get_trainable_params()
                            accelerator.clip_grad_norm_(params_to_clip, args.max_grad_norm)

                    optimizer.step()
                    lr_scheduler.step()
                    optimizer.zero_grad(set_to_none=True)

                if args.scale_weight_norms:
                    keys_scaled, mean_norm, maximum_norm = accelerator.unwrap_model(network).apply_max_norm_regularization(
                        args.scale_weight_norms, accelerator.device
                    )
                    max_mean_logs = {"Keys Scaled": keys_scaled, "Average key norm": mean_norm}
                else:
                    keys_scaled, mean_norm, maximum_norm = None, None, None

                # Checks if the accelerator has performed an optimization step behind the scenes
                if accelerator.sync_gradients:
                    progress_bar.update(1)
                    global_step += 1

                    optimizer_eval_fn()
                    self.sample_images(
                        accelerator, args, None, global_step, accelerator.device, vae, tokenizers, text_encoder, unet
                    )

                    
                    if args.save_every_n_steps is not None and global_step % args.save_every_n_steps == 0:
                        accelerator.wait_for_everyone()
                        if accelerator.is_main_process:
                            ckpt_name = train_util.get_step_ckpt_name(args, "." + args.save_model_as, global_step)
                            save_model(ckpt_name, accelerator.unwrap_model(network), global_step, epoch)

                            if args.save_state:
                                train_util.save_and_remove_state_stepwise(args, accelerator, global_step)

                            remove_step_no = train_util.get_remove_step_no(args, global_step)
                            if remove_step_no is not None:
                                remove_ckpt_name = train_util.get_step_ckpt_name(args, "." + args.save_model_as, remove_step_no)
                                remove_model(remove_ckpt_name)
                    optimizer_train_fn()

                current_loss = loss.detach().item()
                loss_recorder.add(epoch=epoch, step=step, loss=current_loss)
                avr_loss: float = loss_recorder.moving_average
                logs = {"avr_loss": avr_loss}  # , "lr": lr_scheduler.get_last_lr()[0]}
                progress_bar.set_postfix(**logs)

                if args.scale_weight_norms:
                    progress_bar.set_postfix(**{**max_mean_logs, **logs})

                if len(accelerator.trackers) > 0:
                    logs = self.generate_step_logs(
                        args, current_loss, avr_loss, lr_scheduler, lr_descriptions, keys_scaled, mean_norm, maximum_norm
                    )
                    accelerator.log(logs, step=global_step)

                if global_step >= args.max_train_steps:
                    break

            if len(accelerator.trackers) > 0:
                logs = {"loss/epoch": loss_recorder.moving_average}
                accelerator.log(logs, step=epoch + 1)

            accelerator.wait_for_everyone()

            
            optimizer_eval_fn()
            if args.save_every_n_epochs is not None:
                saving = (epoch + 1) % args.save_every_n_epochs == 0 and (epoch + 1) < num_train_epochs
                if is_main_process and saving:
                    ckpt_name = train_util.get_epoch_ckpt_name(args, "." + args.save_model_as, epoch + 1)
                    save_model(ckpt_name, accelerator.unwrap_model(network), global_step, epoch + 1)

                    remove_epoch_no = train_util.get_remove_epoch_no(args, epoch + 1)
                    if remove_epoch_no is not None:
                        remove_ckpt_name = train_util.get_epoch_ckpt_name(args, "." + args.save_model_as, remove_epoch_no)
                        remove_model(remove_ckpt_name)

                    if args.save_state:
                        train_util.save_and_remove_state_on_epoch_end(args, accelerator, epoch + 1)

            self.sample_images(accelerator, args, epoch + 1, global_step, accelerator.device, vae, tokenizers, text_encoder, unet)
            optimizer_train_fn()

            # end of epoch

        # metadata["ss_epoch"] = str(num_train_epochs)
        metadata["ss_training_finished_at"] = str(time.time())

        if is_main_process:
            network = accelerator.unwrap_model(network)

        accelerator.end_training()
        optimizer_eval_fn()

        if is_main_process and (args.save_state or args.save_state_on_train_end):
            train_util.save_state_on_train_end(args, accelerator)

        if is_main_process:
            ckpt_name = train_util.get_last_ckpt_name(args, "." + args.save_model_as)
            save_model(ckpt_name, network, global_step, num_train_epochs, force_sync_upload=True)

            logger.info("model saved.")


