mirror of https://github.com/hpcaitech/ColossalAI
130 lines
4.2 KiB
Python
130 lines
4.2 KiB
Python
from typing import Any, Dict, List, Optional, Union
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import torch
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def unbind_batch(batch: Dict[str, torch.Tensor]) -> List[Dict[str, torch.Tensor]]:
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batches = []
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for k, v in batch.items():
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if len(batches) == 0:
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unbinded_tensors = v.unbind(0)
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batches = [{k: tensor} for tensor in unbinded_tensors]
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else:
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unbinded_tensors = v.unbind(0)
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assert len(batches) == len(unbinded_tensors)
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for i, tensor in enumerate(unbinded_tensors):
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batches[i][k] = tensor
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return batches
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def bind_batch(batches: List[Dict[str, torch.Tensor]]) -> Dict[str, torch.Tensor]:
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batch = {}
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for k in batches[0].keys():
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batch[k] = torch.stack([batch[k] for batch in batches], dim=0)
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return batch
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def pre_send(batch: Dict[str, torch.Tensor]) -> Dict[str, torch.Tensor]:
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# compress mask to save bandwidth
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if "attention_mask" in batch:
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batch["attention_mask"] = batch["attention_mask"].to(torch.bool)
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if "action_mask" in batch:
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batch["action_mask"] = batch["action_mask"].to(torch.bool)
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return batch
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def post_recv(batch: Dict[str, torch.Tensor]) -> Dict[str, torch.Tensor]:
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# decompress mask
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if "attention_mask" in batch:
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batch["attention_mask"] = batch["attention_mask"].to(torch.int)
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if "action_mask" in batch:
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batch["action_mask"] = batch["action_mask"].to(torch.int)
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return batch
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def update_by_default(data: Dict[str, Any], default: Dict[str, Any]) -> Dict[str, Any]:
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data = data.copy()
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for k, v in default.items():
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if k not in data:
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data[k] = v
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return data
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def log_probs_from_logits(logits: torch.Tensor, labels: torch.Tensor) -> torch.Tensor:
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"""
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Compute the log probabilities from logits for the given labels.
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Args:
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logits (torch.Tensor): The input logits.
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labels (torch.Tensor): The target labels.
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Returns:
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torch.Tensor: The log probabilities corresponding to the labels.
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"""
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log_probs = torch.log_softmax(logits, dim=-1)
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per_label_logps = log_probs.gather(dim=-1, index=labels.unsqueeze(-1))
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return per_label_logps.squeeze(-1)
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def calc_action_log_probs(logits: torch.Tensor, sequences: torch.LongTensor, num_actions: int) -> torch.Tensor:
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"""Calculate action log probs.
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Args:
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output (torch.Tensor): Output tensor of Actor.forward.logits.
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sequences (torch.LongTensor): Input sequences.
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num_actions (int): Number of actions.
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Returns:
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torch.Tensor: Action log probs.
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"""
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log_probs = log_probs_from_logits(logits[:, :-1, :], sequences[:, 1:])
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return log_probs[:, -num_actions:]
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def masked_mean(tensor: torch.Tensor, mask: torch.Tensor, dim: int = 1) -> torch.Tensor:
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"""
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Compute the masked mean of a tensor along a specified dimension.
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Args:
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tensor (torch.Tensor): The input tensor.
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mask (torch.Tensor): The mask tensor with the same shape as the input tensor.
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dim (int, optional): The dimension along which to compute the mean. Default is 1.
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Returns:
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torch.Tensor: The masked mean tensor.
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"""
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tensor = tensor * mask
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tensor = tensor.sum(dim=dim)
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mask_sum = mask.sum(dim=dim)
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mean = tensor / (mask_sum + 1e-8)
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return mean
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def compute_reward_ppo(
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r: Union[torch.Tensor, float],
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kl_coef: float,
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log_probs: torch.Tensor,
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log_probs_base: torch.Tensor,
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action_mask: Optional[torch.Tensor] = None,
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reward_eps=5,
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) -> torch.Tensor:
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"""
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Args:
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log_probs: [batch_size, response_length]
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log_probs_base: [batch_size, response_length]
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action_mask: [batch_size, response_length]
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r: float
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Returns:
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reward: [batch_size, response_length]
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"""
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log_ratio = log_probs - log_probs_base # address numerical instability issue
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kl = -kl_coef * log_ratio * action_mask
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reward = kl
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r_clip = torch.clamp(r, -reward_eps, reward_eps)
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for i in range(action_mask.size(0)):
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assert action_mask[i].sum() > 0
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reward[i, : action_mask[i].sum()] += r_clip[i]
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reward[i, action_mask[i].sum() :] *= 0
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return reward, ((log_ratio * (log_ratio < 10)).exp() - 1 - log_ratio) * action_mask
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