""" KTO trainer """ import os from typing import Any, Optional import torch import torch.distributed from coati.models.loss import KTOLoss from coati.models.utils import calc_masked_log_probs from coati.trainer.utils import all_reduce_mean from coati.utils import AccumulativeMeanMeter, save_checkpoint from torch.optim import Optimizer from torch.optim.lr_scheduler import _LRScheduler from torch.utils.data import DataLoader from tqdm import trange from transformers import PreTrainedTokenizerBase from colossalai.booster import Booster from colossalai.cluster import DistCoordinator from colossalai.utils import get_current_device from .base import SLTrainer from .utils import is_rank_0, to_device class KTOTrainer(SLTrainer): """ Trainer for KTO algorithm. Args: actor (Actor): the actor model in ppo algorithm ref_model (Critic): the reference model in ppo algorithm booster (Strategy): the strategy to use for training actor_optim (Optimizer): the optimizer to use for actor model actor_lr_scheduler (_LRScheduler): the lr scheduler to use for actor model tokenizer (PreTrainedTokenizerBase): the tokenizer to use for encoding max_epochs (int, defaults to 1): the max number of epochs to train accumulation_steps (int): the number of steps to accumulate gradients start_epoch (int, defaults to 0): the start epoch, non-zero if resumed from a checkpoint save_interval (int): the interval to save model checkpoints, default to 0, which means no checkpoint will be saved during trainning save_dir (str): the directory to save checkpoints coordinator (DistCoordinator): the coordinator to use for distributed logging beta (float, defaults to 0.1): the beta parameter in kto loss desirable_weight (float, defaults to 1.0): the weight for desirable reward undesirable_weight (float, defaults to 1.0): the weight for undesirable reward """ def __init__( self, actor: Any, ref_model: Any, booster: Booster, actor_optim: Optimizer, actor_lr_scheduler: _LRScheduler, tokenizer: PreTrainedTokenizerBase, max_epochs: int = 1, beta: float = 0.1, desirable_weight: float = 1.0, undesirable_weight: float = 1.0, accumulation_steps: int = 1, start_epoch: int = 0, save_interval: int = 0, save_dir: str = None, coordinator: DistCoordinator = None, ) -> None: super().__init__(booster, max_epochs=max_epochs, model=actor, optimizer=actor_optim, start_epoch=start_epoch) self.ref_model = ref_model self.actor_scheduler = actor_lr_scheduler self.tokenizer = tokenizer self.kto_loss = KTOLoss(beta=beta, desirable_weight=desirable_weight, undesirable_weight=undesirable_weight) self.save_interval = save_interval self.coordinator = coordinator self.save_dir = save_dir self.num_train_step = 0 self.accumulation_steps = accumulation_steps self.device = get_current_device() self.accumulative_meter = AccumulativeMeanMeter() self.desirable_weight = desirable_weight self.undesirable_weight = undesirable_weight self.beta = beta def _before_fit( self, train_preference_dataloader: DataLoader = None, eval_preference_dataloader: DataLoader = None, log_dir: Optional[str] = None, use_wandb: bool = False, ): """ Args: prompt_dataloader (DataLoader): the dataloader to use for prompt data pretrain_dataloader (DataLoader): the dataloader to use for pretrain data """ self.train_dataloader = train_preference_dataloader self.eval_dataloader = eval_preference_dataloader self.writer = None if use_wandb and is_rank_0(): assert log_dir is not None, "log_dir must be provided when use_wandb is True" import wandb self.wandb_run = wandb.init(project="Coati-kto", sync_tensorboard=True) if log_dir is not None and is_rank_0(): import