# Copyright (c) Meta Platforms, Inc. and affiliates. # All rights reserved. # # This source code is licensed under the BSD-style license found in the # LICENSE file in the root directory of this source tree. import sys import time from functools import partial from typing import Any, Dict, List, Optional, Union from warnings import warn import torch from omegaconf import DictConfig, ListConfig from torch import nn from torch.distributed import ( destroy_process_group, init_device_mesh, init_process_group, ) from torch.distributed._tensor import DTensor from torch.distributed.tensor.parallel import parallelize_module from torch.optim import Optimizer from torchdata.stateful_dataloader import StatefulDataLoader from torchdata.stateful_dataloader.sampler import StatefulDistributedSampler from torchtune import config, modules, training, utils from torchtune.config._utils import _get_component_from_path from torchtune.data import padded_collate_packed from torchtune.datasets import ConcatDataset from torchtune.recipe_interfaces import FTRecipeInterface from torchtune.training import DummyProfiler, PROFILER_KEY from torchtune.training.activations import apply_selective_activation_checkpointing from torchtune.training.checkpointing._checkpoint_client import ( CheckpointClient, TrainingProgress, ) from torchtune.training.lr_schedulers import get_lr from tqdm import tqdm log = utils.get_logger("DEBUG") class FullFinetuneRecipeDistributed(FTRecipeInterface): """ Full finetuning recipe for dense transformer-based LLMs such as Llama2. This recipe supports distributed training and can be run on a single node (1 to 8 GPUs). Features: - FSDP. Supported using PyTorch's FSDP APIs. CPU offload of parameters, gradients, and optimizer states is supported via ``fsdp_cpu_offload``. Resharding of parameters after the forward pass is done by default (corresponding to FULL_SHARD sharding strategy), but can be disabled by setting the config ``fsdp_reshard_after_forward`` to False (this corresponds to SHARD_GRAD_OP sharding strategy). DDP is currently not supported. Training on CPU is not supported. - Activation Checkpointing. This can be controlled using the ``enable_activation_checkpointing`` flag. Activation checkpointing helps reduce the memory footprint since we no longer keep activations in memory and instead recompute them during the backward pass. This is especially helpful for larger batch sizes when you're memory constrained. But these savings in memory come at the cost of training performance. In most cases training can slow-down quite a bit as a result of this activation recomputation. - Activation Offloading. This can be controlled using the ``enable_activation_offloading`` flag. Activation offloading is a technique similar to activations checkpointing that helps reduce the memory footprint to prevent OOMs on CUDA and enable bigger batches. Where activations checkpointing drops the activation in the forward to recompute it later in the backward, activations offloading will drop the activation in the forward to the CPU and bring it back during the backward pass. As always, there is a tradeoff--these savings in memory can come at the cost of training performance and CPU resources. To recover some runtime cost, we've added an option to enable offloading on a different stream to permit overlapping with the computation. This option is currently only available on PyTorch 2.5 or later and will be enabled by default if an acceptable torch version is found. Activation offloading can be used in conjunction with activation checkpointing. - Precision. Full fp32 and bf16 training are supported. Precision is controlled using the ``dtype`` flag. When ``dtype=bf16``, all activations, gradients and optimizer states are in bfloat16. In most cases this should halve the memory footprint of full precision (fp32) training, without loss in model quality (will depend on the model, training data and other settings). For