FineTrainers-Conditioning/finetrainers/trainer.py

import json
import logging
import math
import os
import random
from datetime import timedelta
from typing import Any, Dict
from pathlib import Path

import diffusers
import torch
import torch.backends
import transformers
import wandb
from accelerate import Accelerator, DistributedType
from accelerate.logging import get_logger
from accelerate.utils import (
    DistributedDataParallelKwargs,
    InitProcessGroupKwargs,
    ProjectConfiguration,
    set_seed,
    gather_object,
)
from diffusers.optimization import get_scheduler
from diffusers.training_utils import (
    cast_training_params,
    compute_density_for_timestep_sampling,
    compute_loss_weighting_for_sd3,
)
from diffusers.models.autoencoders.vae import DiagonalGaussianDistribution
from diffusers.utils import export_to_video, load_image, load_video
from huggingface_hub import create_repo, upload_folder
from peft import LoraConfig, get_peft_model_state_dict, set_peft_model_state_dict
from tqdm import tqdm

from .args import Args, validate_args, _INVERSE_DTYPE_MAP
from .constants import (
    FINETRAINERS_LOG_LEVEL,
    PRECOMPUTED_DIR_NAME,
    PRECOMPUTED_CONDITIONS_DIR_NAME,
    PRECOMPUTED_LATENTS_DIR_NAME,
)
from .dataset import BucketSampler, PrecomputedDataset, VideoDatasetWithResizing
from .models import get_config_from_model_name
from .state import State
from .utils.data_utils import should_perform_precomputation
from .utils.file_utils import string_to_filename
from .utils.optimizer_utils import get_optimizer
from .utils.memory_utils import get_memory_statistics, free_memory, make_contiguous
from .utils.torch_utils import unwrap_model, align_device_and_dtype, expand_tensor_to_dims
from .utils.checkpointing import get_latest_ckpt_path_to_resume_from, get_intermediate_ckpt_path


logger = get_logger("finetrainers")
logger.setLevel(FINETRAINERS_LOG_LEVEL)


class Trainer:
    def __init__(self, args: Args) -> None:
        validate_args(args)

        self.args = args
        self.state = State()

        # Tokenizers
        self.tokenizer = None
        self.tokenizer_2 = None
        self.tokenizer_3 = None

        # Text encoders
        self.text_encoder = None
        self.text_encoder_2 = None
        self.text_encoder_3 = None

        # Denoisers
        self.transformer = None
        self.unet = None

        # Autoencoders
        self.vae = None

        # Scheduler
        self.scheduler = None

        self._init_distributed()
        self._init_logging()
        self._init_directories_and_repositories()

        self.state.model_name = self.args.model_name
        self.model_config = get_config_from_model_name(self.args.model_name, self.args.training_type)

    def prepare_dataset(self) -> None:
        # TODO(aryan): Make a background process for fetching
        logger.info("Initializing dataset and dataloader")

        self.dataset = VideoDatasetWithResizing(
            data_root=self.args.data_root,
            caption_column=self.args.caption_column,
            video_column=self.args.video_column,
            resolution_buckets=self.args.video_resolution_buckets,
            dataset_file=self.args.dataset_file,
            id_token=self.args.id_token,
        )
        self.dataloader = torch.utils.data.DataLoader(
            self.dataset,
            batch_size=1,
            sampler=BucketSampler(self.dataset, batch_size=self.args.batch_size, shuffle=True),
            collate_fn=self.model_config.get("collate_fn"),
            num_workers=self.args.dataloader_num_workers,
            pin_memory=self.args.pin_memory,
        )

    def _get_load_components_kwargs(self) -> Dict[str, Any]:
        load_component_kwargs = {
            "text_encoder_dtype": self.args.text_encoder_dtype,
            "text_encoder_2_dtype": self.args.text_encoder_2_dtype,
            "text_encoder_3_dtype": self.args.text_encoder_3_dtype,
            "transformer_dtype": self.args.transformer_dtype,
            "vae_dtype": self.args.vae_dtype,
            "revision": self.args.revision,
            "cache_dir": self.args.cache_dir,
        }
        if self.args.pretrained_model_name_or_path is not None:
            load_component_kwargs["model_id"] = self.args.pretrained_model_name_or_path
        return load_component_kwargs

    def _set_components(self, components: Dict[str, Any]) -> None:
        self.tokenizer = components.get("tokenizer", self.tokenizer)
        self.tokenizer_2 = components.get("tokenizer_2", self.tokenizer_2)
        self.tokenizer_3 = components.get("tokenizer_3", self.tokenizer_3)
        self.text_encoder = components.get("text_encoder", self.text_encoder)
        self.text_encoder_2 = components.get("text_encoder_2", self.text_encoder_2)
        self.text_encoder_3 = components.get("text_encoder_3", self.text_encoder_3)
        self.transformer = components.get("transformer", self.transformer)
        self.unet = components.get("unet", self.unet)
        self.vae = components.get("vae", self.vae)
        self.scheduler = components.get("scheduler", self.scheduler)

