refactor: 重构打包模块,新增 BFD/FFD/Greedy 三种 bin-packing 算法,默认 BFD

- 将 pipeline/packing.py 拆分为 packing/ 子包 (base/stream/binpack)
- 新增 BfdPacker(默认)/FfDPacker/GreedyPacker,移除 StreamingPacker
- 超长序列直接截断至 pack_size
- group_size 语义改为"每 N 个 chunk 合并为一块",默认 1000
- 新增 AutoTokenizer.token_to_id(),修复 ChatML 中 hacky 的 nl_id 获取
- pad_value 默认改为 2(pad_token_id),position_ids pad=0, loss_mask pad=False
- 新增 position_ids 打包后归零一致性测试
- scripts/cache_h5.py 新增 --pack-algo 参数
This commit is contained in:
2026-07-03 16:17:27 +08:00
parent 2f919e9243
commit 598e1ce4ae
14 changed files with 715 additions and 295 deletions
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"""Sequence packing algorithms for LLM training data.
Available packers:
- BfdPacker: Best-Fit Decreasing, samples never split (default)
- FfDPacker: First-Fit Decreasing, samples never split
- GreedyPacker: First-fit in input order, samples never split
"""
from typing import Dict, List, Optional, Union
import torch
from pipeline.packing.base import BasePacker
from pipeline.packing.binpack import GreedyPacker, FfDPacker, BfdPacker
def pack_tensors(
tensors: Dict[str, List[torch.Tensor]],
pack_size: int,
pad_value: Union[int, bool] = 0,
dtypes: Optional[Dict[str, torch.dtype]] = None,
pad_values: Optional[Dict[str, Union[int, bool]]] = None,
algo: Optional[Union[str, BasePacker]] = None,
) -> Dict[str, List[torch.Tensor]]:
"""Pack multiple named tensor groups in parallel.
Each group is packed independently with its own packer instance.
Args:
tensors: Dict mapping key names to lists of 1D tensors.
pack_size: Fixed chunk length.
pad_value: Default padding value, used for keys not in pad_values.
dtypes: Optional per-key dtype declarations.
pad_values: Optional per-key padding values (e.g. pad_token_id for
'sequence', False for 'loss_mask', 0 for 'position_ids').
algo: Packing algorithm to use. Can be 'bfd' (default),
'ffd', 'greedy', or a BasePacker instance.
Returns:
Dict mapping key names to lists of packed tensors.
"""
if dtypes is None:
dtypes = {}
if pad_values is None:
pad_values = {}
output: Dict[str, List[torch.Tensor]] = {}
for key, seqs in tensors.items():
key_pad = pad_values.get(key, pad_value)
actual_packer = _resolve_algo(algo, pack_size, key_pad)
dtype = dtypes.get(key)
if dtype is not None:
actual_packer.dtype = dtype
output[key] = actual_packer.pack(seqs)
return output
def _resolve_algo(
algo: Optional[Union[str, BasePacker]],
pack_size: int,
pad_value: Union[int, bool],
) -> BasePacker:
if algo is None or algo == "bfd":
return BfdPacker(pack_size, pad_value)
if isinstance(algo, BasePacker):
cls = type(algo)
return cls(pack_size, pad_value)
if algo == "ffd":
return FfDPacker(pack_size, pad_value)
if algo == "greedy":
return GreedyPacker(pack_size, pad_value)
raise ValueError(
f"Unknown packing algorithm: {algo}. "
f"Choose from: bfd, ffd, greedy"
)
__all__ = [
"BasePacker",
"BfdPacker",
"FfDPacker",
"GreedyPacker",
"pack_tensors",
]
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from abc import ABC, abstractmethod
from typing import List, Optional, Union
import torch
from torch import Tensor
class BasePacker(ABC):
"""Abstract base class for sequence packing algorithms.
All packers must implement pack() and reset().
pack() takes a list of 1D tensors and returns a list of packed fixed-size tensors.
"""
def __init__(
self,
pack_size: int,
pad_value: Union[int, bool] = 0,
dtype: Optional[torch.dtype] = None,
):
self.pack_size = pack_size
self.pad_value = pad_value
self.dtype = dtype
@abstractmethod
def pack(self, sequences: List[Tensor]) -> List[Tensor]:
"""Pack sequences into fixed-size chunks."""
...
@abstractmethod
def reset(self) -> None:
"""Reset packer state for instance reuse."""