GPUs which do not support bfloat16, we fall back to fp32. Mixed precision training and fp16 precision are currently not supported. - Gradient Accumulation. You can simulate larger batch sizes by accumulating gradients. This is controlled using the ``gradient_accumulation_steps`` flag. Total Batch Size = batch_size * number of GPUs * gradient accumulation steps. For example: with batch_size=1, nproc_per_node=2 and gradient_accumulation_steps=32 we get a total batch size of 64. Gradient accumulation is especially useful when you are memory constrained. In this case, accumulating gradients might give you better training speed than enabling activation checkpointing. - Checkpointing. Model weights are checkpointed both at the end of each epoch and at the end of training. Optimizer state and recipe state (seed, total_epochs, number of epochs run etc) are only saved at the end of a given epoch and used in case of resuming training. Resuming training is controlled by the ``resume_from_checkpoint`` flag. Mid-epoch checkpointing is currently not supported. For more details on the checkpointer, please take a look at our checkpointer deepdive (https://pytorch.org/torchtune/main/deep_dives/checkpointer.html). - Logging. Terminal, Disk, WandB and TensorBoard are all supported. - Gradient Clipping. Gradient clipping is supported using the ``clip_grad_norm`` flag. By default, ``clip_grad_norm`` is set to ``None``. If you only want to log the grad norm, you can set ``clip_grad_norm='inf'``. For a full list of example configs for this recipe, run ``tune ls`` on the command line. Each config has example commands for how to kick-off training. Args: cfg (DictConfig): OmegaConf object parsed from yaml file Raises: ValueError: If ``dtype`` is set to fp16. RuntimeError: If ``dtype`` is set to bf16 and the hardware does not support bf16. RuntimeError: If ``left_pad_sequence`` is set as the data collator. RuntimeError: If ``enable_activation_offloading`` is True and device is not CUDA. RuntimeError: If ``enable_activation_offloading`` is True and ``enable_activation_checkpointing`` is False. """ def __init__(self, cfg: DictConfig) -> None: device_type = cfg.device self._device = utils.get_device(device=device_type) self._dtype = training.get_dtype(cfg.dtype, device=self._device) if self._dtype == torch.float16: raise ValueError( "full fp16 training is not supported with this recipe. Please use bf16 or fp32 instead." ) # Set up the backend for distributed training (NCCL, GLOO, etc.) self._enable_async_checkpointing = cfg.get("enable_async_checkpointing", False) self.fsdp_cpu_offload = cfg.get("fsdp_cpu_offload", False) self.distributed_backend = training.get_distributed_backend( device_type, offload_ops_to_cpu=self.fsdp_cpu_offload or self._enable_async_checkpointing, ) init_process_group(self.distributed_backend) # Initialize distributed variables self.world_size, self.rank = utils.get_world_size_and_rank() self._is_rank_zero = self.rank == 0 self.tensor_parallel_plan = config.instantiate( cfg.get("tensor_parallel_plan", None) ) self.tensor_parallel_dim = cfg.get("tensor_parallel_dim", 1) if self.tensor_parallel_dim > 1 and self.tensor_parallel_plan is None: raise ValueError( "Tensor Parallel plan needs to be provided when tensor parallel is enabled." ) if self.world_size % self.tensor_parallel_dim != 0: raise ValueError( f"world_size {self.world_size} must be divisible by tensor_parallel_dim {self.tensor_parallel_dim}" ) if self.tensor_parallel_dim > 1 and cfg.optimizer.get("fused", False): raise ValueError( "Tensor parallelism is currently incompatible with fused optimizer." ) self.data_parallel_dim = self.world_size // self.tensor_parallel_dim # Logging attributes self._output_dir = cfg.output_dir self._log_every_n_steps = cfg.get("log_every_n_steps", 1) self._log_peak_memory_stats = cfg.get("log_peak_memory_stats", False) if self._log_peak_memory_stats and device_type != "cuda": log.info( "log_peak_memory_stats