    def _delete_components(self) -> None:
        self.tokenizer = None
        self.tokenizer_2 = None
        self.tokenizer_3 = None
        self.text_encoder = None
        self.text_encoder_2 = None
        self.text_encoder_3 = None
        self.transformer = None
        self.unet = None
        self.vae = None
        self.scheduler = None
        free_memory()
        torch.cuda.synchronize(self.state.accelerator.device)

    def prepare_models(self) -> None:
        logger.info("Initializing models")

        load_components_kwargs = self._get_load_components_kwargs()
        condition_components, latent_components, diffusion_components = {}, {}, {}
        if not self.args.precompute_conditions:
            condition_components = self.model_config["load_condition_models"](**load_components_kwargs)
            latent_components = self.model_config["load_latent_models"](**load_components_kwargs)
            diffusion_components = self.model_config["load_diffusion_models"](**load_components_kwargs)

        components = {}
        components.update(condition_components)
        components.update(latent_components)
        components.update(diffusion_components)
        self._set_components(components)

        if self.vae is not None:
            if self.args.enable_slicing:
                self.vae.enable_slicing()
            if self.args.enable_tiling:
                self.vae.enable_tiling()

        self.transformer_config = self.transformer.config if self.transformer is not None else None

    def prepare_precomputations(self) -> None:
        if not self.args.precompute_conditions:
            return

        logger.info("Initializing precomputations")

        if self.args.batch_size != 1:
            raise ValueError("Precomputation is only supported with batch size 1. This will be supported in future.")

        def collate_fn(batch):
            latent_conditions = [x["latent_conditions"] for x in batch]
            text_conditions = [x["text_conditions"] for x in batch]
            batched_latent_conditions = {}
            batched_text_conditions = {}
            for key in list(latent_conditions[0].keys()):
                if torch.is_tensor(latent_conditions[0][key]):
                    batched_latent_conditions[key] = torch.cat([x[key] for x in latent_conditions], dim=0)
                else:
                    # TODO(aryan): implement batch sampler for precomputed latents
                    batched_latent_conditions[key] = [x[key] for x in latent_conditions][0]
            for key in list(text_conditions[0].keys()):
                if torch.is_tensor(text_conditions[0][key]):
                    batched_text_conditions[key] = torch.cat([x[key] for x in text_conditions], dim=0)
                else:
                    # TODO(aryan): implement batch sampler for precomputed latents
                    batched_text_conditions[key] = [x[key] for x in text_conditions][0]
            return {"latent_conditions": batched_latent_conditions, "text_conditions": batched_text_conditions}

        should_precompute = should_perform_precomputation(self.args.data_root)
        if not should_precompute:
            logger.info("Precomputed conditions and latents found. Loading precomputed data.")
            self.dataloader = torch.utils.data.DataLoader(
                PrecomputedDataset(self.args.data_root),
                batch_size=self.args.batch_size,
                shuffle=True,
                collate_fn=collate_fn,
                num_workers=self.args.dataloader_num_workers,
                pin_memory=self.args.pin_memory,
            )
            return

        logger.info("Precomputed conditions and latents not found. Running precomputation.")

        # At this point, no models are loaded, so we need to load and precompute conditions and latents
        condition_components = self.model_config["load_condition_models"](**self._get_load_components_kwargs())
        self._set_components(condition_components)
        self._move_components_to_device()

        # TODO(aryan): refactor later. for now only lora is supported
        components_to_disable_grads = [
            self.text_encoder,
            self.text_encoder_2,
            self.text_encoder_3,
        ]
        for component in components_to_disable_grads:
            if component is not None:
                component.requires_grad_(False)

        if self.args.caption_dropout_p > 0 and self.args.caption_dropout_technique == "empty":
            logger.warning(
                "Caption dropout is not supported with precomputation yet. This will be supported in the future."
            )

        conditions_dir = Path(self.args.data_root) / PRECOMPUTED_DIR_NAME / PRECOMPUTED_CONDITIONS_DIR_NAME
        latents_dir = Path(self.args.data_root) / PRECOMPUTED_DIR_NAME / PRECOMPUTED_LATENTS_DIR_NAME
        conditions_dir.mkdir(parents=True, exist_ok=True)
        latents_dir.mkdir(parents=True, exist_ok=True)

        # Precompute conditions
        progress_bar = tqdm(
            range(0, len(self.dataset)),
            desc="Precomputing conditions",
            disable=not self.state.accelerator.is_local_main_process,
        )
        index = 0
        for i, data in enumerate(self.dataset):
            if i % self.state.accelerator.num_processes != self.state.accelerator.process_index:
                continue

            logger.debug(
                f"Precomputing conditions and latents for batch {i + 1}/{len(self.dataset)} on process {self.state.accelerator.process_index}"
            )

            text_conditions = self.model_config["prepare_conditions"](
                tokenizer=self.tokenizer,
                tokenizer_2=self.tokenizer_2,
                tokenizer_3=self.tokenizer_3,
                text_encoder=self.text_encoder,
                text_encoder_2=self.text_encoder_2,
                text_encoder_3=self.text_encoder_3,
                prompt=data["prompt"],
                device=self.state.accelerator.device,
                dtype=self.state.weight_dtype,
            )
            filename = conditions_dir / f"conditions-{i}-{index}.pt"
            torch.save(text_conditions, filename.as_posix())
            index += 1
            progress_bar.update(1)
        self._delete_components()

        memory_statistics = get_memory_statistics()
        logger.info(f"Memory after precomputing conditions: {json.dumps(memory_statistics, indent=4)}")
        torch.cuda.reset_peak_memory_stats(self.state.accelerator.device)

