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# Copyright (c) Alibaba, Inc. and its affiliates.
# Part of the implementation is borrowed from huggingface/trl.
import concurrent.futures
import inspect
import os
import re
import time
from collections import defaultdict, deque
from concurrent.futures import Future
from contextlib import contextmanager, nullcontext
from copy import copy, deepcopy
from dataclasses import asdict, dataclass, field
from math import ceil
from queue import Queue
from types import MethodType
from typing import Any, Callable, Dict, List, Optional, Tuple, Union
import torch
import torch.nn as nn
import transformers
from accelerate.utils import broadcast_object_list, gather, gather_object, is_peft_model, set_seed
from packaging import version
from torch.nn import ModuleList
from torch.utils.data import DataLoader
from transformers import PreTrainedModel, TrainerCallback
from transformers.trainer import Trainer
from trl import GRPOTrainer as HFGRPOTrainer
from trl.models import prepare_deepspeed
from trl.trainer.callbacks import SyncRefModelCallback
from trl.trainer.grpo_trainer import RepeatSampler, nanmax, nanmin, nanstd
from trl.trainer.utils import selective_log_softmax
from swift.llm import (InferRequest, MultiModelKeys, RequestConfig, RolloutInferRequest, RowPreprocessor, Template,
get_model_arch, to_device)
from swift.llm.infer.protocol import ChatCompletionResponse
from swift.llm.model.utils import get_llm_model
from swift.llm.template.base import MaxLengthError
from swift.llm.template.template_inputs import StdTemplateInputs
from swift.plugin import multi_turns, orms, rm_plugins
from swift.plugin.multi_turn import MultiTurnScheduler
from swift.utils import (JsonlWriter, empty_cache, get_current_device, get_device, get_logger, is_swanlab_available,
is_vllm_available, is_wandb_available, seed_worker, unwrap_model_for_generation)
from ..mixin import SwiftMixin
from .rlhf_mixin import RLHFTrainerMixin
from .utils import (_ForwardRedirection, patch_lora_merge, patch_lora_unmerge, patch_profiling_context,
patch_profiling_decorator)
from .vllm_client import VLLMClient
try:
from trl.trainer.utils import entropy_from_logits
except ImportError:
from .utils import entropy_from_logits
del HFGRPOTrainer.__init__
del HFGRPOTrainer.log
logger = get_logger()
if is_wandb_available():
import wandb
if is_swanlab_available():
import swanlab
InputsType = List[Dict[str, Union[torch.Tensor, Any]]]
# tuple: (messages, finish_reason)
OutputsType = List[Tuple[List[Dict], str]]
if not hasattr(RepeatSampler, 'old_len_func'):
origin_len_func = RepeatSampler.__len__
def patched_len(self) -> int:
return (self.num_samples // self.batch_size) * self.batch_size * self.mini_repeat_count * self.repeat_count
RepeatSampler.__len__ = patched_len
RepeatSampler.old_len_func = origin_len_func
class GRPOCallback(TrainerCallback):
def __init__(self, trainer):
self.trainer = trainer
# offload original_modules to cpu, to save memory
def on_train_begin(self, args, state, control, **kwargs):
self.trainer.queue = self.trainer.train_queue
train_dataloader = getattr(state, 'train_dataloader', None) or kwargs.get('train_dataloader')
self.trainer._prefetch(train_dataloader)
@dataclass
class DataCache:
inputs: List[Dict] = field(default_factory=list)
outputs: List[Dict] = field(default_factory=list)
def identity_data_collator(features):
return features
class GRPOTrainer(RLHFTrainerMixin, SwiftMixin, HFGRPOTrainer):
executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
def __init__(self,
model: Optional[Union[PreTrainedModel, nn.Module]] = None,
ref_model: Optional[Union[PreTrainedModel, nn.Module]] = None,
reward_model: Optional[List[Union[PreTrainedModel, nn.Module]]] = None,
reward_funcs: Optional[List[Union[str, Callable]]] = None,
*_args,
**kwargs):
from swift.trainers.rlhf_arguments import GRPOConfig
args: GRPOConfig = kwargs['args']
self.args = args
# for async generate
self.train_queue = Queue()
self.eval_queue = Queue()
self.processing_class = kwargs.get('template').tokenizer
if not isinstance(reward_funcs, list):
reward_funcs = [reward_funcs]
if reward_funcs:
for i, reward_func in enumerate(reward_funcs):
if reward_func in orms:
reward_func_class = orms[reward_func]
reward_func_args = list(inspect.signature(reward_func_class.__init__).parameters)
reward_func_kwargs = {
key: getattr(args, key)
for key in reward_func_args if key not in ['self', 'args', 'kwargs'] and hasattr(args, key)
}
if 'tokenizer' in reward_func_args:
reward_func_kwargs['tokenizer'] = self.processing_class
reward_funcs[i] = reward_func_class(**reward_func_kwargs)
elif not callable(reward_func):
raise ValueError(f'reward_function {reward_func} is not implemented in swift.plugin')
self.reward_funcs = reward_funcs
self.reward_func_names = []
for reward_func in reward_funcs:
if inspect.isfunction(reward_func):
reward_func_name = reward_func.__name__
else:
reward_func_name = reward_func.__class__.__name__
self.reward_func_names.append(reward_func_name)
self.reward_model_plugins = [None] * len(self.reward_funcs)
if reward_model is not None:
reward_template = kwargs.pop('reward_template')
reward_plugins = args.reward_model_plugin
if reward_plugins is None:
reward_plugins = ['default'] * len(reward_model)
assert len(reward_plugins) == len(reward_model), (
f"The number of 'reward_model_plugin' ({len(reward_plugins)}) does not match "
f"the number of 'reward_model' ({len(reward_model)}). "
"Please provide a corresponding 'reward_model_plugin' for each 'reward_model'.")