was set to True, however, training does not use cuda. Setting log_peak_memory_stats=False." ) self._log_peak_memory_stats = False # Training cfg self._resume_from_checkpoint = cfg.resume_from_checkpoint self._gradient_accumulation_steps = cfg.gradient_accumulation_steps self._optimizer_in_bwd = cfg.get("optimizer_in_bwd", False) self._clip_grad_norm = cfg.get("clip_grad_norm", None) self._checkpoint_client = CheckpointClient(cfg) # Optimizer in backward is not compatible with gradient accumulation or gradient clipping if self._optimizer_in_bwd: if self._clip_grad_norm is not None: raise RuntimeError( "Gradient clipping is not supported with optimizer in bwd." "Please set clip_grad_norm=None, or optimizer_in_bwd=False." ) if self._gradient_accumulation_steps > 1: raise RuntimeError( "Gradient accumulation is not supported with optimizer in bwd." "Please set gradient_accumulation_steps=1, or optimizer_in_bwd=False." ) # activation checkpointing/offloading self._enable_activation_checkpointing = cfg.get( "enable_activation_checkpointing", False ) self._enable_activation_offloading = cfg.get( "enable_activation_offloading", False ) if self._enable_activation_offloading: if device_type != "cuda": raise RuntimeError( "enable_activation_offloading should only be True when training on CUDA" ) if not self._enable_activation_checkpointing: raise RuntimeError( "enable_activation_offloading should only be True when enable_activation_checkpointing is True" ) elif ( self._enable_activation_checkpointing and cfg.checkpointer.model_type != "LLAMA3_VISION" ): utils.log_rank_zero( log, "Hint: enable_activation_checkpointing is True, but enable_activation_offloading isn't. " "Enabling activation offloading should reduce memory further.", ) # These are public properties which are updated by the checkpoint loader # when ``resume_from_checkpoint`` is `True` or validated in tests self.seed = training.set_seed( seed=cfg.seed, debug_mode=cfg.get("cudnn_deterministic_mode", None) ) self.epochs_run = 0 self.total_epochs = cfg.epochs self.max_steps_per_epoch = cfg.max_steps_per_epoch self.global_step = 0 def _update_recipe_state(self, ckpt_dict: Dict[str, Any]) -> None: """ Updates the recipe state from checkpoint. """ try: self.epochs_run = ckpt_dict[training.EPOCHS_KEY] # on mismatch, warn the user and prevent the override if self.seed != ckpt_dict[training.SEED_KEY]: warn( message=( "Config value for seed does not match the checkpoint value, " f"using the checkpoint value: {ckpt_dict[training.SEED_KEY]}" ) ) self.seed = ckpt_dict[training.SEED_KEY] if self.max_steps_per_epoch != ckpt_dict[training.MAX_STEPS_KEY]: warn( message=( "Config value for max_steps_per_epoch does not match the checkpoint value, " f"using the checkpoint value: {ckpt_dict[training.MAX_STEPS_KEY]}" ) ) self.max_steps_per_epoch = ckpt_dict[training.MAX_STEPS_KEY] # on mismatch, warn the user but allow the override if self.total_epochs != ckpt_dict[training.TOTAL_EPOCHS_KEY]: warn( message=( "Config value for total_epochs does not match the checkpoint value, " f"using the config value: {self.total_epochs}" ) ) except KeyError as e: raise KeyError( "Checkpoint does not contain the required keys needed for updating recipe state. " "Are you sure you passed in the right recipe checkpoint?" ) from e def setup(self, cfg: DictConfig) -> None: """ Setup the recipe. This includes training state (if resume_from_checkpoint is True), model, tokenizer, loss, optimizer, lr scheduler, sampler, and dataloader. """ if self.fsdp_cpu_offload: # Utilize all available CPU cores for intra-op parallelism. This provides ~2x # speed up when benchmarking fused AdamW on CPU training.set_torch_num_threads() if self._is_rank_zero: self._metric_logger = config.instantiate(cfg.metric_logger) # log config with parameter override self._metric_logger.log_config(cfg) # Load the base model checkpoint_dict = self._checkpoint_client.load_base_checkpoint() self._compile = cfg.get("compile", False) self._model = self._setup_model( cfg_model=cfg.model, enable_activation_checkpointing=self._enable_activation_checkpointing, enable_activation_offloading=self._enable_activation_offloading, custom_sharded_layers=cfg.get("custom_sharded_layers", None), fsdp_cpu_offload=self.fsdp_cpu_offload, reshard_after_forward=cfg.get("fsdp_reshard_after_forward", True), model_state_dict=checkpoint_dict[training.MODEL_KEY], ac_mode=cfg.get("ac_mode", None), ac_option=cfg.get("ac_option", None), ) self._tokenizer = config.instantiate(cfg.tokenizer) self._optimizer = self._setup_optimizer( cfg_optimizer=cfg.optimizer, optimizer_in_bwd=self._optimizer_in_bwd, opt_state_dict=( checkpoint_dict[training.OPT_KEY] if training.OPT_KEY in checkpoint_dict else None ), ) if self._resume_from_checkpoint: # If async checkpointing is enabled, intermediate checkpoints are saved asynchronously # using the DistributedCheckpointer. # Therefore the recipe needs to load the distributed checkpoint to restore the training # progress. if self._enable_async_checkpointing: try: checkpoint_dict = ( self._checkpoint_client.load_distributed_checkpoint( self._model, ( self._optim_ckpt_wrapper if self._optimizer_in_bwd else self._optimizer ), ) ) except Exception as e: log.warning( f"Failed to load distributed checkpoint: {e}. Training will start from the base checkpoint." ) # Update the recipe state from the checkpoint state dict. self._update_recipe_state(checkpoint_dict) # initialize loss self._loss_fn = config.instantiate(cfg.loss) if self._compile: training.compile_loss(self._loss_fn, verbose=self._is_rank_zero) if self._loss_fn.__class__.__name__ == "CEWithChunkedOutputLoss": # set num_output_chunks for model self._model.set_num_output_chunks(self._loss_fn.num_output_chunks) utils.log_rank_zero(log, "Loss is initialized.") # sampler and dataloader depend on the tokenizer and loss_fn and should be # setup after both of these are initialized collate_name = cfg.get("collate_fn", "torchtune.data.padded_collate_sft") self._dataloader = self._setup_data( cfg_dataset=cfg.dataset, shuffle=cfg.shuffle, batch_size=cfg.batch_size, collate_fn=collate_name, ) # Finally update the recipe state which can only be correctly set after all of the # other components have been initialized and updated. # # Number of training steps in each epoch depends on the number of batches produced # by the dataloader, the max_steps_per_epoch param set by the user and the # gradient_accumulation_steps param. This value is used for logging and tracking # training state. The computation should happen after the dataloader has been setup self._steps_per_epoch = ( len(self._dataloader) // self._gradient_accumulation_steps ) if ( self.max_steps_per_epoch is not None and self.max_steps_per_epoch < self._steps_per_epoch ): self._steps_per_epoch = self.max_steps_per_epoch self.global_step = self.epochs_run * self._steps_per_epoch # Setup lr scheduler self._lr_scheduler = self._setup_lr_scheduler( cfg_lr_scheduler=cfg.get("lr_scheduler", None), num_training_steps=self.total_epochs * self._steps_per_epoch, last_epoch=self.global_step - 1, ) # Set up profiler, returns DummyProfiler (nullcontext object with no-op `step` method) # if cfg is missing profiler key or if `cfg.profiler.enabled = False` self._profiler = self._setup_profiler(cfg.get(PROFILER_KEY, None)) # Used to ignore labels for loss computation self.ignore_labels_cache = torch.full( (cfg.batch_size, 1), self._loss_fn.ignore_index, device=self._device ) def _setup_lr_scheduler( self, cfg_lr_scheduler: Optional[DictConfig], num_training_steps: int, last_epoch: int, ) -> Optional[Optimizer]: """ Set up the learning rate scheduler based on the provided configuration. It supports both standard optimization and optimizer-in-backward cases. Args: cfg_lr_scheduler (Optional[DictConfig]): The learning rate scheduler configuration. num_training_steps (int): The total number of training