Files
lerobot/tests/fixtures/dummy_checkpoint_policy.py
T
Haoming Song ef88d4e52b feat(train): parallel training framework — FSDP2, HSDP, gradient accumulation, and DCP checkpoints (#4010)
* feat(train): parallel training engine with FSDP2, HSDP, and DCP checkpoints

Replace the FSDP1 training path with a config-owned parallel-training
engine:

- Topology and runtime configs (--parallelism.*, --accelerator.*):
  dp_replicate x dp_shard degrees select single-process, DDP (unchanged
  default), FSDP2, or HSDP; mixed precision, first-class gradient
  accumulation, and FSDP/DDP tuning knobs are mirrored as plain
  dataclasses that build the accelerate objects at runtime, so every
  run is reproducible from its train_config.json alone. Accelerate env
  vars are guarded against configuring the engine behind the config
  system's back.
- Declarative policy surface: policies declare FSDP2 wrap units
  (_fsdp_wrap_modules) and non-forward entry points
  (_fsdp_forward_methods); a shared engine resolves them around
  accelerator.prepare(). Context-parallel fields are reserved and
  validated to 1.
- Checkpoints: selectable --checkpoint_format (safetensors | dcp |
  safetensors_dcp); the sharded optimizer channel is always DCP;
  two-phase resume (step+RNG before prepare, DCP model/optimizer after)
  reshards across GPU-topology changes; lerobot-convert-dcp merges DCP
  shards into a distributable model.safetensors offline.
- Publishing: PreTrainedPolicy.push_model_to_hub is replaced by the
  free publish_trained_model (model + processors + card + train config,
  all-ranks gather with main-rank writes);
  PreTrainedPolicy._save_pretrained gathers state dicts internally,
  removing the state_dict= threading from save_pretrained.
- lerobot_train is restructured around the engine: optimizer built
  before the single prepare() call, deferred weight load on DCP
  resumes, collective save_checkpoint with no call-site rank branches,
  dp-world-size-based sample accounting.

Breaking changes: FSDP checkpoints from lerobot <= 0.6.x are not
resumable (weights stay loadable via from_pretrained; pin
lerobot==0.6.x to finish old runs); the `accelerate launch
--config_file` yaml flow is superseded by the config flags; training
autocast is owned exclusively by --accelerator.mixed_precision
(policy.dtype only casts parameters).

Also fixes: reward-model hub publishing crash (TypeError on extra
kwargs).

Verified by ~200 new CPU tests (config round-trips, checkpoint
round-trips per format, two-phase resume, publisher contracts,
converter equivalence, accelerate canaries), a 5-test 4-GPU suite
(FSDP2 save/resume bit-exactness, HSDP/DDP loss parity,
changed-topology resume, all-ranks save_pretrained, grad-accum
equivalence), and end-to-end ACT (1/4/8 GPUs) + FastWAM 6B
(FSDP2 + HSDP) training runs.
2026-08-06 19:16:41 +08:00

88 lines
2.7 KiB
Python

#!/usr/bin/env python
# Copyright 2026 The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""A minimal real PreTrainedPolicy for checkpoint/publish unit tests (CPU, tiny)."""
from dataclasses import dataclass
import torch
from torch import Tensor, nn
from lerobot.configs.policies import PreTrainedConfig
from lerobot.optim.optimizers import AdamConfig, OptimizerConfig
from lerobot.policies.pretrained import PreTrainedPolicy
@PreTrainedConfig.register_subclass("dummy_checkpoint")
@dataclass
class DummyCheckpointConfig(PreTrainedConfig):
hidden: int = 4
@property
def observation_delta_indices(self) -> list | None:
return None
@property
def action_delta_indices(self) -> list | None:
return None
@property
def reward_delta_indices(self) -> list | None:
return None
def get_optimizer_preset(self) -> OptimizerConfig:
return AdamConfig(lr=1e-3)
def get_scheduler_preset(self) -> None:
return None
def validate_features(self) -> None:
pass
class DummyCheckpointPolicy(PreTrainedPolicy):
config_class = DummyCheckpointConfig
name = "dummy_checkpoint"
def __init__(self, config: DummyCheckpointConfig, **kwargs):
super().__init__(config)
self.net = nn.Linear(config.hidden, config.hidden)
def get_optim_params(self) -> dict:
return self.parameters()
def reset(self) -> None:
pass
def forward(self, batch: dict[str, Tensor]) -> tuple[Tensor, dict | None]:
out = self.net(batch["observation.state"])
return out.mean(), None
def predict_action_chunk(self, batch: dict[str, Tensor], **kwargs) -> Tensor:
return self.net(batch["observation.state"])
def select_action(self, batch: dict[str, Tensor], **kwargs) -> Tensor:
return self.net(batch["observation.state"])
def make_dummy_policy(repo_id: str | None = None) -> DummyCheckpointPolicy:
config = DummyCheckpointConfig(device="cpu")
if repo_id is not None:
config.repo_id = repo_id
policy = DummyCheckpointPolicy(config)
with torch.no_grad():
policy.net.weight.fill_(0.5)
return policy