for rm, rm_plugin, rm_template in zip(reward_model, reward_plugins, reward_template):
# Set encoding mode train(see details in Template.encode).
# Set max_length to None to disable truncation, as the input length has already been truncated earlier.
rm_template.set_mode('train')
rm_template.max_length = None
if rm_plugin not in rm_plugins:
raise ValueError(f'rm_plugin {rm_plugin} is not implemented in swift.llm.plugin')
self.reward_model_plugins.append(rm_plugins[rm_plugin](model=rm, template=rm_template))
self.reward_funcs.append(rm)
self.reward_func_names.append(rm.config._name_or_path.split('/')[-1])
self.multi_turn_scheduler = None
if self.args.multi_turn_scheduler:
if isinstance(self.args.multi_turn_scheduler, str):
assert self.args.multi_turn_scheduler in multi_turns
multi_turn_scheduler = multi_turns[self.args.multi_turn_scheduler](max_turns=self.args.max_turns)
self.multi_turn_scheduler: MultiTurnScheduler = multi_turn_scheduler
else:
assert isinstance(multi_turn_scheduler, MultiTurnScheduler)
self.multi_turn_scheduler: MultiTurnScheduler = self.args.multi_turn_scheduler
self.num_generations = args.num_generations
self.temperature = args.temperature
self.vllm_mode = args.vllm_mode
self.vllm_gpu_memory_utilization = args.vllm_gpu_memory_utilization # only applies to colocation mode
self.vllm_tensor_parallel_size = args.vllm_tensor_parallel_size # only applies to colocation mode
self.loss_type = args.loss_type
self.max_completion_length = args.max_completion_length
self.completion_length_limit_scope = args.completion_length_limit_scope
model.warnings_issued['estimate_tokens'] = True
kwargs['data_collator'] = identity_data_collator # No data collation is needed in GRPO
self.shuffle_dataset = args.dataset_shuffle
self.use_vllm = args.use_vllm
self.async_generate = args.async_generate
vllm_client = kwargs.pop('vllm_client') # for external vllm
super().__init__(model, ref_model, *_args, **kwargs)
if self.args.eval_strategy != 'no':
total_eval_batch_size = self.args.per_device_eval_batch_size * \
self.accelerator.num_processes // self.args.num_generations
assert len(self.eval_dataset) >= total_eval_batch_size, (
f'eval_dataset size {len(self.eval_dataset)} is smaller than '
f'total_eval_batch_size {total_eval_batch_size}. '
f'Please increase the size of eval_dataset or set a larger value for split_dataset_ratio.')
# Multi-step
self.num_iterations = args.num_iterations # = 𝜇 in the GRPO paper
self.epsilon_low = args.epsilon
self.epsilon_high = args.epsilon_high if args.epsilon_high is not None else args.epsilon
self.top_entropy_quantile = args.top_entropy_quantile
self.importance_sampling_level = args.importance_sampling_level
self.use_liger_loss = self.args.use_liger_kernel
if self.use_liger_loss:
from liger_kernel.chunked_loss import LigerFusedLinearGRPOLoss
self.liger_grpo_loss = LigerFusedLinearGRPOLoss(
beta=self.beta,
epsilon_low=self.epsilon_low,
epsilon_high=self.epsilon_high,
temperature=self.temperature,
use_ref_model=self.beta != 0.0,
loss_type=self.loss_type,
max_completion_length=self.max_completion_length,
)
self._forward_redirection = _ForwardRedirection()
self._metrics = {'train': defaultdict(list), 'eval': defaultdict(list)}
self.log_completions = args.log_completions
self.wandb_log_unique_prompts = args.wandb_log_unique_prompts
self.num_completions_to_print = args.num_completions_to_print
self.jsonl_writer = JsonlWriter(os.path.join(self.args.output_dir, 'completions.jsonl'))
self._textual_logs = {
'prompt': deque(maxlen=args.generation_batch_size),
'completion': deque(maxlen=args.generation_batch_size),
'rewards': defaultdict(lambda: deque(maxlen=args.generation_batch_size)),
}
self.compute_entropy = self.args.log_entropy or self.top_entropy_quantile < 1.0
if self.args.log_entropy:
self._textual_logs.update({'entropy': deque(maxlen=args.generation_batch_size)})
# Ensure each process receives a unique seed to prevent duplicate completions when generating with
# transformers if num_generations exceeds per_device_train_batch_size. We could skip it if we use vLLM, but
# it's safer to set it in all cases.
set_seed(args.seed, device_specific=True)
if is_peft_model(self.model):
self.parameter_groups, self.parameter_groups_no_lora = self.split_batches()
self.use_fast_infer = self.use_vllm # whether to use the PT backend
self.vllm_use_async_engine = False
self.enable_offload = False
# gym engine
self.use_gym_env = False
if self.use_vllm:
if not is_vllm_available():
raise ImportError('vLLM is not available and `use_vllm` is set to True. '
'Please install vLLM with `pip install vllm -U` to use it.')
if self.vllm_mode == 'server':
self.vllm_client: VLLMClient = vllm_client
if self.accelerator.is_main_process:
vllm_use_async_engine = [self.vllm_client.get_engine_type() == 'AsyncLLMEngine']
use_gym_env = [self.vllm_client.use_gym_env]
else:
vllm_use_async_engine = [False]
use_gym_env = [False]
self.vllm_use_async_engine = broadcast_object_list(vllm_use_async_engine, from_process=0)[0]
self.use_gym_env = broadcast_object_list(use_gym_env, from_process=0)[0]
if self.use_gym_env:
self._textual_logs['trajactory_info'] = deque(maxlen=args.generation_batch_size)
self.reward_func_names = ['gym_reward']
elif self.vllm_mode == 'colocate':
if not self.accelerator.num_processes % self.vllm_tensor_parallel_size == 0:
raise ValueError(
f'vllm_tensor_parallel_size ({self.vllm_tensor_parallel_size}) must divide world size '
f'({self.accelerator.num_processes}) evenly.')