...
def _validate_and_normalize(self, sequences: List[Tensor]) -> List[Tensor]:
"""Validate 1D tensors and unify dtype."""
if self.dtype is None and sequences:
self.dtype = sequences[0].dtype
normalized: List[Tensor] = []
for i, seq in enumerate(sequences):
if seq.dim() != 1:
raise ValueError(
f"Expected 1D tensor at index {i}, got {seq.dim()}D tensor with shape {seq.shape}"
)
if seq.dtype != self.dtype:
seq = seq.to(self.dtype)
normalized.append(seq)
return normalized
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from typing import List, Optional, Union
import torch
from torch import Tensor
from pipeline.packing.base import BasePacker
from pipeline.utils import error_handler
def _truncate(tokens: List, max_len: int) -> List:
return tokens[:max_len]
def _pad_bin(bin_list: List, target_len: int, pad_value: Union[int, bool], dtype: torch.dtype) -> Tensor:
bin_list.extend([pad_value] * (target_len - len(bin_list)))
return torch.tensor(bin_list, dtype=dtype)
class GreedyPacker(BasePacker):
"""Greedy first-fit packer (no sorting).
Sequences are packed in input order into the first bin with enough space.
Overlong sequences (> pack_size) are truncated to pack_size.
"""
def __init__(
self,
pack_size: int,
pad_value: Union[int, bool] = 0,
dtype: Optional[torch.dtype] = None,
):
super().__init__(pack_size, pad_value, dtype)
self._bins: List[List] = []
def reset(self) -> None:
self._bins = []
@error_handler()
def pack(self, sequences: List[Tensor]) -> List[Tensor]:
if not sequences:
return []
normalized = self._validate_and_normalize(sequences)
self._bins = []
pack_size = self.pack_size
pad_value = self.pad_value
for seq in normalized:
seq_len = int(seq.shape[0])
if seq_len > pack_size:
self._bins.append(_truncate(seq.tolist(), pack_size))
continue
placed = False
for bin_list in self._bins:
if len(bin_list) + seq_len <= pack_size:
bin_list.extend(seq.tolist())
placed = True
break
if not placed:
self._bins.append(list(seq.tolist()))
packages: List[Tensor] = []
for bin_list in self._bins:
packages.append(_pad_bin(bin_list, pack_size, pad_value, self.dtype))
return packages
class FfDPacker(BasePacker):
"""First-Fit Decreasing (FFD) bin-packing packer.
Sequences are sorted by descending length, then packed into the first
bin with enough space. Overlong sequences are truncated to pack_size.
"""
def __init__(
self,
pack_size: int,
pad_value: Union[int, bool] = 0,
dtype: Optional[torch.dtype] = None,
):
super().__init__(pack_size, pad_value, dtype)
self._bins: List[List] = []
def reset(self) -> None:
self._bins = []
@error_handler()
def pack(self, sequences: List[Tensor]) -> List[Tensor]:
if not sequences:
return []
normalized = self._validate_and_normalize(sequences)
self._bins = []
pack_size = self.pack_size
pad_value = self.pad_value
indexed = [(int(s.shape[0]), s) for s in normalized]
indexed.sort(key=lambda x: x[0], reverse=True)
for seq_len, seq in indexed:
if seq_len > pack_size:
self._bins.append(_truncate(seq.tolist(), pack_size))
continue
placed = False
for bin_list in self._bins:
if len(bin_list) + seq_len <= pack_size:
bin_list.extend(seq.tolist())
placed = True
break
if not placed:
self._bins.append(list(seq.tolist()))
packages: List[Tensor] = []
for bin_list in self._bins:
packages.append(_pad_bin(bin_list, pack_size, pad_value, self.dtype))
return packages
class BfdPacker(BasePacker):
"""Best-Fit Decreasing (BFD) bin-packing packer.
Sequences are sorted by descending length, then packed into the bin
that minimizes remaining space (tightest fit).
Overlong sequences are truncated to pack_size.
"""
def __init__(
self,
pack_size: int,
pad_value: Union[int, bool] = 0,
dtype: Optional[torch.dtype] = None,
):
super().__init__(pack_size, pad_value, dtype)
self._bins: List[List] = []
def reset(self) -> None:
self._bins = []
@error_handler()
def pack(self, sequences: List[Tensor]) -> List[Tensor]:
if not sequences:
return []
normalized = self._validate_and_normalize(sequences)
self._bins = []
pack_size = self.pack_size
pad_value = self.pad_value
indexed = [(int(s.shape[0]), s) for s in normalized]
indexed.sort(key=lambda x: x[0], reverse=True)
for seq_len, seq in indexed:
if seq_len > pack_size:
self._bins.append(_truncate(seq.tolist(), pack_size))
continue
best_idx = -1
best_remain = pack_size + 1
for i, bin_list in enumerate(self._bins):
remain = pack_size - len(bin_list)
if seq_len <= remain < best_remain:
best_remain = remain
best_idx = i
if best_idx >= 0:
self._bins[best_idx].extend(seq.tolist())
else:
self._bins.append(list(seq.tolist()))
packages: List[Tensor] = []
for bin_list in self._bins:
packages.append(_pad_bin(bin_list, pack_size, pad_value, self.dtype))
return packages