os import time from torch.utils.tensorboard import SummaryWriter log_dir = os.path.join(log_dir, "kto") log_dir = os.path.join(log_dir, time.strftime("%Y-%m-%d_%H:%M:%S", time.localtime())) self.writer = SummaryWriter(log_dir=log_dir) def _train(self, epoch: int): """ Args: epoch int: the number of current epoch """ self.model.train() self.accumulative_meter.reset() step_bar = trange( len(self.train_dataloader) // self.accumulation_steps, desc=f"Epoch {epoch + 1}/{self.max_epochs}", disable=not is_rank_0(), ) for i, batch in enumerate(self.train_dataloader): batch = to_device(batch, self.device) (input_ids, attention_mask, loss_mask, label, kl_input_ids, kl_attention_mask, kl_loss_mask) = ( batch["input_ids"], batch["attention_mask"], batch["loss_mask"], batch["label"], batch["kl_input_ids"], batch["kl_attention_mask"], batch["kl_loss_mask"], ) batch_size = input_ids.size()[0] # actor logits with torch.no_grad(): # calculate KL term with KT data kl_logits = self.model( input_ids=kl_input_ids, attention_mask=kl_attention_mask, )["logits"] logits = self.model( input_ids=input_ids, attention_mask=attention_mask, )["logits"] logprob = calc_masked_log_probs(logits, input_ids, loss_mask[:, 1:]).sum(-1) kl_logprob = calc_masked_log_probs(kl_logits, kl_input_ids, kl_loss_mask[:, 1:]).sum(-1) chosen_index = [i for i in range(batch_size) if label[i] == 1] rejected_index = [i for i in range(batch_size) if label[i] == 0] chosen_logprob = logprob[chosen_index] rejected_logprob = logprob[rejected_index] with torch.no_grad(): ref_kl_logits = self.ref_model( input_ids=kl_input_ids, attention_mask=kl_attention_mask, )["logits"] ref_logits = self.ref_model( input_ids=input_ids, attention_mask=attention_mask, )["logits"] ref_logprob = calc_masked_log_probs(ref_logits, input_ids, loss_mask[:, 1:]).sum(-1) ref_kl_logprob = calc_masked_log_probs(ref_kl_logits, kl_input_ids, kl_loss_mask[:, 1:]).sum(-1) ref_chosen_logprob = ref_logprob[chosen_index] ref_rejected_logprob = ref_logprob[rejected_index] loss, chosen_rewards, rejected_rewards, kl = self.kto_loss( chosen_logprob, rejected_logprob, kl_logprob, ref_chosen_logprob, ref_rejected_logprob, ref_kl_logprob ) self.booster.backward(loss=loss, optimizer=self.optimizer) if self.num_train_step % self.accumulation_steps == self.accumulation_steps - 1: self.optimizer.step() self.optimizer.zero_grad() self.actor_scheduler.step() # sync loss_mean = all_reduce_mean(tensor=loss) chosen_rewards_mean = all_reduce_mean(tensor=chosen_rewards.mean()) rejected_rewards_mean = all_reduce_mean(tensor=rejected_rewards.mean()) self.accumulative_meter.add("chosen_rewards", chosen_rewards_mean.to(torch.float16).mean().item()) self.accumulative_meter.add("rejected_rewards", rejected_rewards_mean.to(torch.float16).mean().item()) self.accumulative_meter.add("loss", loss_mean.to(torch.float16).detach().item()) if i % self.accumulation_steps == self.accumulation_steps - 1: self.num_train_step += 1 step_bar.update() # logging if self.writer and is_rank_0(): self.writer.add_scalar("train/loss", self.accumulative_meter.get("loss"), self.num_train_step) self.writer.add_scalar("train/lr", self.optimizer.param_groups[0]["lr"], self.num_train_step) self.writer.add_scalar( "train/chosen_rewards", self.accumulative_meter.get("chosen_rewards"), self.num_train_step ) self.writer.add_scalar( "train/rejected_rewards", self.accumulative_meter.get("rejected_rewards"), self.num_train_step, ) self.writer.add_scalar( "train/margin", self.accumulative_meter.get("chosen_rewards") - self.accumulative_meter.get("rejected_rewards"), self.num_train_step, ) self.accumulative_meter.reset() if