        # Precompute latents
        latent_components = self.model_config["load_latent_models"](**self._get_load_components_kwargs())
        self._set_components(latent_components)
        self._move_components_to_device()

        # TODO(aryan): refactor later
        components_to_disable_grads = [self.vae]
        for component in components_to_disable_grads:
            if component is not None:
                component.requires_grad_(False)

        if self.vae is not None:
            if self.args.enable_slicing:
                self.vae.enable_slicing()
            if self.args.enable_tiling:
                self.vae.enable_tiling()

        progress_bar = tqdm(
            range(0, len(self.dataset)),
            desc="Precomputing latents",
            disable=not self.state.accelerator.is_local_main_process,
        )
        index = 0
        for i, data in enumerate(self.dataset):
            if i % self.state.accelerator.num_processes != self.state.accelerator.process_index:
                continue

            logger.debug(
                f"Precomputing latents for batch {i + 1}/{len(self.dataset)} on process {self.state.accelerator.process_index}"
            )

            latent_conditions = self.model_config["prepare_latents"](
                vae=self.vae,
                image_or_video=data["video"].unsqueeze(0),
                device=self.state.accelerator.device,
                dtype=self.state.weight_dtype,
                generator=self.state.generator,
                precompute=True,
            )
            filename = latents_dir / f"latents-{self.state.accelerator.process_index}-{index}.pt"
            torch.save(latent_conditions, filename.as_posix())
            index += 1
            progress_bar.update(1)
        self._delete_components()

        self.state.accelerator.wait_for_everyone()
        logger.info("Precomputation complete")

        memory_statistics = get_memory_statistics()
        logger.info(f"Memory after precomputing latents: {json.dumps(memory_statistics, indent=4)}")
        torch.cuda.reset_peak_memory_stats(self.state.accelerator.device)

        # Update dataloader to use precomputed conditions and latents
        self.dataloader = torch.utils.data.DataLoader(
            PrecomputedDataset(self.args.data_root),
            batch_size=self.args.batch_size,
            shuffle=True,
            collate_fn=collate_fn,
            num_workers=self.args.dataloader_num_workers,
            pin_memory=self.args.pin_memory,
        )

    def prepare_trainable_parameters(self) -> None:
        logger.info("Initializing trainable parameters")

        diffusion_components = self.model_config["load_diffusion_models"](**self._get_load_components_kwargs())
        self._set_components(diffusion_components)

        # TODO(aryan): refactor later. for now only lora is supported
        components_to_disable_grads = [
            self.text_encoder,
            self.text_encoder_2,
            self.text_encoder_3,
            self.transformer,
            self.vae,
        ]
        for component in components_to_disable_grads:
            if component is not None:
                component.requires_grad_(False)

        # For mixed precision training we cast all non-trainable weights (vae, text_encoder and transformer) to half-precision
        # as these weights are only used for inference, keeping weights in full precision is not required.
        weight_dtype = self._get_training_dtype(accelerator=self.state.accelerator)

        if torch.backends.mps.is_available() and weight_dtype == torch.bfloat16:
            # due to pytorch#99272, MPS does not yet support bfloat16.
            raise ValueError(
                "Mixed precision training with bfloat16 is not supported on MPS. Please use fp16 (recommended) or fp32 instead."
            )

        # TODO(aryan): handle torch dtype from accelerator vs model dtype; refactor
        self.state.weight_dtype = weight_dtype
        if self.args.mixed_precision != _INVERSE_DTYPE_MAP[weight_dtype]:
            logger.warning(
                f"`mixed_precision` was set to {_INVERSE_DTYPE_MAP[weight_dtype]} which is different from configured argument ({self.args.mixed_precision})."
            )
        self.args.mixed_precision = _INVERSE_DTYPE_MAP[weight_dtype]
        self.transformer.to(dtype=weight_dtype)
        self._move_components_to_device()

        if self.args.gradient_checkpointing:
            self.transformer.enable_gradient_checkpointing()

        transformer_lora_config = LoraConfig(
            r=self.args.rank,
            lora_alpha=self.args.lora_alpha,
            init_lora_weights=True,
            target_modules=self.args.target_modules,
        )
        self.transformer.add_adapter(transformer_lora_config)