if self.vllm_tensor_parallel_size > 1:
# Create subgroups of ranks for TP, each group with `vllm_tensor_parallel_size` ranks.
# For example, if world_size=8 and vllm_tensor_parallel_size=2 → groups: [0,1], [2,3], [4,5], [6,7]
self.tp_group, _ = torch.distributed.new_subgroups_by_enumeration([
list(range(i * self.vllm_tensor_parallel_size, (i + 1) * self.vllm_tensor_parallel_size))
for i in range(self.accelerator.num_processes // self.vllm_tensor_parallel_size)
])
self.enable_offload = self.args.offload_model or self.args.offload_optimizer
context = self.offload_context if self.enable_offload else nullcontext
with context():
self.engine = self.prepare_vllm(model)
if self.args.sleep_level > 0:
self.engine.engine.sleep(self.args.sleep_level)
else:
from swift.llm import PtEngine
self.engine = PtEngine.from_model_template(self.model, self.template, max_batch_size=0) # 0: no limit
if not self.reward_funcs and not self.use_gym_env:
raise ValueError('You must specify reward_funcs or reward_model')
# Reward weights
if args.reward_weights is not None:
if len(args.reward_weights) != len(reward_funcs):
raise ValueError(f'Number of reward weights ({len(args.reward_weights)}) must match number of reward '
f'functions ({len(reward_funcs)})')
self.reward_weights = torch.tensor(args.reward_weights, dtype=torch.float32)
else:
self.reward_weights = torch.ones(len(reward_funcs), dtype=torch.float32)
self._last_loaded_step = -1 # tag to avoid useless loading during grad accumulation
self.request_config = RequestConfig(
n=1,
max_tokens=args.max_completion_length,
temperature=args.temperature,
top_p=args.top_p,
top_k=args.top_k,
repetition_penalty=args.repetition_penalty,
stop=args.stop_words,
)
# Gradient accumulation requires scaled loss. Normally, loss scaling in the parent class depends on whether the
# model accepts loss-related kwargs. Since we compute our own loss, this check is irrelevant. We set
# self.model_accepts_loss_kwargs to False to enable scaling.
self.model_accepts_loss_kwargs = False
self.padding_free = self.template.padding_free
self.template.padding_free = False
self.template._packing = False
for i, reward_func in enumerate(self.reward_funcs):
if isinstance(reward_func, PreTrainedModel):
if self.is_deepspeed_enabled:
self.reward_funcs[i] = prepare_deepspeed(reward_func, self.accelerator)
else:
self.reward_funcs[i] = self.accelerator.prepare_model(
reward_func, evaluation_mode=True, device_placement=True)
# Tracks the number of iterations (forward + backward passes), including those within a gradient accumulation cycle. # noqa
self._step = 0
# Buffer the batch to reuse generated outputs across multiple updates. For more details, see
# `_get_train_sampler` and `_prepare_inputs`.
self._buffered_inputs = None
if args.sync_ref_model:
self.add_callback(SyncRefModelCallback(ref_model=self.ref_model, accelerator=self.accelerator))
if self.async_generate:
self.add_callback(GRPOCallback(self))
if self.args.dynamic_sample or self.template.truncation_strategy == 'raise':
self.resample_dataset = deepcopy(self.train_dataset)
def cyclic_iter(iterable):
while True:
for x in iterable:
yield x
@contextmanager
def seed_context():
# Use a different seed to ensure the resample dataset does not overlap with train_dataset
seed = self.args.seed
self.args.seed = seed + 1
yield
self.args.seed = seed
with seed_context():
if self.args.dynamic_sample:
self.dynamic_resample_iterator = cyclic_iter(self.get_train_dataloader())
if self.template.truncation_strategy == 'raise':
@contextmanager
def single_sample_context():
# Patch generation-related parameters to ensure that only one sample is processed per iteration
# when resampling truncated data.
origin_ng = self.num_generations
origin_gbs = self.args.generation_batch_size
origin_spg = self.args.steps_per_generation
try:
self.num_generations = 1
self.args.generation_batch_size = 1
self.args.steps_per_generation = 1
yield
finally:
self.num_generations = origin_ng
self.args.generation_batch_size = origin_gbs
self.args.steps_per_generation = origin_spg
with single_sample_context():
self.truncated_resample_iterator = cyclic_iter(self.get_train_dataloader())
# flag indicating whether the evaluation has started
self.eval_flag = False
@patch_profiling_decorator
def _prepare_inputs(self, generation_batch: dict[str, Union[torch.Tensor,
Any]]) -> dict[str, Union[torch.Tensor, Any]]:
# Prepares inputs for model training/evaluation by managing completion generation and batch handling.
# During training:
# - Receives the local generation batch (Per-GPU batch size × steps per generation)
# from the modified training dataloader instead of the standard local batch
# - Generates completions once for the entire generation batch and splits it into batches of size
# `per_device_train_batch_size`
# - Buffers these completions and returns the appropriate slice for the current accumulation step
# - Optimizes by regenerating completions only periodically (every steps_per_generation * num_iterations)
# During evaluation:
# - The input is treated as a standard local batch (no accumulation, no multiple iterations)
# - Completions are generated for each batch without buffering or reuse
# Returns a single local batch in both cases.
mode = 'train' if self.model.training else 'eval'
if mode == 'train':
generate_every = self.args.steps_per_generation * self.num_iterations
if self._step % generate_every == 0 or self._buffered_inputs is None:
generation_batch = self._generate_and_score_completions(generation_batch)
self._buffered_inputs = generation_batch # < this is the change
inputs = self._buffered_inputs[self._step % self.args.steps_per_generation]
self._step += 1
else:
inputs = self._generate_and_score_completions(generation_batch)
return inputs
def split_batches(self):
"""Sync weights in batches
Only split LLM layers for now:
1. N batches for layers
2. other, embeds, lm_heads in one batch
3. multi-modal components in one batch
"""
model = self.accelerator.unwrap_model(self.model)
if self.args.move_model_batches is None:
# All in one
return [[n for n, p in model.named_parameters() if 'ref_model' not in n]], [None]
model_arch = get_model_arch(model.model_meta.model_arch)
non_llm_parameters = []
llm_embeds = []
parameters = []
pattern = r'\.(\d+)\.'