def setup_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser()

    add_logging_arguments(parser)
    train_util.add_sd_models_arguments(parser)
    train_util.add_dataset_arguments(parser, True, True, True)
    train_util.add_training_arguments(parser, True)
    train_util.add_masked_loss_arguments(parser)
    deepspeed_utils.add_deepspeed_arguments(parser)
    train_util.add_optimizer_arguments(parser)
    config_util.add_config_arguments(parser)
    custom_train_functions.add_custom_train_arguments(parser)

    parser.add_argument(
        "--cpu_offload_checkpointing",
        action="store_true",
        help="[EXPERIMENTAL] enable offloading of tensors to CPU during checkpointing for U-Net or DiT, if supported"
        " / CPU）",
    )
    parser.add_argument(
        "--no_metadata", action="store_true", help="do not save metadata in output model / "
    )
    parser.add_argument(
        "--save_model_as",
        type=str,
        default="safetensors",
        choices=[None, "ckpt", "pt", "safetensors"],
        help="format to save the model (default is .safetensors)",
    )

    parser.add_argument("--unet_lr", type=float, default=None, help="learning rate for U-Net ")
    parser.add_argument(
        "--text_encoder_lr",
        type=float,
        default=None,
        nargs="*",
        help="learning rate for Text Encoder, can be multiple",
    )
    parser.add_argument(
        "--fp8_base_unet",
        action="store_true",
        help="use fp8 for U-Net (or DiT), Text Encoder is fp16 or bf16"
        " / ",
    )

    parser.add_argument(
        "--network_weights", type=str, default=None, help="pretrained weights for network"
    )
    parser.add_argument(
        "--network_module", type=str, default=None, help="network module to train "
    )
    parser.add_argument(
        "--network_dim",
        type=int,
        default=None,
        help="network dimensions (depends on each network) ",
    )
    parser.add_argument(
        "--network_alpha",
        type=float,
        default=1,
        help="alpha for LoRA weight scaling, default 1 (same as network_dim for same behavior as old version) ",
    )
    parser.add_argument(
        "--network_dropout",
        type=float,
        default=None,
        help="Drops neurons out of training every step (0 or None is default behavior (no dropout), 1 would drop all neurons) ",
    )
    parser.add_argument(
        "--network_args",
        type=str,
        default=None,
        nargs="*",
        help="additional arguments for network (key=value) ",
    )
    parser.add_argument(
        "--network_train_unet_only", action="store_true", help="only training U-Net part "
    )
    parser.add_argument(
        "--network_train_text_encoder_only",
        action="store_true",
        help="only training Text Encoder part ",
    )
    parser.add_argument(
        "--training_comment",
        type=str,
        default=None,
        help="arbitrary comment string stored in metadata ",
    )
    parser.add_argument(
        "--dim_from_weights",
        action="store_true",
        help="automatically determine dim (rank) from network_weights ",
    )
    parser.add_argument(
        "--scale_weight_norms",
        type=float,
        default=None,
        help="Scale the weight of each key pair to help prevent overtraing via exploding gradients. (1 is a good starting point) / ",
    )
    parser.add_argument(
        "--base_weights",
        type=str,
        default=None,
        nargs="*",
        help="network weights to merge into the model before training / ",
    )
    parser.add_argument(
        "--base_weights_multiplier",
        type=float,
        default=None,
        nargs="*",
        help="multiplier for network weights to merge into the model before training / ",
    )
    parser.add_argument(
        "--no_half_vae",
        action="store_true",
        help="do not use fp16/bf16 VAE in mixed precision (use float VAE) ",
    )
    parser.add_argument(
        "--skip_until_initial_step",
        action="store_true",
        help="skip training until initial_step is reached ",
    )
    parser.add_argument(
        "--initial_epoch",
        type=int,
        default=None,
        help="initial epoch number, 1 means first epoch (same as not specifying). NOTE: initial_epoch/step doesn't affect to lr scheduler. Which means lr scheduler will start from 0 without `--resume`."
        + " / ",
    )
    parser.add_argument(
        "--initial_step",
        type=int,
        default=None,
        help="initial step number including all epochs, 0 means first step (same as not specifying). overwrites initial_epoch."
        + " / ",
    )
    # parser.add_argument("--loraplus_lr_ratio", default=None, type=float, help="LoRA+ learning rate ratio")
    # parser.add_argument("--loraplus_unet_lr_ratio", default=None, type=float, help="LoRA+ UNet learning rate ratio")
    # parser.add_argument("--loraplus_text_encoder_lr_ratio", default=None, type=float, help="LoRA+ text encoder learning rate ratio")
    return parser


if __name__ == "__main__":
    parser = setup_parser()

    args = parser.parse_args()
    train_util.verify_command_line_training_args(args)
    args = train_util.read_config_from_file(args, parser)

    trainer = NetworkTrainer()
    trainer.train(args)