self.save_dir is not None and (self.num_train_step + 1) % self.save_interval == 0: # save checkpoint self.coordinator.print_on_master("\nStart saving model checkpoint with running states") save_checkpoint( save_dir=self.save_dir, booster=self.booster, model=self.model, optimizer=self.optimizer, lr_scheduler=self.actor_scheduler, epoch=epoch, step=i + 1, batch_size=batch_size, coordinator=self.coordinator, ) self.coordinator.print_on_master( f"Saved checkpoint at epoch {epoch} step {self.save_interval} at folder {self.save_dir}" ) step_bar.close() def _eval(self, epoch: int): """ Args: epoch int: the number of current epoch """ if self.eval_dataloader is None: self.coordinator.print_on_master("No eval dataloader is provided, skip evaluation") return self.model.eval() self.accumulative_meter.reset() step_bar = trange( len(self.train_dataloader) // self.accumulation_steps, desc=f"Epoch {epoch + 1}/{self.max_epochs}", disable=not is_rank_0(), ) for i, batch in enumerate(self.train_dataloader): batch = to_device(batch, self.device) (input_ids, attention_mask, loss_mask, label, kl_input_ids, kl_attention_mask, kl_loss_mask) = ( batch["input_ids"], batch["attention_mask"], batch["loss_mask"], batch["label"], batch["kl_input_ids"], batch["kl_attention_mask"], batch["kl_loss_mask"], ) batch_size = input_ids.size()[0] # actor logits with torch.no_grad(): # calculate KL term with KT data kl_logits = self.model( input_ids=kl_input_ids, attention_mask=kl_attention_mask, )["logits"] logits = self.model( input_ids=input_ids, attention_mask=attention_mask, )["logits"] logprob = calc_masked_log_probs(logits, input_ids, loss_mask[:, 1:]).sum(-1) kl_logprob = calc_masked_log_probs(kl_logits, kl_input_ids, kl_loss_mask[:, 1:]).sum(-1) chosen_index = [i for i in range(batch_size) if label[i] == 1] rejected_index = [i for i in range(batch_size) if label[i] == 0] chosen_logprob = logprob[chosen_index] rejected_logprob = logprob[rejected_index] with torch.no_grad(): ref_kl_logits = self.ref_model( input_ids=kl_input_ids, attention_mask=kl_attention_mask, )["logits"] ref_logits = self.ref_model( input_ids=input_ids, attention_mask=attention_mask, )["logits"] ref_logprob = calc_masked_log_probs(ref_logits, input_ids, loss_mask[:, 1:]).sum(-1) ref_kl_logprob = calc_masked_log_probs(ref_kl_logits, kl_input_ids, kl_loss_mask[:, 1:]).sum(-1) ref_chosen_logprob = ref_logprob[chosen_index] ref_rejected_logprob = ref_logprob[rejected_index] loss, chosen_rewards, rejected_rewards, kl = self.kto_loss( chosen_logprob, rejected_logprob, kl_logprob, ref_chosen_logprob, ref_rejected_logprob, ref_kl_logprob ) # sync loss_mean = all_reduce_mean(tensor=loss) chosen_rewards_mean = all_reduce_mean(tensor=chosen_rewards.mean()) rejected_rewards_mean = all_reduce_mean(tensor=rejected_rewards.mean()) self.accumulative_meter.add("chosen_rewards", chosen_rewards_mean.to(torch.float16).mean().item()) self.accumulative_meter.add("rejected_rewards", rejected_rewards_mean.to(torch.float16).mean().item()) self.accumulative_meter.add("loss", loss_mean.to(torch.float16).detach().item()) self.accumulative_meter.add( "margin", (chosen_rewards_mean - rejected_rewards_mean).to(torch.float16).mean().item() ) step_bar.update() msg = "Evaluation Result:\n" for tag in ["loss", "chosen_rewards", "rejected_rewards", "margin"]: msg = msg + f"{tag}: {self.accumulative_meter.get(tag)}\n" self.coordinator.print_on_master(msg) os.makedirs(self.save_dir, exist_ok=True) with open(os.path.join(self.save_dir, f"eval_result_epoch{epoch}.txt"), "w") as f: f.write(msg) step_bar.close()