layer_count = None
# Get the number of layers in LLM modules
for name, module in model.named_modules():
if isinstance(module, ModuleList):
if model_arch is not None and isinstance(model_arch, MultiModelKeys):
llm = model_arch.language_model
vision_tower = model_arch.vision_tower
if any(vt in name for vt in vision_tower):
continue
if isinstance(llm, list):
llm = llm[0]
if name.startswith('base_model'):
name = name.replace('base_model.', '')
if llm in name:
layer_count = len(module)
else:
layer_count = len(module)
assert layer_count is not None, 'Cannot find ModuleList to split modules.'
n_layers = ceil(layer_count / self.args.move_model_batches)
for _ in range(self.args.move_model_batches):
parameters.append([])
def replace_lora(name):
if 'lora_' in name:
return ''
else:
return name.replace('base_layer.', '')
def remove_lora_and_prefix(names):
names = set([re.sub(r'^_model\.', '', replace_lora(n)) for n in names])
return [n for n in names if n]
def split_llm(name):
match = re.search(pattern, name)
if match:
number = match.group(1)
group = int(number) // n_layers
parameters[group].append(name)
else:
llm_embeds.append(name)
for name, parameter in model.named_parameters():
if 'ref_model' in name:
continue
if model_arch is not None and isinstance(model_arch, MultiModelKeys):
llm = model_arch.language_model
vision_tower = model_arch.vision_tower
if any(vt in name for vt in vision_tower):
non_llm_parameters.append(name)
elif isinstance(llm, list):
llm = llm[0]
if llm in name:
split_llm(name)
else:
non_llm_parameters.append(name)
else:
split_llm(name)
if llm_embeds:
parameters.append(llm_embeds)
if non_llm_parameters:
parameters.append(non_llm_parameters)
parameters = [p for p in parameters if p]
parameters_no_lora = [remove_lora_and_prefix(p_list) for p_list in parameters]
return parameters, parameters_no_lora
def prepare_vllm(self, model):
from swift.tuners import Swift
from swift.llm.infer.infer_engine import GRPOVllmEngine
max_num_seqs = (
self.args.per_device_train_batch_size * self.vllm_tensor_parallel_size * self.args.steps_per_generation)
current_device = get_device()
with Swift.grpo_context(model, self.template.processor):
engine = GRPOVllmEngine(
model.model_dir,
model.model_info.torch_dtype,
model_type=model.model_meta.model_type,
use_async_engine=False, # TODO: async engine for colocate
tensor_parallel_size=self.vllm_tensor_parallel_size,
gpu_memory_utilization=self.vllm_gpu_memory_utilization,
enable_prefix_caching=self.args.vllm_enable_prefix_caching,
max_num_seqs=max_num_seqs,
enforce_eager=self.args.vllm_enforce_eager,
limit_mm_per_prompt=self.args.vllm_limit_mm_per_prompt,
enable_sleep_mode=self.args.sleep_level > 0,
device=current_device,
max_model_len=self.args.vllm_max_model_len,
seed=self.accelerator.process_index // self.vllm_tensor_parallel_size,
template=self.template,
distributed_executor_backend='external_launcher',
)
return engine
@contextmanager
def _template_context(self, template: Template):
# The max_length for prompt and completion has already been restricted, so there is no need for max_length here.
max_length = template.max_length
mode = template.mode
if mode in {'vllm', 'pt', 'lmdeploy'}:
template.set_mode('train')
template.max_length = None
try:
yield
finally:
template.set_mode(mode)
template.max_length = max_length
@patch_profiling_decorator
def _move_model_to_vllm(self, skip_async_check=False):
deepspeed_plugin = self.accelerator.state.deepspeed_plugin
zero_stage_3 = deepspeed_plugin is not None and deepspeed_plugin.zero_stage == 3
if zero_stage_3:
import deepspeed
gather_if_zero3 = deepspeed.zero.GatheredParameters
else:
gather_if_zero3 = nullcontext
if self.args.async_generate and not skip_async_check:
# before sync weight, we should wait async generate finish
self._wait_queue()
if is_peft_model(self.model):
for i, parameter_group in enumerate(self.parameter_groups): # < this is the change
parameter_group_no_lora = self.parameter_groups_no_lora[i]
parameters = [
parameter for name, parameter in self.model.named_parameters()
if not parameter_group or name in parameter_group
]
with gather_if_zero3(parameters), patch_lora_merge(self.model, parameter_group):
self.model.merge_adapter()
state_dict = self.model.state_dict()
state_dict = {
k.removeprefix('base_model.model.').replace('.base_layer', ''): v
for k, v in state_dict.items()
}
state_dict = {k: v for k, v in state_dict.items() if self.model.prefix not in k}
# When module to save, remove its prefix and discard the original module
state_dict = {
k.replace('modules_to_save.default.', ''): v
for k, v in state_dict.items() if 'original_module' not in k
}
if parameter_group_no_lora:
parameter_group_no_lora = [n.replace('base_model.model.', '') for n in parameter_group_no_lora]
state_dict = {k: v for k, v in state_dict.items() if k in parameter_group_no_lora}
assert len(state_dict) > 0 and all(
[state.shape != torch.Size([0]) for state in state_dict.values()])
if self.vllm_mode == 'server' and self.accelerator.is_main_process:
for name, param in state_dict.items():
self.vllm_client.update_named_param(name, param)
elif self.vllm_mode == 'colocate':
llm_model = self.engine.inner_model
llm_model.load_weights(state_dict.items())
with patch_lora_unmerge(self.model):
self.model.unmerge_adapter()
del state_dict
else:
for name, param in self.model.named_parameters():
with gather_if_zero3([param]):
if self.vllm_mode == 'server' and self.accelerator.is_main_process:
self.vllm_client.update_named_param(name, param.data)
elif self.vllm_mode == 'colocate':
llm_model = self.engine.inner_model
llm_model.load_weights([(name, param.data)])
if self.vllm_mode == 'server' and self.accelerator.is_main_process:
self.vllm_client.reset_prefix_cache()
elif self.vllm_mode == 'colocate':
# since vLLM model weights has been updated, we should reset the prefix cache
self.engine.engine.reset_prefix_cache()
def _wait_queue(self):
while self._queue.empty():
time.sleep(0.01)
def _infer(self,
inputs: Optional[InputsType],
request_config: RequestConfig,
is_global_inputs: bool = False) -> List[ChatCompletionResponse]:
request_config = self._get_request_config()
# keys from InferRequest
per_device_size = len(inputs)
if is_global_inputs:
per_device_size //= self.accelerator.num_processes
if self.vllm_mode == 'server':
# for server mode, we gather all the inputs and send to remote vllm server in main process
if is_global_inputs:
# async generate, pre-gather to avoid potential communicate operator
all_inputs = inputs
all_input_lengths = [per_device_size] + [0] * (self.accelerator.num_processes - 1)
else:
all_inputs = gather_object(inputs)
all_input_lengths = gather_object([len(inputs)])
if not any(inputs for inputs in all_inputs):
return []
if self.accelerator.is_main_process:
results: List[ChatCompletionResponse] = self._engine_infer(
infer_requests=all_inputs, request_config=request_config)
else:
results = [None] * len(all_inputs)