steps. last_epoch (int): The index of the last epoch. Returns: lr_scheduler (Optional[Optimizer]): The learning rate scheduler. """ if cfg_lr_scheduler is None: if self._is_rank_zero: log.info( "No learning rate scheduler configured. Using constant learning rate." ) return None if self._optimizer_in_bwd: # Use the first optimizer from the wrapper to represent the learning rate optimizer = next(iter(self._optim_ckpt_wrapper.optim_map.values())) else: # Standard case: use the single optimizer optimizer = self._optimizer # Instantiate the learning rate scheduler lr_scheduler = config.instantiate( cfg_lr_scheduler, optimizer, num_training_steps=num_training_steps, last_epoch=last_epoch, ) if self._optimizer_in_bwd: # Modify the scheduler for optimizer_in_bwd case self._optim_ckpt_wrapper.set_lr_scheduler(lr_scheduler) if self._is_rank_zero: log.info("Learning rate scheduler is initialized.") return lr_scheduler def _setup_profiler( self, cfg_profiler: Optional[DictConfig] = None ) -> Union[torch.profiler.profile, DummyProfiler]: """ Parses the `profiler` section of top-level `cfg` and sets up profiler Args: cfg_profiler (Optional[DictConfig]): ``profiler`` section of the top-level ``cfg`` (the main config passed to `recipe.main`). Default None. Returns: profiler: Union[torch.profiler.profile, DummyProfiler] - DummyProfiler is a nullcontext with no-op methods for `start`, `stop`, and `step` that can be used in place of `torch.profiler.profile` if profiler is not enabled such that the instrumented training loop does not need to be changed profiling is disabled. The profiler config can be provided in configs under the `profiler` key with the following layout: .. code-block:: yaml profiler: enabled: bool #Output directory of trace artifacts output_dir: str #`torch.profiler.ProfilerActivity` types to trace cpu: bool cuda: bool #Trace options profile_memory: bool with_stack: bool record_shapes: bool with_flops: bool # `torch.profiler.schedule` options: # wait_steps -> wait, warmup_steps -> warmup, active_steps -> active, num_cycles -> repeat wait_steps: int warmup_steps: int active_steps: int num_cycles: int """ # Missing profiler section in config, assume disabled if cfg_profiler is None: cfg_profiler = DictConfig({"enabled": False}) # Check that component is included and set correctly if cfg_profiler.get("_component_", None) is None: cfg_profiler["_component_"] = "torchtune.training.setup_torch_profiler" else: assert ( cfg_profiler.get("_component_") == "torchtune.training.setup_torch_profiler" ), "Only torch profiler supported currently: component must be `torchtune.training.setup_torch_profiler`" profiler, profiler_cfg = config.instantiate(cfg_profiler) utils.log_rank_zero( log, f" Profiler config after instantiation: {profiler_cfg}" ) if self._is_rank_zero: self.profiler_profile_memory = profiler_cfg.get("profile_memory", False) if profiler_cfg["enabled"]: self.profiler_wait_steps = profiler_cfg["wait_steps"] self.profiler_warmup_steps = profiler_cfg["warmup_steps"] self.profiler_active_steps = profiler_cfg["active_steps"] return profiler def _setup_model( self, cfg_model: DictConfig, enable_activation_checkpointing: bool, enable_activation_offloading: bool, fsdp_cpu_offload: bool, reshard_after_forward: bool, model_state_dict: Dict[str, Any], custom_sharded_layers: Optional[List[str]] = None, ac_mode: Optional[str] = None, ac_option: Optional[int] = None, ) -> nn.Module: """ Model initialization has some important considerations: a. To minimize GPU peak memory, we initialize the model on meta device with the right dtype b. All ranks calls ``load_state_dict`` without peaking CPU RAMs since full state dicts are loaded with ``torch.load(mmap=True)`` """ utils.log_rank_zero( log, "Distributed training is enabled. Instantiating model and loading checkpoint on Rank 0 ...", ) init_start = time.perf_counter() with training.set_default_dtype(self._dtype), torch.device("meta"): model = config.instantiate(cfg_model) if self._compile: training.compile_model(model, verbose=self._is_rank_zero) device_mesh = init_device_mesh( self._device.type, mesh_shape=(self.data_parallel_dim, self.tensor_parallel_dim), mesh_dim_names=("dp", "tp"), ) self.dp_size = device_mesh["dp"].size() self.dp_rank = device_mesh["dp"].get_local_rank() # Apply tensor parallelism to the model if self.tensor_parallel_dim > 1: # Use the local number (num_heads, num_kv_heads, embed_dim) to account for tensor parallel model = training.prepare_mha_for_tp(model, device_mesh["tp"]) parallelize_module( model, device_mesh["tp"], parallelize_plan=self.tensor_parallel_plan, ) # We currently have two versions of activation checkpointing in this recipe # for testing and BC purposes. ``enable_activation_checkpointing`` controls # the older version of AC and this behavior is unchanged # ac_mode and ac_option together control selective AC. This is only enabled # when these are set AND ``enable_activation_checkpointing`` is set to False # We'll clean this up as soon as testing of AC is complete if (not enable_activation_checkpointing) and (ac_mode is not None): apply_selective_activation_checkpointing( model, ac_mode, ac_option, ) # original activation checkpointing (full) - flip the condition above if enable_activation_checkpointing and ac_mode is None: training.set_activation_checkpointing( model, auto_wrap_policy={modules.TransformerSelfAttentionLayer} ) # Apply Fully Sharded Data Parallelism to the model if self.data_parallel_dim > 1: fsdp_shard_conditions = [ partial( training.get_shard_conditions, names_to_match=custom_sharded_layers, ) ] training.shard_model( model=model, shard_conditions=fsdp_shard_conditions, cpu_offload=fsdp_cpu_offload, reshard_after_forward=reshard_after_forward, dp_mesh=device_mesh["dp"], ) with training.set_default_dtype(self._dtype), self._device: for m in model.modules(): # RoPE is not covered in state dict if hasattr(m, "rope_init"): m.rope_init() # This method will convert the full model state dict into a sharded state # dict and load into the model training.load_from_full_model_state_dict( model, model_state_dict, self._device, strict=True, cpu_offload=fsdp_cpu_offload, ) # activation offloading self.activations_handling_ctx = training.get_act_offloading_ctx_manager( model, enable_activation_offloading ) # Ensure no params and buffers are on meta device training.validate_no_params_on_meta_device(model) utils.log_rank_zero( log, f"Instantiating model and loading checkpoint took {time.perf_counter() - init_start:.2f} secs", ) if self._is_rank_zero: memory_stats = training.get_memory_stats(device=self._device) training.log_memory_stats(memory_stats) # synchronize before training begins torch.distributed.barrier() return model def _setup_optimizer( self, cfg_optimizer: DictConfig, optimizer_in_bwd: bool = False, opt_state_dict: Optional[Dict[str, Any]] = None, ) -> Optional[Optimizer]: if optimizer_in_bwd: # Maintain a dict of optims for every parameter. optim_dict = { param: config.instantiate(cfg_optimizer, [param]) for param in self._model.parameters() } # Register optimizer step hooks on the model to run optimizer in backward. training.register_optim_in_bwd_hooks( model=self._model, optim_dict=optim_dict ) # Create a wrapper for checkpoint save/load of optimizer states when running in backward. self._optim_ckpt_wrapper = training.create_optim_in_bwd_wrapper( model=self._model, optim_dict=optim_dict ) # Load optimizer states for each param. If optimizer states are being restored in an optimizer in # backward run, these need to have been saved with the same setting. Cannot restore from runs that # did not use optimizer in backward. if opt_state_dict is not None: for param in opt_state_dict.keys(): try: training.load_from_full_optimizer_state_dict( self._model, self._optim_ckpt_wrapper.optim_map[param], opt_state_dict[param], self._device, ) except BaseException as e: raise