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AstrAI/astrai/trainer/train_context.py
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Python

import logging
import threading
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Dict, Optional, Self
import torch
import torch.nn as nn
from torch.utils.data import DataLoader, random_split
from astrai.config.train_config import TrainConfig
from astrai.dataset import RDSampler
from astrai.inference.scheduler import InferenceScheduler
from astrai.model.components.lora import inject_lora
from astrai.parallel.executor import BaseExecutor, ExecutorFactory, create_ref_model
from astrai.parallel.setup import get_current_device, get_rank, get_world_size
from astrai.protocols import OptimizerProtocol, SchedulerProtocol
from astrai.serialization import Checkpoint, load_json
from astrai.tokenize import AutoTokenizer
from astrai.trainer.metric_util import GradSNRTracker
from astrai.trainer.rollout import RolloutGenerator, RolloutRunner
from astrai.trainer.strategy import BaseStrategy, StrategyFactory
logger = logging.getLogger(__name__)
@dataclass
class TrainContext:
model: nn.Module = field(default=None)
strategy: BaseStrategy = field(default=None)
dataloader: DataLoader = field(default=None)
optimizer: OptimizerProtocol = field(default=None)
scheduler: SchedulerProtocol = field(default=None)
checkpoint: Checkpoint = field(default=None)
config: TrainConfig = field(default=None)
model_config: dict = field(default_factory=dict)
executor: BaseExecutor = field(default=None)
epoch: int = field(default=0)
consumed_samples: int = field(default=0)
loss: float = field(default=0.0)
metrics: Dict[str, float] = field(default_factory=dict)
grad_norm: Optional[float] = field(default=None)
grad_snr_tracker: GradSNRTracker = field(default_factory=GradSNRTracker)
val_dataloader: Optional[DataLoader] = field(default=None)
val_loss: Optional[float] = field(default=None)
world_size: int = field(default=1)
rank: int = field(default=0)
kwargs: Dict[str, Any] = field(default_factory=dict)
_stop_event: threading.Event = field(default_factory=threading.Event)
@property
def stop_requested(self) -> bool:
return self._stop_event.is_set()
def request_stop(self) -> None:
self._stop_event.set()
@property
def optimizer_step(self) -> int:
return self.consumed_samples // (
self.config.batch_per_device
* self.world_size
* self.config.grad_accum_steps
)
@dataclass
class _PreloadedState:
model_config: dict = field(default_factory=dict)
state_dict: Optional[dict] = None
epoch: int = 0
consumed_samples: int = 0
checkpoint: Optional[Checkpoint] = None
class TrainContextBuilder:
def __init__(
self,
config: TrainConfig,
):
self.config = config
self._param_path: Optional[str] = None
self._resume: bool = False
def with_param_path(self, param_path: Optional[str], resume: bool = False) -> Self:
self._param_path = param_path
self._resume = resume
return self
def build(self) -> TrainContext:
# Resolve persisted state.
preloaded_state = self._load_preloaded_state()
# Build the core training components and restore their persisted state.
executor = self._create_executor()
context = self._create_context(preloaded_state, executor)
self._prepare_model(context, executor, preloaded_state)
self._restore_optimizer_state(context)
# Resolve datasets.
train_dataset, val_dataset = self._get_datasets()
self._create_dataloaders(context, train_dataset, val_dataset)
# Strategies depend on the prepared model; online rollout depends on both.
strategy_kwargs = self._create_strategy(context, executor)
self._configure_rollout(context, strategy_kwargs)
return context
def _create_executor(self) -> BaseExecutor:
cfg = self.config
return ExecutorFactory.create(
cfg.parallel_mode,
grad_accum_steps=cfg.grad_accum_steps,
**cfg.executor_kwargs,
)
def _load_preloaded_state(self) -> _PreloadedState:
cfg = self.config
state = _PreloadedState(
epoch=cfg.start_epoch,
consumed_samples=cfg.start_samples * get_world_size(),
)
if self._param_path:
config_path = Path(self._param_path) / "config.json"
if config_path.exists():
state.model_config = load_json(config_path)
checkpoint = Checkpoint.load_any(self._param_path)
if checkpoint is not None:
state.state_dict = checkpoint.state_dict
state.model_config = checkpoint.config or state.model_config
if self._resume:
state.epoch = checkpoint.epoch
per_step = (
cfg.batch_per_device * get_world_size() * cfg.grad_accum_steps
)
state.consumed_samples = (
checkpoint.consumed_samples // per_step * per_step
)
state.checkpoint = checkpoint
if not state.model_config and hasattr(cfg.model_fn(), "config"):
state.model_config = cfg.model_fn().config.to_dict()
return state
def _create_context(
