mirror of
https://github.com/hiyouga/LLaMA-Factory.git
synced 2025-08-02 11:42:49 +08:00
206 lines
8.1 KiB
Python
206 lines
8.1 KiB
Python
from collections import defaultdict
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from contextlib import nullcontext
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from types import MethodType
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from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, Union
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import torch
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from transformers import Trainer
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from trl import KTOTrainer
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from trl.trainer.utils import disable_dropout_in_model
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from ...extras.constants import IGNORE_INDEX
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from ..utils import create_custom_optimzer, create_custom_scheduler
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if TYPE_CHECKING:
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from transformers import PreTrainedModel
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from ...hparams import FinetuningArguments
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class CustomKTOTrainer(KTOTrainer):
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def __init__(
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self,
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model: Union["PreTrainedModel", torch.nn.Module],
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ref_model: Optional[Union["PreTrainedModel", torch.nn.Module]],
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finetuning_args: "FinetuningArguments",
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disable_dropout: bool = True,
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**kwargs,
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):
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if disable_dropout:
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disable_dropout_in_model(model)
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if ref_model is not None:
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disable_dropout_in_model(ref_model)
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self.finetuning_args = finetuning_args
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self.reference_free = False
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self.use_dpo_data_collator = True # hack to avoid warning
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self.generate_during_eval = False # disable at evaluation
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self.label_pad_token_id = IGNORE_INDEX
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self.padding_value = 0
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self.is_encoder_decoder = model.config.is_encoder_decoder
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self.precompute_ref_log_probs = False
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self._precomputed_train_ref_log_probs = False
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self._precomputed_eval_ref_log_probs = False
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self._peft_has_been_casted_to_bf16 = False
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self.ref_model = ref_model
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self._stored_metrics = defaultdict(lambda: defaultdict(list))
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# KTO parameter
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self.beta = finetuning_args.kto_beta
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self.ftx_gamma = finetuning_args.kto_ftx
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self.desirable_weight = finetuning_args.kto_desirable_weight
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self.undesirable_weight = finetuning_args.kto_undesirable_weight
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Trainer.__init__(self, model=model, **kwargs)
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if not hasattr(self, "accelerator"):
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raise AttributeError("Please update `transformers`.")
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if ref_model is not None:
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if self.is_deepspeed_enabled:
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if not (
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getattr(ref_model, "is_loaded_in_8bit", False) or getattr(ref_model, "is_loaded_in_4bit", False)
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): # quantized models are already set on the correct device
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self.ref_model = self._prepare_deepspeed(self.ref_model)
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else:
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self.ref_model = self.accelerator.prepare_model(self.ref_model, evaluation_mode=True)
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if finetuning_args.use_badam:
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from badam import clip_grad_norm_for_sparse_tensor
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self.accelerator.clip_grad_norm_ = MethodType(clip_grad_norm_for_sparse_tensor, self.accelerator)
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def create_optimizer(self) -> "torch.optim.Optimizer":
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if self.optimizer is None:
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self.optimizer = create_custom_optimzer(self.model, self.args, self.finetuning_args)
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return super().create_optimizer()
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def create_scheduler(
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self, num_training_steps: int, optimizer: Optional["torch.optim.Optimizer"] = None
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) -> "torch.optim.lr_scheduler.LRScheduler":
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create_custom_scheduler(self.args, num_training_steps, optimizer)
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return super().create_scheduler(num_training_steps, optimizer)
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def sft_loss(self, chosen_logits: "torch.FloatTensor", chosen_labels: "torch.LongTensor") -> "torch.Tensor":
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r"""
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Computes supervised cross-entropy loss of given labels under the given logits.
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Returns:
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A tensor of shape (batch_size,) containing the cross-entropy loss of each samples.