# Broadcast the results from the main process to all processes,
# ensuring each process receives its corresponding slice.
if not is_global_inputs:
results = broadcast_object_list(results, from_process=0)
start_idx = sum(all_input_lengths[:self.accelerator.process_index])
end_idx = start_idx + all_input_lengths[self.accelerator.process_index]
results = results[start_idx:end_idx]
else:
results = results if self.accelerator.is_main_process else []
else:
# pt / vllm colocate
if self.vllm_tensor_parallel_size > 1:
# Gather prompts from all ranks in the TP group and flatten.
# Each rank starts with its own prompts; after gathering, all ranks see the full group set.
# Note: The input sizes may differ across ranks (e.g., in multi-turn scenarios,
# the amount of data each rank continues to process may vary).
local_rank_in_group = torch.distributed.get_rank(group=self.tp_group)
local_input_length = len(inputs)
all_input_lengths = [None] * self.vllm_tensor_parallel_size
torch.distributed.all_gather_object(all_input_lengths, local_input_length, group=self.tp_group)
start_idx = sum(all_input_lengths[:local_rank_in_group])
end_idx = start_idx + all_input_lengths[local_rank_in_group]
# orig_size = len(inputs)/
gathered_inputs = [None for _ in range(self.vllm_tensor_parallel_size)]
torch.distributed.all_gather_object(gathered_inputs, inputs, group=self.tp_group)
inputs = [p for sublist in gathered_inputs for p in sublist]
# Set request_config.seed
# 1. Ensure that the seed for vLLM Engines within each TP (Tensor Parallelism) group is the same;
# otherwise, the program may hang.
# 2. Ensure that the seed for vLLM Engines across different TP groups is different;
# otherwise, identical completions will be generated.
results: List[ChatCompletionResponse] = self._engine_infer(
infer_requests=inputs, request_config=request_config)
if self.vllm_tensor_parallel_size > 1:
# Slice completions for this rank within its TP group.
# Each rank generates all outputs — we keep only our share.
results = results[start_idx:end_idx]
return results
def _get_request_config(self) -> RequestConfig:
request_config = copy(self.request_config)
if self.args.vllm_mode == 'colocate' and self.vllm_tensor_parallel_size > 1:
# Set request_config.seed
# 1. Ensure that the seed for vLLM Engines within each TP (Tensor Parallelism) group is the same;
# otherwise, the program may hang.
# 2. Ensure that the seed for vLLM Engines across different TP groups is different;
# otherwise, identical completions will be generated.
mode = 'train' if self.model.training else 'eval'
batch_size = (
self.args.per_device_train_batch_size
* self.args.gradient_accumulation_steps if mode == 'train' else self.args.per_device_eval_batch_size)
batch_size *= self.vllm_tensor_parallel_size
# Since the TP (Tensor Parallelism) group gathers the inputs,
# multiply the batch size by the TP parallel size.
request_config.seed = batch_size * (self.accelerator.process_index // self.vllm_tensor_parallel_size)
return request_config
def _set_inputs_system(self, inputs: InputsType) -> InputsType:
if not self.template.template_meta.default_system:
return
if all(_input['messages'][0]['role'] == 'system' for _input in inputs):
return
for _input in inputs:
messages = _input['messages']
if messages[0]['role'] != 'system':
messages.insert(0, {'role': 'system', 'content': self.template.template_meta.default_system})
def _infer_single_or_multi_turn(self,
inputs: InputsType,
request_config: RequestConfig,
is_global_inputs: bool = False) -> OutputsType:
"""Perform multi-turn or single-turn inference
Args:
inputs: list of input requests
request_config: Inference configuration parameters
is_global_inputs:
A boolean indicating whether the inputs are global. When set to True,
the returned results in the main process will be a complete list of
global_outputs, while other processes will return an empty list [].