        # Enable TF32 for faster training on Ampere GPUs: https://pytorch.org/docs/stable/notes/cuda.html#tensorfloat-32-tf32-on-ampere-devices
        if self.args.allow_tf32 and torch.cuda.is_available():
            torch.backends.cuda.matmul.allow_tf32 = True

        self.register_saving_loading_hooks(transformer_lora_config)

    def register_saving_loading_hooks(self, transformer_lora_config):
        # create custom saving & loading hooks so that `accelerator.save_state(...)` serializes in a nice format
        def save_model_hook(models, weights, output_dir):
            if self.state.accelerator.is_main_process:
                transformer_lora_layers_to_save = None

                for model in models:
                    if isinstance(
                        unwrap_model(self.state.accelerator, model),
                        type(unwrap_model(self.state.accelerator, self.transformer)),
                    ):
                        model = unwrap_model(self.state.accelerator, model)
                        transformer_lora_layers_to_save = get_peft_model_state_dict(model)
                    else:
                        raise ValueError(f"Unexpected save model: {model.__class__}")

                    # make sure to pop weight so that corresponding model is not saved again
                    if weights:
                        weights.pop()

                self.model_config["pipeline_cls"].save_lora_weights(
                    output_dir,
                    transformer_lora_layers=transformer_lora_layers_to_save,
                )

        def load_model_hook(models, input_dir):
            if not self.state.accelerator.distributed_type == DistributedType.DEEPSPEED:
                while len(models) > 0:
                    model = models.pop()
                    if isinstance(
                        unwrap_model(self.state.accelerator, model),
                        type(unwrap_model(self.state.accelerator, self.transformer)),
                    ):
                        transformer_ = unwrap_model(self.state.accelerator, model)
                    else:
                        raise ValueError(
                            f"Unexpected save model: {unwrap_model(self.state.accelerator, model).__class__}"
                        )
            else:
                transformer_ = unwrap_model(self.state.accelerator, self.transformer).__class__.from_pretrained(
                    self.args.pretrained_model_name_or_path, subfolder="transformer"
                )
                transformer_.add_adapter(transformer_lora_config)

            lora_state_dict = self.model_config["pipeline_cls"].lora_state_dict(input_dir)
            transformer_state_dict = {
                f'{k.replace("transformer.", "")}': v
                for k, v in lora_state_dict.items()
                if k.startswith("transformer.")
            }
            incompatible_keys = set_peft_model_state_dict(transformer_, transformer_state_dict, adapter_name="default")
            if incompatible_keys is not None:
                # check only for unexpected keys
                unexpected_keys = getattr(incompatible_keys, "unexpected_keys", None)
                if unexpected_keys:
                    logger.warning(
                        f"Loading adapter weights from state_dict led to unexpected keys not found in the model: "
                        f" {unexpected_keys}. "
                    )

            # Make sure the trainable params are in float32. This is again needed since the base models
            # are in `weight_dtype`. More details:
            # https://github.com/huggingface/diffusers/pull/6514#discussion_r1449796804
            if self.args.mixed_precision == "fp16":
                # only upcast trainable parameters (LoRA) into fp32
                cast_training_params([transformer_])

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

    def prepare_optimizer(self) -> None:
        logger.info("Initializing optimizer and lr scheduler")

        self.state.train_epochs = self.args.train_epochs
        self.state.train_steps = self.args.train_steps

        # Make sure the trainable params are in float32
        if self.args.mixed_precision == "fp16":
            # only upcast trainable parameters (LoRA) into fp32
            cast_training_params([self.transformer], dtype=torch.float32)

        self.state.learning_rate = self.args.lr
        if self.args.scale_lr:
            self.state.learning_rate = (
                self.state.learning_rate
                * self.args.gradient_accumulation_steps
                * self.args.batch_size
                * self.state.accelerator.num_processes
            )

        transformer_lora_parameters = list(filter(lambda p: p.requires_grad, self.transformer.parameters()))
        transformer_parameters_with_lr = {
            "params": transformer_lora_parameters,
            "lr": self.state.learning_rate,
        }
        params_to_optimize = [transformer_parameters_with_lr]
        self.state.num_trainable_parameters = sum(p.numel() for p in transformer_lora_parameters)

        use_deepspeed_opt = (
            self.state.accelerator.state.deepspeed_plugin is not None
            and "optimizer" in self.state.accelerator.state.deepspeed_plugin.deepspeed_config
        )
        optimizer = get_optimizer(
            params_to_optimize=params_to_optimize,
            optimizer_name=self.args.optimizer,
            learning_rate=self.state.learning_rate,
            beta1=self.args.beta1,
            beta2=self.args.beta2,
            beta3=self.args.beta3,
            epsilon=self.args.epsilon,
            weight_decay=self.args.weight_decay,
            use_8bit=self.args.use_8bit_bnb,
            use_deepspeed=use_deepspeed_opt,
        )

        num_update_steps_per_epoch = math.ceil(len(self.dataloader) / self.args.gradient_accumulation_steps)
        if self.state.train_steps is None:
            self.state.train_steps = self.state.train_epochs * num_update_steps_per_epoch
            self.state.overwrote_max_train_steps = True

        use_deepspeed_lr_scheduler = (
            self.state.accelerator.state.deepspeed_plugin is not None
            and "scheduler" in self.state.accelerator.state.deepspeed_plugin.deepspeed_config
        )
        total_training_steps = self.state.train_steps * self.state.accelerator.num_processes
        num_warmup_steps = self.args.lr_warmup_steps * self.state.accelerator.num_processes