RuntimeError( "Failed loading in-backward optimizer checkpoints." "Please make sure run being restored from was using in-backward optimizer." ) from e utils.log_rank_zero(log, "In-backward optimizers are set up.") return None else: optimizer = config.instantiate(cfg_optimizer, self._model.parameters()) if opt_state_dict: training.load_from_full_optimizer_state_dict( self._model, optimizer, opt_state_dict, self._device, ) utils.log_rank_zero(log, "Optimizer is initialized.") return optimizer def _setup_data( self, cfg_dataset: DictConfig, shuffle: bool, batch_size: int, collate_fn: str, dataloader_state_dict: Optional[Dict[str, Any]] = None, ) -> StatefulDataLoader: """ All data related setup happens here. This recipe currently supports only map-style datasets. If a state_dict is provided (meaning we are resuming a training run), it is loaded into the dataloader. """ if isinstance(cfg_dataset, ListConfig): datasets = [ config.instantiate(single_cfg_dataset, self._tokenizer) for single_cfg_dataset in cfg_dataset ] ds = ConcatDataset(datasets=datasets) packed = getattr(ds, "packed", False) else: ds = config.instantiate(cfg_dataset, self._tokenizer) packed = cfg_dataset.get("packed", False) # Instantiate collate_fn if "left_pad_sequence" in collate_fn: raise RuntimeError("left_pad_sequence collator is only for inference.") collate_fn = _get_component_from_path(collate_fn) sampler = StatefulDistributedSampler( ds, num_replicas=self.dp_size, rank=self.dp_rank, shuffle=shuffle ) dataloader = StatefulDataLoader( dataset=ds, batch_size=batch_size, sampler=sampler, collate_fn=( partial( collate_fn, padding_idx=self._tokenizer.pad_id, ignore_idx=self._loss_fn.ignore_index, ) if not packed else padded_collate_packed ), # dropping last avoids shape issues with compile + flex attention drop_last=True, ) return dataloader def train(self) -> None: """ The core training loop. """ # clean up before training begins training.cleanup_before_training() # zero out the gradients before starting training if not self._optimizer_in_bwd: self._optimizer.zero_grad() else: for opt in self._optim_ckpt_wrapper.optim_map.values(): opt.zero_grad() # Initialize tokens count and running loss (for grad accumulation) t0 = time.perf_counter() running_loss = 0 num_tokens = 0 self._profiler.start() # self.epochs_run should be non-zero when we're resuming from a checkpoint for curr_epoch in range(self.epochs_run, self.total_epochs): pbar = tqdm(total=self._steps_per_epoch, disable=not self._is_rank_zero) self._dataloader.sampler.set_epoch(curr_epoch) for idx, batch in enumerate(self._dataloader): # Start tracking CUDA memory for active steps for just the first epoch if ( self._is_rank_zero and curr_epoch == 0 and self.profiler_profile_memory and idx == self.profiler_wait_steps + self.profiler_warmup_steps and self._device.type == "cuda" ): torch.cuda.memory._record_memory_history() utils.batch_to_device(batch, self._device) # Calculate the number of unmasked tokens in the current batch # and increment the total number of tokens seen in the step current_num_tokens = ( batch["labels"] != self._loss_fn.ignore_index ).sum() num_tokens += current_num_tokens # Shape [b, s], needed for the loss not the model labels = batch.pop("labels") with self.activations_handling_ctx: logits = self._model(**batch) # Shift labels to compute loss # equivalent to doing labels[..., 1:] and logits[..., :-1, :] # But this way we dont need to slice the logits. We just add an ignore index to labels. labels = torch.hstack( (labels[..., 1:], self.ignore_labels_cache[: labels.shape[0]]) ) if not isinstance(logits, list): labels = labels.reshape(-1) logits = logits.reshape(-1, logits.size(-1)) # Compute loss # Loss is normalized by default so we multiply by the number of tokens # This way we can normalize by the total number of tokens if we're accumulating gradients current_loss = self._loss_fn(logits, labels) * current_num_tokens # free logits otherwise it peaks