Returns:
List of outputs where each entry contains:
- List of responses per prompt
- Each response is a tuple of (message_history, finish_reason)
"""
self._set_inputs_system(inputs)
# infer first turn
results: List[ChatCompletionResponse] = self._infer(inputs, request_config, is_global_inputs)
outputs = []
if not self.multi_turn_scheduler and not self.vllm_use_async_engine:
# message concatenation
for i, output in enumerate(results):
_choices = []
for choice in output.choices:
_input: Dict = deepcopy(inputs[i])
InferRequest.remove_response(_input['messages'])
_input['messages'].append({'role': 'assistant', 'content': choice.message.content})
_choices.append((_input['messages'], choice.finish_reason, {}))
outputs.append(_choices)
outputs = [item for sublist in outputs for item in sublist]
else:
# vLLMAsyncLLMEngine, only server mode is supported right now.
# NOTE: The message concatenation has already been done in the engine.
if self.vllm_use_async_engine:
for i, output in enumerate(results):
_choices = []
for choice in output.choices:
# concated in Engine
if self.use_gym_env:
_choices.append(
(choice.messages, choice.finish_reason, choice.total_reward, choice.trajectory_info))
else:
_choices.append((choice.messages, choice.finish_reason))
outputs.append(_choices)
outputs = [item for sublist in outputs for item in sublist]
else:
# PTEngine or vLLMLLMEngine
orig_size = len(inputs)
outputs = [None] * orig_size
# we remove origin response in first turn
current_turn = 1
while True:
has_local_data = len(inputs) > 0
has_global_data = gather_object([has_local_data])
if not any(has_global_data):
break
# inputs for current turn
current_inputs = []
cnt = 0
# combine completions from results with messages
for i, output in enumerate(results):
for choice in output.choices:
current_input = deepcopy(inputs[i])
messages = current_input['messages']
if current_turn == 1 or not messages[-1]['content'] or messages[-1]['content'] == '<None>':
# first turn or the last message content is empty(dummy), remove the response
InferRequest.remove_response(messages)
if messages[-1]['role'] == 'assistant':
# If the last message was assistant, concatenate the new content to it
messages[-1]['content'] += choice.message.content
else:
# append a new message from the assistant
messages.append({'role': 'assistant', 'content': choice.message.content})
if 'index' not in current_input:
current_input['index'] = cnt
current_input['finish_reason'] = choice.finish_reason
cnt += 1
current_inputs.append(current_input)
# Process messages in the multi-turn function
should_stops = [
self.multi_turn_scheduler.check_finished(request, result.choices[0], current_turn)
for request, result in zip(self.inputs_to_rolloutrequest(current_inputs), results)
]
# Retain messages that are not yet finished for the next round of rollout
pending_inputs = []
for stop, _input, result in zip(should_stops, current_inputs, results):
index = _input['index']
if stop:
outputs[index] = (_input['messages'], _input['finish_reason'],
_input.get('multi_turn_infos', {'num_turns': 1}))
else:
current_request = self.inputs_to_rolloutrequest([_input])[0]
ret = self.multi_turn_scheduler.step(current_request, result.choices[0], current_turn)
if isinstance(ret, tuple):
infer_request, info_dict = ret
else:
infer_request = ret
info_dict = {}
info_dict['num_turns'] = current_turn + 1
pending_input = asdict(infer_request)
if 'multi_turn_infos' not in pending_input:
pending_input['multi_turn_infos'] = {}
for key, value in info_dict.items():
pending_input['multi_turn_infos'][key] = value
pending_input['index'] = index
pending_inputs.append(pending_input)
current_infer_inputs = pending_inputs if has_local_data else []
results = self._infer(current_infer_inputs, request_config)
inputs = pending_inputs
current_turn += 1
assert not any([o is None for o in outputs])
# flatten 2D list to 1D list
return outputs
def async_infer(self, all_inputs):
current_queue = self._queue
def infer_task():
try:
with self.multi_turn_completion_length_context():
return self._infer_single_or_multi_turn(all_inputs, self.request_config, is_global_inputs=True)
except Exception as e:
logger.error('Inference task failed: %s', str(e))
raise
future: Future = self.executor.submit(infer_task)
# pre-fetch the queue to avoid switching back to eval_queue at the end of training sample sampling
def done(future):
try:
result = future.result()
current_queue.put(DataCache(all_inputs, result))
except Exception as e:
logger.error('Error in async_infer callback: %s', str(e))
future.add_done_callback(done)
def _prefetch(self, dataloader: DataLoader):
inputs = next(iter(dataloader))
all_inputs = gather_object(inputs)
if self.state.global_step != self._last_loaded_step:
self._move_model_to_vllm(skip_async_check=True)
self._last_loaded_step = self.state.global_step
outputs = self._infer_single_or_multi_turn(all_inputs, self.request_config, is_global_inputs=True)
self._queue.put(DataCache(all_inputs, outputs))
def _fast_infer(self, inputs: InputsType) -> Tuple[InputsType, OutputsType]:
# Skip the first wake_up to avoid the warning "Executor is not sleeping"
if self.vllm_mode == 'colocate' and self.args.sleep_level > 0:
if self.engine.inner_model_executor.is_sleeping:
# First, load weights only, https://github.com/vllm-project/vllm/pull/15500
if 'tags' in inspect.signature(self.engine.engine.wake_up).parameters:
self.engine.engine.wake_up(tags=['weights'])
else:
logger.info('We recommend installing vLLM >= 0.8.3, (ideally 0.8.5.post1)'
'to help reduce memory peaks during engine wake-up.')
self.engine.engine.wake_up()
# First, have main process load weights if needed
if self.state.global_step != self._last_loaded_step:
self._move_model_to_vllm()
self._last_loaded_step = self.state.global_step
context = self.offload_context if self.enable_offload else nullcontext
with context():
if self.vllm_mode == 'colocate' and self.engine.inner_model_executor.is_sleeping and \
'tags' in inspect.signature(self.engine.engine.wake_up).parameters:
# Load the kv_cache only after updating and offload the weights.
self.engine.engine.wake_up(tags=['kv_cache'])
if self.async_generate:
# send this step data to server
# we gather inputs outside the thread for prevent potential gather deadlock
all_inputs = gather_object(inputs)
self.async_infer(all_inputs)
# cached data from last step
data_cache = self._queue.get()
all_inputs = data_cache.inputs
all_outputs = gather_object(data_cache.outputs)
process_slice = slice(
self.accelerator.process_index * len(inputs),
(self.accelerator.process_index + 1) * len(inputs),
)
inputs = all_inputs[process_slice]
outputs = all_outputs[process_slice]
else:
with self.multi_turn_completion_length_context():
outputs = self._infer_single_or_multi_turn(inputs, self.request_config)
if self.vllm_mode == 'colocate' and self.args.sleep_level > 0:
# Reset prefix cache before sleeping to prevent using stale cache upon waking up
# https://github.com/modelscope/ms-swift/pull/5143
self.engine.engine.reset_prefix_cache()
self.engine.engine.sleep(level=self.args.sleep_level)
empty_cache()
return inputs, outputs
def _generate_completions(self, inputs: InputsType) -> InputsType:
"""Generate completions for given inputs using either fast inference or standard PyTorch inference.