        if use_deepspeed_lr_scheduler:
            from accelerate.utils import DummyScheduler

            lr_scheduler = DummyScheduler(
                name=self.args.lr_scheduler,
                optimizer=optimizer,
                total_num_steps=total_training_steps,
                num_warmup_steps=num_warmup_steps,
            )
        else:
            lr_scheduler = get_scheduler(
                name=self.args.lr_scheduler,
                optimizer=optimizer,
                num_warmup_steps=num_warmup_steps,
                num_training_steps=total_training_steps,
                num_cycles=self.args.lr_num_cycles,
                power=self.args.lr_power,
            )

        self.optimizer = optimizer
        self.lr_scheduler = lr_scheduler

    def prepare_for_training(self) -> None:
        self.transformer, self.optimizer, self.dataloader, self.lr_scheduler = self.state.accelerator.prepare(
            self.transformer, self.optimizer, self.dataloader, self.lr_scheduler
        )

        # We need to recalculate our total training steps as the size of the training dataloader may have changed.
        num_update_steps_per_epoch = math.ceil(len(self.dataloader) / self.args.gradient_accumulation_steps)
        if self.state.overwrote_max_train_steps:
            self.state.train_steps = self.state.train_epochs * num_update_steps_per_epoch
        # Afterwards we recalculate our number of training epochs
        self.state.train_epochs = math.ceil(self.state.train_steps / num_update_steps_per_epoch)
        self.state.num_update_steps_per_epoch = num_update_steps_per_epoch

    def prepare_trackers(self) -> None:
        logger.info("Initializing trackers")

        tracker_name = self.args.tracker_name or "finetrainers-experiment"
        self.state.accelerator.init_trackers(tracker_name, config=self.args.to_dict())

    def train(self) -> None:
        logger.info("Starting training")

        memory_statistics = get_memory_statistics()
        logger.info(f"Memory before training start: {json.dumps(memory_statistics, indent=4)}")

        self.state.train_batch_size = (
            self.args.batch_size * self.state.accelerator.num_processes * self.args.gradient_accumulation_steps
        )
        info = {
            "trainable parameters": self.state.num_trainable_parameters,
            "total samples": len(self.dataset),
            "train epochs": self.state.train_epochs,
            "train steps": self.state.train_steps,
            "batches per device": self.args.batch_size,
            "total batches observed per epoch": len(self.dataloader),
            "train batch size": self.state.train_batch_size,
            "gradient accumulation steps": self.args.gradient_accumulation_steps,
        }
        logger.info(f"Training configuration: {json.dumps(info, indent=4)}")

        global_step = 0
        first_epoch = 0
        initial_global_step = 0

        # Potentially load in the weights and states from a previous save
        (
            resume_from_checkpoint_path,
            initial_global_step,
            global_step,
            first_epoch,
        ) = get_latest_ckpt_path_to_resume_from(
            resume_from_checkpoint=self.args.resume_from_checkpoint,
            num_update_steps_per_epoch=self.state.num_update_steps_per_epoch,
            output_dir=self.args.output_dir,
        )
        if resume_from_checkpoint_path:
            self.state.accelerator.load_state(resume_from_checkpoint_path)

        progress_bar = tqdm(
            range(0, self.state.train_steps),
            initial=initial_global_step,
            desc="Training steps",
            disable=not self.state.accelerator.is_local_main_process,
        )

        accelerator = self.state.accelerator
        weight_dtype = self.state.weight_dtype
        scheduler_sigmas = self.scheduler.sigmas.clone().to(device=accelerator.device, dtype=weight_dtype)
        generator = torch.Generator(device=accelerator.device)
        if self.args.seed is not None:
            generator = generator.manual_seed(self.args.seed)
        self.state.generator = generator

        for epoch in range(first_epoch, self.state.train_epochs):
            logger.debug(f"Starting epoch ({epoch + 1}/{self.state.train_epochs})")

            self.transformer.train()
            models_to_accumulate = [self.transformer]

            for step, batch in enumerate(self.dataloader):
                logger.debug(f"Starting step {step + 1}")
                logs = {}

                with accelerator.accumulate(models_to_accumulate):
                    if not self.args.precompute_conditions:
                        videos = batch["videos"]
                        prompts = batch["prompts"]
                        batch_size = len(prompts)

                        if self.args.caption_dropout_technique == "empty":
                            if random.random() < self.args.caption_dropout_p:
                                prompts = [""] * batch_size