self, state: _PreloadedState, executor: BaseExecutor
) -> TrainContext:
return TrainContext(
world_size=get_world_size(),
rank=get_rank(),
config=self.config,
model_config=state.model_config,
executor=executor,
epoch=state.epoch,
consumed_samples=state.consumed_samples,
checkpoint=state.checkpoint,
)
def _prepare_model(
self, context: TrainContext, executor: BaseExecutor, state: _PreloadedState
) -> None:
cfg = self.config
device = get_current_device()
def before_wrap(model):
model = model.to(device=device)
if cfg.lora is not None:
inject_lora(
model,
r=cfg.lora.r,
alpha=cfg.lora.alpha,
target_modules=set(cfg.lora.target_modules),
)
if state.state_dict is not None:
model.load_state_dict(state.state_dict, strict=False)
return model
def after_wrap(model):
if cfg.compile_mode is not None:
logger.info("torch.compile enabled (mode=%s)", cfg.compile_mode)
model = torch.compile(model, mode=cfg.compile_mode)
return model
context.model, context.optimizer, context.scheduler = executor.prepare(
cfg.model_fn,
cfg.optimizer_fn,
cfg.scheduler_fn,
before_wrap=before_wrap,
after_wrap=after_wrap,
)
def _get_datasets(self):
cfg = self.config
if cfg.val_dataset is not None or cfg.val_split is None:
return cfg.dataset, cfg.val_dataset
n_val = max(1, int(len(cfg.dataset) * cfg.val_split))
generator = torch.Generator().manual_seed(cfg.random_seed)
return random_split(
cfg.dataset, [len(cfg.dataset) - n_val, n_val], generator=generator
)
def _create_dataloaders(
self, context: TrainContext, train_dataset, val_dataset
) -> None:
sampler_offset = context.consumed_samples // context.world_size
if self._resume and sampler_offset > 0:
samples_per_replica = (
len(train_dataset) + context.world_size - 1
) // context.world_size
if samples_per_replica > 0:
context.epoch = sampler_offset // samples_per_replica
context.dataloader = self._create_dataloader(
train_dataset, context.epoch, sampler_offset
)
if val_dataset is not None:
context.val_dataloader = self._create_dataloader(
val_dataset, 0, 0, shuffle=False
)
def _create_dataloader(
self, dataset, epoch: int, start_iter: int, shuffle: bool = True
):
cfg = self.config
sampler = RDSampler(
dataset,
start_epoch=epoch,
start_iter=start_iter,
seed=cfg.random_seed,
shuffle=shuffle,
)
loader_kwargs = dict(
dataset=dataset,
batch_size=cfg.batch_per_device,
sampler=sampler,
num_workers=cfg.num_workers,
pin_memory=cfg.pin_memory,
collate_fn=cfg.collate_fn,
)
# PyTorch rejects prefetch_factor/persistent_workers when workers=0.
if cfg.num_workers > 0:
loader_kwargs["persistent_workers"] = cfg.persistent_workers
if cfg.prefetch_factor is not None:
loader_kwargs["prefetch_factor"] = cfg.prefetch_factor
return DataLoader(
**loader_kwargs,
)
def _restore_optimizer_state(self, context: TrainContext) -> None:
if context.checkpoint and context.checkpoint.extra:
for name in ("optimizer", "scheduler"):
if (
name in context.checkpoint.extra
and getattr(context, name, None) is not None
):
getattr(context, name).load_state_dict(
context.checkpoint.extra[name]
)
def _create_strategy(self, context: TrainContext, executor: BaseExecutor) -> dict:
cfg = self.config
kwargs = dict(cfg.extra_kwargs)
kwargs.setdefault("moe_aux_loss_coef", cfg.moe_aux_loss_coef)
if cfg.strategy in ("dpo", "grpo", "online_grpo", "online_dpo"):
kwargs["ref_model"] = create_ref_model(
cfg.model_fn,
executor=executor,
model=context.model,
device=get_current_device(),
)
if cfg.strategy in ("grpo", "online_grpo"):
kwargs["old_model"] = create_ref_model(
cfg.model_fn,
executor=executor,
model=context.model,
device=get_current_device(),
)
context.strategy = StrategyFactory.create(
cfg.strategy,
model=context.model,
device=get_current_device(),
executor=executor,
**kwargs,
)
return kwargs
def _configure_rollout(self, context: TrainContext, strategy_kwargs: dict) -> None:
cfg = self.config
if not cfg.strategy.startswith("online_"):
return
if not context.strategy.supports_online():
raise ValueError(
f"Strategy '{cfg.strategy}' does not support online rollout"
)
tokenizer = AutoTokenizer.from_pretrained(self._param_path)
group_size = strategy_kwargs.get("group_size", 1)
scheduler = InferenceScheduler(
model=context.model,
tokenizer=tokenizer,
max_batch_size=group_size * max(1, cfg.batch_per_device),
max_seq_len=getattr(context.model.config, "max_position_embeddings", None),
)
generator = RolloutGenerator(
scheduler=scheduler,
tokenizer=tokenizer,
max_tokens=cfg.rollout_max_tokens,
group_size=group_size,
temperature=cfg.rollout_temperature,
top_k=cfg.rollout_top_k,
top_p=cfg.rollout_top_p,
)
context.strategy.set_rollout_runner(
RolloutRunner(
generator=generator,
reward_model=cfg.reward_model_fn(),
rollout_interval=cfg.rollout_interval,
)
)