Args:
inputs: List of input examples containing conversation messages.
Returns:
Modified inputs with generated completions added to the last message
and truncation flag set in 'is_truncated' field.
"""
mode = 'train' if self.model.training else 'eval'
if self.use_fast_infer:
inputs, outputs = self._fast_infer(inputs)
else:
with unwrap_model_for_generation(
self.model_wrapped, self.accelerator, gather_deepspeed3_params=self.args.ds3_gather_for_generation
), self.template.generate_context(), self.multi_turn_completion_length_context():
outputs = self._infer_single_or_multi_turn(inputs, self.request_config)
if mode == 'train':
# In training mode, ensure the model is returned to train() mode after inference
# This is necessary as pt engines set the model to eval mode during generation
self.model.train()
for i, output in enumerate(outputs):
inputs[i]['messages'] = output[0]
inputs[i]['is_truncated'] = output[1] == 'length'
multi_turn_infos = output[2] if len(output) > 2 else {}
if 'images' in multi_turn_infos:
# override images
inputs[i]['images'] = multi_turn_infos['images']
inputs[i]['multi_turn_infos'] = multi_turn_infos
if self.use_gym_env:
inputs[i]['total_reward'] = output[2]
inputs[i]['trajectory_info'] = output[3]
return inputs
def _generate_and_score_completions(self, inputs: InputsType) -> InputsType:
if self.template.truncation_strategy == 'raise':
inputs = self.resample_truncated_inputs(inputs)
inputs = self._generate_completions(inputs)
total_rewards_per_func, total_rewards, completions = self._score_completions(inputs)
mode = 'train' if self.model.training else 'eval'
if self.args.dynamic_sample and mode == 'train':
# dynamic sampling for std=0 groups
inputs, total_rewards, total_rewards_per_func, completions = \
self._dynamic_sampling(inputs, total_rewards, total_rewards_per_func, completions)
# Prepare final outputs with advantages and other required fields
batch_encoded_inputs = self._prepare_batch_inputs(inputs, total_rewards)
# Log metrics
messages = [inputs[i]['messages'][:-1] for i in range(len(inputs))]
trajactory_infos = None
if self.use_gym_env:
trajactory_infos = [inputs[i]['trajectory_info'] for i in range(len(inputs))]
self._log_metrics(batch_encoded_inputs, messages, completions, total_rewards, total_rewards_per_func,
trajactory_infos)
return batch_encoded_inputs
def _score_completions(self, inputs: InputsType) -> Tuple[torch.Tensor, torch.Tensor, List[str]]:
"""Score completions using all reward functions
Args:
inputs: List of input examples, each containing a 'messages' list with conversation history
Returns:
Tuple containing:
- rewards_per_func: Tensor of shape (num_examples, num_reward_funcs) with individual rewards
- total_rewards: Tensor of shape (num_examples,) with weighted sum of rewards
- completions: List of generated completion strings
"""
device = self.accelerator.device
completions = [example['messages'][-1]['content'] for example in inputs]
# If using gym environment, extract rewards directly from inputs
if self.use_gym_env:
total_rewards = torch.tensor([inp['total_reward'] for inp in inputs], dtype=torch.float32, device=device)
# For gym environment, there's only one total reward, so rewards_per_func is just total_rewards reshaped
rewards_per_func = total_rewards.unsqueeze(1) # shape: [num_examples, 1]
total_rewards_per_func = gather(rewards_per_func)
total_rewards_gathered = total_rewards_per_func.squeeze(1) # Recover from gathered data
return total_rewards_per_func, total_rewards_gathered, completions
rewards_per_func = torch.zeros((len(inputs), len(self.reward_funcs)), device=device)
for i, (reward_func, reward_model_plugin, reward_func_name) in enumerate(
zip(self.reward_funcs, self.reward_model_plugins, self.reward_func_names)):
with patch_profiling_context(self, reward_func_name):
# reward model
if isinstance(reward_func, nn.Module):
output_reward_func = reward_model_plugin(inputs=inputs)
# reward function
else:
# Repeat all input columns (but "messages" and "completion") to match the number of generations
reward_kwargs = RowPreprocessor.rows_to_batched(inputs)
reward_kwargs['trainer_state'] = self.state
output_reward_func = reward_func(completions, **reward_kwargs)
output_reward_func = [reward if reward is not None else torch.nan for reward in output_reward_func]
rewards_per_func[:, i] = torch.tensor(output_reward_func, dtype=torch.float32, device=device)
# If all reward functions return None for a given row, issue a detailed warning
if torch.isnan(rewards_per_func).all(dim=1).any():
nan_row_idx = torch.isnan(rewards_per_func).all(dim=1).nonzero(as_tuple=True)[0][0]
row_reward_kwargs = {key: value[nan_row_idx] for key, value in reward_kwargs.items()}
row_reward_kwargs['completion'] = completions[nan_row_idx]
logger.warning(f'All reward functions returned None for the following kwargs: {row_reward_kwargs}. '
'Please ensure that at least one reward function returns a valid reward.')