                        latent_conditions = self.model_config["prepare_latents"](
                            vae=self.vae,
                            image_or_video=videos,
                            patch_size=self.transformer_config.patch_size,
                            patch_size_t=self.transformer_config.patch_size_t,
                            device=accelerator.device,
                            dtype=weight_dtype,
                            generator=generator,
                        )
                        text_conditions = self.model_config["prepare_conditions"](
                            tokenizer=self.tokenizer,
                            text_encoder=self.text_encoder,
                            tokenizer_2=self.tokenizer_2,
                            text_encoder_2=self.text_encoder_2,
                            prompt=prompts,
                            device=accelerator.device,
                            dtype=weight_dtype,
                        )
                    else:
                        latent_conditions = batch["latent_conditions"]
                        text_conditions = batch["text_conditions"]
                        latent_conditions["latents"] = DiagonalGaussianDistribution(
                            latent_conditions["latents"]
                        ).sample(generator)
                        if "post_latent_preparation" in self.model_config.keys():
                            latent_conditions = self.model_config["post_latent_preparation"](**latent_conditions)
                        align_device_and_dtype(latent_conditions, accelerator.device, weight_dtype)
                        align_device_and_dtype(text_conditions, accelerator.device, weight_dtype)
                        batch_size = latent_conditions["latents"].shape[0]

                    latent_conditions = make_contiguous(latent_conditions)
                    text_conditions = make_contiguous(text_conditions)

                    if self.args.caption_dropout_technique == "zero":
                        if random.random() < self.args.caption_dropout_p:
                            text_conditions["prompt_embeds"].fill_(0)
                            text_conditions["prompt_attention_mask"].fill_(False)

                            # TODO(aryan): refactor later
                            if "pooled_prompt_embeds" in text_conditions:
                                text_conditions["pooled_prompt_embeds"].fill_(0)

                    # These weighting schemes use a uniform timestep sampling and instead post-weight the loss
                    weights = compute_density_for_timestep_sampling(
                        weighting_scheme=self.args.flow_weighting_scheme,
                        batch_size=batch_size,
                        logit_mean=self.args.flow_logit_mean,
                        logit_std=self.args.flow_logit_std,
                        mode_scale=self.args.flow_mode_scale,
                    )
                    indices = (weights * self.scheduler.config.num_train_timesteps).long()
                    sigmas = scheduler_sigmas[indices]
                    timesteps = (sigmas * 1000.0).long()

                    noise = torch.randn(
                        latent_conditions["latents"].shape,
                        generator=generator,
                        device=accelerator.device,
                        dtype=weight_dtype,
                    )
                    sigmas = expand_tensor_to_dims(sigmas, ndim=latent_conditions["latents"].ndim)
                    noisy_latents = (1.0 - sigmas) * latent_conditions["latents"] + sigmas * noise

                    latent_conditions.update({"noisy_latents": noisy_latents})

                    # These weighting schemes use a uniform timestep sampling and instead post-weight the loss
                    weights = compute_loss_weighting_for_sd3(
                        weighting_scheme=self.args.flow_weighting_scheme, sigmas=sigmas
                    )
                    pred = self.model_config["forward_pass"](
                        transformer=self.transformer, timesteps=timesteps, **latent_conditions, **text_conditions
                    )
                    target = noise - latent_conditions["latents"]

                    loss = weights.float() * (pred["latents"].float() - target.float()).pow(2)
                    # Average loss across channel dimension
                    loss = loss.mean(list(range(1, loss.ndim)))
                    # Average loss across batch dimension
                    loss = loss.mean()
                    accelerator.backward(loss)

                    if accelerator.sync_gradients:
                        if accelerator.distributed_type == DistributedType.DEEPSPEED:
                            grad_norm = self.transformer.get_global_grad_norm()
                            # In some cases the grad norm may not return a float
                            if torch.is_tensor(grad_norm):
                                grad_norm = grad_norm.item()
                        else:
                            grad_norm = accelerator.clip_grad_norm_(
                                self.transformer.parameters(), self.args.max_grad_norm
                            )
                            if torch.is_tensor(grad_norm):
                                grad_norm = grad_norm.item()

                        logs["grad_norm"] = grad_norm

                    self.optimizer.step()
                    self.lr_scheduler.step()
                    self.optimizer.zero_grad()

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

                    # Checkpointing
                    if accelerator.distributed_type == DistributedType.DEEPSPEED or accelerator.is_main_process:
                        if global_step % self.args.checkpointing_steps == 0:
                            save_path = get_intermediate_ckpt_path(
                                checkpointing_limit=self.args.checkpointing_limit,
                                step=global_step,
                                output_dir=self.args.output_dir,
                            )
                            accelerator.save_state(save_path)

                # Maybe run validation
                should_run_validation = (
                    self.args.validation_every_n_steps is not None
                    and global_step % self.args.validation_every_n_steps == 0
                )
                if should_run_validation:
                    self.validate(global_step)

                logs["loss"] = loss.detach().item()
                logs["lr"] = self.lr_scheduler.get_last_lr()[0]
                progress_bar.set_postfix(logs)
                accelerator.log(logs, step=global_step)

                if global_step >= self.state.train_steps:
                    break

            memory_statistics = get_memory_statistics()
            logger.info(f"Memory after epoch {epoch + 1}: {json.dumps(memory_statistics, indent=4)}")

