Files
AstrAI/astrai/trainer/train_context.py
T
ViperEkura 95c43368ae refactor: unify rollout onto inference engine KV-cache path
- RolloutGenerator now delegates prefill/decode to InferenceScheduler.run_batch (sync API, no background thread), sharing one KV-cache code path with the inference server and eliminating O(n^2) recompute in rollout
- Add sample(return_logprobs=) and Executor.execute_decode(return_logprobs=) to expose behaviour-policy log-probs through the engine; Task gains output_logprobs
- RolloutResult now subclasses RawRollout (adds rewards only), removing duplicated fields
- RolloutRunner.__call__ returns (result, is_fresh) instead of relying on object identity, removing the fragile refresh-detection contract
- Remove O(n^2) generate_responses helper and dead code (_tokenize_prompts, unused old_model arg)
- train_context.py wires InferenceScheduler directly instead of hand-rolling SamplingPipeline
- Tests: +11 covering return_logprobs, run_batch, and KV-cache-backed rollout semantics; 404 pass
2026-07-20 12:52:20 +08:00

267 lines
9.5 KiB
Python

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.core.scheduler import InferenceScheduler
from astrai.model.components.lora import inject_lora
from astrai.parallel.executor import BaseExecutor, ExecutorFactory
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.rollout import RolloutGenerator, RolloutRunner
from astrai.trainer.strategy import BaseStrategy, StrategyFactory, create_ref_model
@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)
grad_norm: Optional[float] = field(default=None)
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)
@property
def optimizer_step(self) -> int:
return self.consumed_samples // (
self.config.batch_per_device
* self.world_size
* self.config.grad_accum_steps
)
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:
cfg = self.config
device = get_current_device()
executor = ExecutorFactory.create(
cfg.parallel_mode,
grad_accum_steps=cfg.grad_accum_steps,
**cfg.executor_kwargs,
)
model_config = {}
if self._param_path:
config_path = Path(self._param_path) / "config.json"
if config_path.exists():
model_config = load_json(config_path)
preloaded_state_dict = None
preloaded_epoch = cfg.start_epoch
preloaded_consumed = cfg.start_samples * get_world_size()
preloaded_checkpoint = None
if self._param_path:
checkpoint = Checkpoint.load_any(self._param_path)
if checkpoint is not None:
preloaded_state_dict = checkpoint.state_dict
if checkpoint.config:
model_config = checkpoint.config
if self._resume:
preloaded_epoch = checkpoint.epoch or cfg.start_epoch
if checkpoint.consumed_samples > 0:
per_step = (
cfg.batch_per_device
* get_world_size()
* cfg.grad_accum_steps
)
preloaded_consumed = (
checkpoint.consumed_samples // per_step
) * per_step
else:
preloaded_consumed = cfg.start_samples * get_world_size()
preloaded_checkpoint = checkpoint
if not model_config and hasattr(cfg.model_fn(), "config"):
model_config = cfg.model_fn().config.to_dict()
def _before_wrap(m):
m = m.to(device=device)
if preloaded_state_dict is not None:
m.load_state_dict(preloaded_state_dict, strict=False)
if cfg.lora is not None:
inject_lora(
m,
r=cfg.lora.r,
alpha=cfg.lora.alpha,
target_modules=set(cfg.lora.target_modules),
)
return m
context = TrainContext(
world_size=get_world_size(),
rank=get_rank(),
config=cfg,
model_config=model_config,
executor=executor,
epoch=preloaded_epoch,
consumed_samples=preloaded_consumed,
checkpoint=preloaded_checkpoint,
)
context.model, context.optimizer, context.scheduler = executor.prepare(
cfg.model_fn,
cfg.optimizer_fn,
cfg.scheduler_fn,
before_wrap=_before_wrap,
)
train_dataset = cfg.dataset
val_dataset = cfg.val_dataset
if val_dataset is None and cfg.val_split is not None:
n_total = len(cfg.dataset)
n_val = max(1, int(n_total * cfg.val_split))
n_train = n_total - n_val
generator = torch.Generator().manual_seed(cfg.random_seed)
train_dataset, val_dataset = random_split(
cfg.dataset, [n_train, n_val], generator=generator
)
sampler_offset = context.consumed_samples // context.world_size
sampler = RDSampler(
data_source=train_dataset,
start_epoch=context.epoch,
start_iter=sampler_offset,
seed=cfg.random_seed,
)
context.dataloader = DataLoader(
train_dataset,
batch_size=cfg.batch_per_device,
sampler=sampler,
num_workers=cfg.num_workers,
pin_memory=cfg.pin_memory,
prefetch_factor=cfg.prefetch_factor,
collate_fn=cfg.collate_fn,
)
if val_dataset is not None:
val_sampler = RDSampler(
data_source=val_dataset,
start_epoch=0,
start_iter=0,
seed=cfg.random_seed,
shuffle=False,
)
context.val_dataloader = DataLoader(
val_dataset,
batch_size=cfg.batch_per_device,
sampler=val_sampler,
num_workers=cfg.num_workers,
pin_memory=cfg.pin_memory,
prefetch_factor=cfg.prefetch_factor,
collate_fn=cfg.collate_fn,
)
if context.checkpoint and context.checkpoint.extra:
extra = context.checkpoint.extra
for name in ("optimizer", "scheduler"):
if name in extra:
obj = getattr(context, name, None)
if obj is not None:
obj.load_state_dict(extra[name])
strategy_kwargs = dict(cfg.extra_kwargs)
needs_ref = cfg.strategy in (
"dpo",
"grpo",
"online_grpo",
"online_dpo",
)
needs_old = cfg.strategy in ("grpo", "online_grpo")
if needs_ref:
ref_model = create_ref_model(
cfg.model_fn, executor.unwrap_model(context.model)
).to(device=device)
strategy_kwargs["ref_model"] = ref_model
old_model = None
if needs_old:
old_model = create_ref_model(
cfg.model_fn, executor.unwrap_model(context.model)
).to(device=device)
strategy_kwargs["old_model"] = old_model
context.strategy = StrategyFactory.create(
cfg.strategy,
model=context.model,
device=device,
executor=executor,
**strategy_kwargs,
)
# Enable online rollout when the train_type is an ``online_*`` variant.
is_online = cfg.strategy.startswith("online_")
if is_online:
if not context.strategy.supports_online():
raise ValueError(
f"Strategy '{cfg.strategy}' does not support online rollout"
)
if cfg.reward_model_fn is None:
raise ValueError("reward_model_fn is required for online RL strategies")
tokenizer = AutoTokenizer.from_pretrained(self._param_path)
reward_model = cfg.reward_model_fn()
scheduler = InferenceScheduler(
model=context.model,
tokenizer=tokenizer,
max_batch_size=strategy_kwargs.get("group_size", 8)
* max(1, cfg.batch_size or 1),
max_seq_len=getattr(context.model.config, "max_len", None),
max_prompt_len=getattr(context.model.config, "max_len", 4096),
)
generator = RolloutGenerator(
scheduler=scheduler,
tokenizer=tokenizer,
max_tokens=cfg.rollout_max_tokens,
group_size=strategy_kwargs.get("group_size", 8),
temperature=cfg.rollout_temperature,
top_k=cfg.rollout_top_k,
top_p=cfg.rollout_top_p,
)
runner = RolloutRunner(
generator=generator,
reward_model=reward_model,
rollout_interval=cfg.rollout_interval,
)
context.strategy.set_rollout_runner(runner)
return context