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"""
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all_logps = self.get_batch_logps(chosen_logits, chosen_labels, average_log_prob=True)
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return -all_logps.nanmean()
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def forward(
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self, model: "PreTrainedModel", batch: Dict[str, "torch.Tensor"]
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) -> Tuple["torch.Tensor", "torch.Tensor", "torch.Tensor", "torch.Tensor", "torch.Tensor"]:
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with torch.no_grad():
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KL_logits = model(
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batch["KL_completion_input_ids"],
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attention_mask=batch["KL_completion_attention_mask"],
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).logits
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completion_logits = model(
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batch["input_ids"],
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attention_mask=batch["attention_mask"],
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).logits
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completion_logps = self.get_batch_logps(
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completion_logits,
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batch["labels"],
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average_log_prob=False,
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is_encoder_decoder=self.is_encoder_decoder,
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label_pad_token_id=self.label_pad_token_id,
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)
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KL_logps = self.get_batch_logps(
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KL_logits,
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batch["kl_labels"],
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average_log_prob=False,
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is_encoder_decoder=self.is_encoder_decoder,
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label_pad_token_id=self.label_pad_token_id,
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)
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if completion_logps.shape[0] != len(batch["tag"]):
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raise ValueError(
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"There is a mismatch between the number of examples in this batch and the number of "
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"examples for which an output sequence was predicted."
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)
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chosen_idx = [i for i in range(completion_logps.shape[0]) if batch["tag"][i]]
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rejected_idx = [i for i in range(completion_logps.shape[0]) if not batch["tag"][i]]
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chosen_logps = completion_logps[chosen_idx, ...]
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rejected_logps = completion_logps[rejected_idx, ...]
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chosen_logits = completion_logits[chosen_idx, ...]
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rejected_logits = completion_logits[rejected_idx, ...]
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return (chosen_logps, rejected_logps, chosen_logits, rejected_logits, KL_logps)
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def get_batch_loss_metrics(
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self,
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model,
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batch: Dict[str, Union[List, torch.LongTensor]],
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):
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"""Compute the KTO loss and other metrics for the given batch of inputs for train or test."""
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metrics = {}
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batch = {k: (v.to(self.accelerator.device) if isinstance(v, torch.Tensor) else v) for k, v in batch.items()}
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(
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policy_chosen_logps,
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policy_rejected_logps,
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policy_chosen_logits,
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policy_rejected_logits,
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policy_KL_logps,
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) = self.forward(model, batch)
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with torch.no_grad():
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if self.ref_model is None:
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ref_model = self.model
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ref_context = self.accelerator.unwrap_model(self.model).disable_adapter()
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else:
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ref_model = self.ref_model
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ref_context = nullcontext()
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with ref_context:
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(
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reference_chosen_logps,
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reference_rejected_logps,
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_,
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_,
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reference_KL_logps,
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) = self.forward(ref_model, batch)
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losses, chosen_rewards, rejected_rewards, kl = self.kto_loss(
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policy_chosen_logps,
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policy_rejected_logps,
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policy_KL_logps,
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reference_chosen_logps,
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reference_rejected_logps,
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reference_KL_logps,
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)
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losses = losses.nanmean()
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if self.ftx_gamma > 1e-6 and len(batch["labels"][batch['tag']])>0:
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losses += self.ftx_gamma * self.sft_loss(policy_chosen_logits, batch["labels"][batch['tag']])
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num_chosen = torch.Tensor([len(chosen_rewards)]).to(self.accelerator.device)
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num_rejected = torch.Tensor([len(rejected_rewards)]).to(self.accelerator.device)
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all_num_chosen = self.accelerator.gather(num_chosen).sum().item()
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all_num_rejected = self.accelerator.gather(num_rejected).sum().item()
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if all_num_chosen > 0:
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metrics["rewards/chosen_sum"] = self.accelerator.gather(chosen_rewards.nansum()).nansum().item()
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metrics["logps/chosen_sum"] = self.accelerator.gather(policy_chosen_logps.nansum()).nansum().item()
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metrics["count/chosen"] = all_num_chosen
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if all_num_rejected > 0:
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metrics["rewards/rejected_sum"] = self.accelerator.gather(rejected_rewards.nansum()).nansum().item()
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metrics["logps/rejected_sum"] = self.accelerator.gather(policy_rejected_logps.nansum()).nansum().item()
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metrics["count/rejected"] = all_num_rejected
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metrics["kl"] = kl.item()
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return losses, metrics |