            # Maybe run validation
            should_run_validation = (
                self.args.validation_every_n_epochs is not None
                and (epoch + 1) % self.args.validation_every_n_epochs == 0
            )
            if should_run_validation:
                self.validate(global_step)

        accelerator.wait_for_everyone()
        if accelerator.is_main_process:
            # TODO: consider factoring this out when supporting other types of training algos.
            self.transformer = unwrap_model(accelerator, self.transformer)
            transformer_lora_layers = get_peft_model_state_dict(self.transformer)

            self.model_config["pipeline_cls"].save_lora_weights(
                save_directory=self.args.output_dir,
                transformer_lora_layers=transformer_lora_layers,
            )

        self.validate(step=global_step, final_validation=True)

        if accelerator.is_main_process:
            if self.args.push_to_hub:
                upload_folder(
                    repo_id=self.state.repo_id, folder_path=self.args.output_dir, ignore_patterns=["checkpoint-*"]
                )

        del self.tokenizer, self.text_encoder, self.transformer, self.vae, self.scheduler
        free_memory()
        memory_statistics = get_memory_statistics()
        logger.info(f"Memory after training end: {json.dumps(memory_statistics, indent=4)}")

        accelerator.end_training()

    def validate(self, step: int, final_validation: bool = False) -> None:
        logger.info("Starting validation")

        accelerator = self.state.accelerator
        num_validation_samples = len(self.args.validation_prompts)

        if num_validation_samples == 0:
            logger.warning("No validation samples found. Skipping validation.")
            return

        self.transformer.eval()

        memory_statistics = get_memory_statistics()
        logger.info(f"Memory before validation start: {json.dumps(memory_statistics, indent=4)}")

        if not final_validation:
            pipeline = self.model_config["initialize_pipeline"](
                model_id=self.args.pretrained_model_name_or_path,
                tokenizer=self.tokenizer,
                text_encoder=self.text_encoder,
                tokenizer_2=self.tokenizer_2,
                text_encoder_2=self.text_encoder_2,
                transformer=unwrap_model(accelerator, self.transformer),
                vae=self.vae,
                device=accelerator.device,
                revision=self.args.revision,
                cache_dir=self.args.cache_dir,
                enable_slicing=self.args.enable_slicing,
                enable_tiling=self.args.enable_tiling,
                enable_model_cpu_offload=self.args.enable_model_cpu_offload,
            )
        else:
            # `torch_dtype` is manually set within `initialize_pipeline()`.
            self._delete_components()
            pipeline = self.model_config["initialize_pipeline"](
                model_id=self.args.pretrained_model_name_or_path,
                device=accelerator.device,
                revision=self.args.revision,
                cache_dir=self.args.cache_dir,
                enable_slicing=self.args.enable_slicing,
                enable_tiling=self.args.enable_tiling,
                enable_model_cpu_offload=self.args.enable_model_cpu_offload,
            )
            pipeline.load_lora_weights(self.args.output_dir)

        all_processes_artifacts = []
        for i in range(num_validation_samples):
            # Skip current validation on all processes but one
            if i % accelerator.num_processes != accelerator.process_index:
                continue

            prompt = self.args.validation_prompts[i]
            image = self.args.validation_images[i]
            video = self.args.validation_videos[i]
            height = self.args.validation_heights[i]
            width = self.args.validation_widths[i]
            num_frames = self.args.validation_num_frames[i]

            if image is not None:
                image = load_image(image)
            if video is not None:
                video = load_video(video)

            logger.debug(
                f"Validating sample {i + 1}/{num_validation_samples} on process {accelerator.process_index}. Prompt: {prompt}",
                main_process_only=False,
            )
            validation_artifacts = self.model_config["validation"](
                pipeline=pipeline,
                prompt=prompt,
                image=image,
                video=video,
                height=height,
                width=width,
                num_frames=num_frames,
                num_videos_per_prompt=self.args.num_validation_videos_per_prompt,
                generator=self.state.generator,
                # todo support passing `fps` for supported pipelines.
            )

            prompt_filename = string_to_filename(prompt)[:25]
            artifacts = {
                "image": {"type": "image", "value": image},
                "video": {"type": "video", "value": video},
            }
            for i, (artifact_type, artifact_value) in enumerate(validation_artifacts):
                artifacts.update({f"artifact_{i}": {"type": artifact_type, "value": artifact_value}})
            logger.debug(
                f"Validation artifacts on process {accelerator.process_index}: {list(artifacts.keys())}",
                main_process_only=False,
            )

            for key, value in list(artifacts.items()):
                artifact_type = value["type"]
                artifact_value = value["value"]
                if artifact_type not in ["image", "video"] or artifact_value is None:
                    continue

                extension = "png" if artifact_type == "image" else "mp4"
                filename = f"validation-{step}-{accelerator.process_index}-{prompt_filename}.{extension}"
                filename = os.path.join(self.args.output_dir, filename)

                if artifact_type == "image":
                    logger.debug(f"Saving image to {filename}")
                    artifact_value.save(filename)
                    artifact_value = wandb.Image(filename)
                elif artifact_type == "video":
                    logger.debug(f"Saving video to {filename}")
                    # TODO: this should be configurable here as well as in validation runs where we call the pipeline that has `fps`.
                    export_to_video(artifact_value, filename, fps=15)
                    artifact_value = wandb.Video(filename, caption=prompt)

                all_processes_artifacts.append(artifact_value)

        all_artifacts = gather_object(all_processes_artifacts)

        if accelerator.is_main_process:
            tracker_key = "final" if final_validation else "validation"
            for tracker in accelerator.trackers:
                if tracker.name == "wandb":
                    image_artifacts = [artifact for artifact in all_artifacts if isinstance(artifact, wandb.Image)]
                    video_artifacts = [artifact for artifact in all_artifacts if isinstance(artifact, wandb.Video)]
                    tracker.log(
                        {
                            tracker_key: {"images": image_artifacts, "videos": video_artifacts},
                        },
                        step=step,
                    )