backward memory del logits running_loss += current_loss # For optimizer in backward, we need to normalize before calling backward # This case and gradient accumulation are mutually exclusive if self._optimizer_in_bwd: torch.distributed.all_reduce(num_tokens) torch.distributed.all_reduce(running_loss) # We multiply by world_size to undo FSDP2 gradient normalization. current_loss = current_loss * (self.world_size / num_tokens) current_loss.backward() # Step with optimizer if (idx + 1) % self._gradient_accumulation_steps == 0: if not self._optimizer_in_bwd: # Get total number of tokens across all ranks to normalize gradients torch.distributed.all_reduce(num_tokens) # This will ensure that the logged loss matches what we're optimizing torch.distributed.all_reduce(running_loss) # Manually scale the gradients from unnormalized loss by total # of tokens # We multiply by world_size to undo FSDP2 gradient normalization. training.scale_grads(self._model, self.world_size / num_tokens) if self._clip_grad_norm is not None: grad_norm = torch.nn.utils.clip_grad_norm_( self._model.parameters(), max_norm=float(self._clip_grad_norm), ) # If sharded, collect the DTensor here if isinstance(grad_norm, DTensor): grad_norm = grad_norm.full_tensor() self._optimizer.step() self._optimizer.zero_grad(set_to_none=True) # Update the number of steps when the weights are updated self.global_step += 1 # Step the learning rate scheduler if self._lr_scheduler is not None: self._lr_scheduler.step() loss_to_log = running_loss.item() / num_tokens pbar.update(1) pbar.set_description( f"{curr_epoch + 1}|{self.global_step}|Loss: {loss_to_log}" ) # Log per-step metrics if ( self.global_step % self._log_every_n_steps == 0 and self._is_rank_zero ): time_per_step = time.perf_counter() - t0 log_dict = { "loss": loss_to_log, "lr": get_lr( ( self._optimizer if not self._optimizer_in_bwd else self._optim_ckpt_wrapper ), ), "tokens_per_second_per_gpu": num_tokens / (time_per_step * self.world_size), } if self._log_peak_memory_stats: log_dict.update( training.get_memory_stats(device=self._device) ) if self._clip_grad_norm is not None: log_dict.update({"grad_norm": grad_norm}) self._metric_logger.log_dict( log_dict, step=self.global_step, ) # Reset running stats for the next step running_loss = 0 num_tokens = 0 t0 = time.perf_counter() # Stop tracking CUDA memory now that active steps are complete if ( self._is_rank_zero and curr_epoch == 0 and self.profiler_profile_memory and idx == self.profiler_wait_steps + self.profiler_warmup_steps + self.profiler_active_steps and self._device.type == "cuda" ): torch.cuda.memory._record_memory_history(enabled=None) # Step profiler # Note that this is called within gradient accumulation block, hence # will include multiple forward / backward passes if gradient accumulation > 1 self._profiler.step() if ( (idx + 1) // self._gradient_accumulation_steps ) == self.max_steps_per_epoch: break self.epochs_run += 1 self._checkpoint_client.save_checkpoint( model=self._model, optimizer=( self._optimizer if not self._optimizer_in_bwd else self._optim_ckpt_wrapper ), training_progress=TrainingProgress( seed=self.seed, epochs_run=self.epochs_run, total_epochs=self.total_epochs, max_steps_per_epoch=self.max_steps_per_epoch, dataloader_state_dict=self._dataloader.state_dict(), ), epoch=curr_epoch, ) self._profiler.stop() def cleanup(self) -> None: if self._is_rank_zero: self._metric_logger.close() destroy_process_group() @config.parse def recipe_main(cfg: DictConfig) -> None: """ Entry point for the recipe. Configurable parameters are read in the following order: - Parameters specified in config (see available configs through ``tune ls``) - Overwritten by arguments from the command-line """ config.log_config(recipe_name="FullFinetuneRecipeDistributed", cfg=cfg) recipe = FullFinetuneRecipeDistributed(cfg=cfg) recipe.setup(cfg=cfg) recipe.train() recipe.cleanup() if __name__ == "__main__": sys.exit(recipe_main())