        # Remove all hooks that might have been added during pipeline initialization to the models
        pipeline.remove_all_hooks()
        del pipeline

        accelerator.wait_for_everyone()

        free_memory()
        memory_statistics = get_memory_statistics()
        logger.info(f"Memory after validation end: {json.dumps(memory_statistics, indent=4)}")
        torch.cuda.reset_peak_memory_stats(accelerator.device)

        if not final_validation:
            self.transformer.train()

    def evaluate(self) -> None:
        raise NotImplementedError

    def _init_distributed(self) -> None:
        logging_dir = Path(self.args.output_dir, self.args.logging_dir)
        project_config = ProjectConfiguration(project_dir=self.args.output_dir, logging_dir=logging_dir)
        ddp_kwargs = DistributedDataParallelKwargs(find_unused_parameters=True)
        init_process_group_kwargs = InitProcessGroupKwargs(
            backend="nccl", timeout=timedelta(seconds=self.args.nccl_timeout)
        )
        mixed_precision = "no" if torch.backends.mps.is_available() else self.args.mixed_precision
        report_to = None if self.args.report_to.lower() == "none" else self.args.report_to

        accelerator = Accelerator(
            project_config=project_config,
            gradient_accumulation_steps=self.args.gradient_accumulation_steps,
            mixed_precision=mixed_precision,
            log_with=report_to,
            kwargs_handlers=[ddp_kwargs, init_process_group_kwargs],
        )

        # Disable AMP for MPS.
        if torch.backends.mps.is_available():
            accelerator.native_amp = False

        self.state.accelerator = accelerator

        if self.args.seed is not None:
            self.state.seed = self.args.seed
            set_seed(self.args.seed)

    def _init_logging(self) -> None:
        logging.basicConfig(
            format="%(asctime)s - %(levelname)s - %(name)s - %(message)s",
            datefmt="%m/%d/%Y %H:%M:%S",
            level=FINETRAINERS_LOG_LEVEL,
        )
        if self.state.accelerator.is_local_main_process:
            transformers.utils.logging.set_verbosity_warning()
            diffusers.utils.logging.set_verbosity_info()
        else:
            transformers.utils.logging.set_verbosity_error()
            diffusers.utils.logging.set_verbosity_error()

        logger.info("Initialized FineTrainers")
        logger.info(self.state.accelerator.state, main_process_only=False)

    def _init_directories_and_repositories(self) -> None:
        if self.state.accelerator.is_main_process:
            self.args.output_dir = Path(self.args.output_dir)
            self.args.output_dir.mkdir(parents=True, exist_ok=True)
            self.state.output_dir = self.args.output_dir

            if self.args.push_to_hub:
                repo_id = self.args.hub_model_id or Path(self.args.output_dir).name
                self.state.repo_id = create_repo(token=self.args.hub_token, repo_id=repo_id, exist_ok=True).repo_id

    def _move_components_to_device(self):
        if self.text_encoder is not None:
            self.text_encoder = self.text_encoder.to(self.state.accelerator.device)
        if self.text_encoder_2 is not None:
            self.text_encoder_2 = self.text_encoder_2.to(self.state.accelerator.device)
        if self.text_encoder_3 is not None:
            self.text_encoder_3 = self.text_encoder_3.to(self.state.accelerator.device)
        if self.transformer is not None:
            self.transformer = self.transformer.to(self.state.accelerator.device)
        if self.unet is not None:
            self.unet = self.unet.to(self.state.accelerator.device)
        if self.vae is not None:
            self.vae = self.vae.to(self.state.accelerator.device)

    def _get_training_dtype(self, accelerator) -> torch.dtype:
        weight_dtype = torch.float32
        if accelerator.state.deepspeed_plugin:
            # DeepSpeed is handling precision, use what's in the DeepSpeed config
            if (
                "fp16" in accelerator.state.deepspeed_plugin.deepspeed_config
                and accelerator.state.deepspeed_plugin.deepspeed_config["fp16"]["enabled"]
            ):
                weight_dtype = torch.float16
            if (
                "bf16" in accelerator.state.deepspeed_plugin.deepspeed_config
                and accelerator.state.deepspeed_plugin.deepspeed_config["bf16"]["enabled"]
            ):
                weight_dtype = torch.bfloat16
        else:
            if self.state.accelerator.mixed_precision == "fp16":
                weight_dtype = torch.float16
            elif self.state.accelerator.mixed_precision == "bf16":
                weight_dtype = torch.bfloat16
        return weight_dtype