total_rewards_per_func = gather(rewards_per_func)
total_rewards = (total_rewards_per_func * self.reward_weights.to(device).unsqueeze(0)).nansum(dim=1)
return total_rewards_per_func, total_rewards, completions
def _dynamic_sampling(self, inputs, rewards, rewards_per_func, completions):
# DAPO https://arxiv.org/abs/2503.14476
# Replaces samples with zero-reward-variance groups (std=0)
resample_count = 0
valid_samples = []
valid_rewards = []
valid_rewards_per_func = []
valid_completions = []
origin_data = (inputs, rewards, rewards_per_func, completions)
while resample_count < self.args.max_resample_times:
grouped_rewards = rewards.view(-1, self.num_generations)
group_std = grouped_rewards.std(dim=1)
valid_mask = (group_std > 0).repeat_interleave(self.num_generations)
all_inputs = gather_object(inputs)
valid_samples.extend([inp for inp, mask in zip(all_inputs, valid_mask) if mask])
valid_rewards.append(rewards[valid_mask])
valid_rewards_per_func.append(rewards_per_func[valid_mask])
valid_completions.extend(
[inp['messages'][-1]['content'] for inp, mask in zip(all_inputs, valid_mask) if mask])
if len(valid_samples) >= self.args.generation_batch_size:
break
inputs = next(self.dynamic_resample_iterator)
inputs = Trainer._prepare_inputs(self, inputs)
inputs = self._generate_completions(inputs)
rewards_per_func, rewards, completions = self._score_completions(inputs)
resample_count += 1
if len(valid_samples) >= self.args.generation_batch_size:
process_slice = slice(
self.accelerator.process_index * len(inputs),
(self.accelerator.process_index + 1) * len(inputs),
)
inputs = valid_samples[:self.args.generation_batch_size][process_slice]
rewards = torch.cat(valid_rewards)[:self.args.generation_batch_size]
rewards_per_func = torch.cat(valid_rewards_per_func)[:self.args.generation_batch_size]
completions = valid_completions[:self.args.generation_batch_size][process_slice]
else:
logger.warning(f'There are still std=0 groups present after {self.args.max_resample_times} retries.')
inputs, rewards, rewards_per_func, completions = origin_data
return inputs, rewards, rewards_per_func, completions
def split_by_mini_batches(self, inputs, advantages):
# Slice to keep only the local part of the data
# Slice to keep only the local part of the data
process_slice = slice(
self.accelerator.process_index * len(inputs),
(self.accelerator.process_index + 1) * len(inputs),
)
advantages = advantages[process_slice]
mode = 'train' if self.model.training else 'eval'
bs = self.args.per_device_train_batch_size if mode == 'train' else self.args.per_device_eval_batch_size
spg = self.args.steps_per_generation if mode == 'train' else 1
assert len(inputs) == bs * spg, f'Expected {bs * spg} inputs, got {len(inputs)}'
spg_chunks = [inputs[i * bs:(i + 1) * bs] for i in range(spg)]
# Split advantages by spg chunks
advantage_chunks = torch.chunk(advantages, spg)
return spg_chunks, advantage_chunks
def _prepare_batch_inputs(self, inputs: InputsType, rewards: torch.Tensor) -> List[InputsType]:
"""
Prepare the final batch inputs with advantages, ref/old_policy logps and other fields for RL training.
Args:
inputs (InputsType): List of input samples. Original shape is [spg*bs] where:
- spg: steps_per_generation
- bs: per-device batch size
rewards (torch.Tensor): Tensor of global rewards corresponding to the inputs.
Shape should match the total number of samples (spg*bs*num_processes*num_generations)
Returns:
List[InputsType]: A list of prepared batch inputs, organized as [spg][bs]
"""
# Compute advantages
grouped_rewards = rewards.view(-1, self.num_generations)
mean_grouped_rewards = grouped_rewards.mean(dim=1).repeat_interleave(self.num_generations, dim=0)
std_grouped_rewards = grouped_rewards.std(dim=1).repeat_interleave(self.num_generations, dim=0)
advantages = (rewards - mean_grouped_rewards)
if self.args.scale_rewards:
advantages /= (std_grouped_rewards + 1e-4)
template = self.template
gas_chunks, advantage_chunks = self.split_by_mini_batches(inputs, advantages)
ga_batch_encoded_inputs = []
for i, (batch, batch_advantages) in enumerate(zip(gas_chunks, advantage_chunks)):
# Encode and process each batch (size=bs)
with self._template_context(template):
batch_encoded_inputs = [template.encode(infer_request) for infer_request in batch]
batch_encoded_inputs = to_device(template.data_collator(batch_encoded_inputs), self.model.device)
# Process labels and masks
labels = batch_encoded_inputs.pop('labels')
logits_to_keep = (labels.shape[-1] - (torch.ne(labels, -100).int().argmax(-1))).max().item()
batch_encoded_inputs.update({
'completion_mask':
labels[:, -logits_to_keep:] != -100,
'truncated_mask':
torch.tensor([b['is_truncated'] for b in batch], dtype=torch.bool),
'logits_to_keep':
logits_to_keep,
'advantages':
batch_advantages
})
with torch.no_grad():
batch_encoded_inputs['old_per_token_logps'] = (
self._get_per_token_logps_and_entropies(self.model, batch_encoded_inputs)[0]
if self.old_policy() else None)
ga_batch_encoded_inputs.append(batch_encoded_inputs)
return ga_batch_encoded_inputs
def _log_metrics(self, inputs, messages, completions, rewards, rewards_per_func, trajactory_infos=None):
"""Log training/evaluation metrics"""
mode = 'train' if self.model.training else 'eval'
device = self.accelerator.device
# Calculate completion length metrics
agg_completion_mask = gather(torch.cat([inp['completion_mask'].sum(1) for inp in inputs]))
self._metrics[mode]['completions/mean_length'].append(agg_completion_mask.float().mean().item())
self._metrics[mode]['completions/min_length'].append(agg_completion_mask.float().min().item())
self._metrics[mode]['completions/max_length'].append(agg_completion_mask.float().max().item())
# Calculate clip ratio
agg_truncated_mask = gather(torch.cat([inp['truncated_mask'] for inp in inputs]).to(device))
term_completion_mask = agg_completion_mask[agg_truncated_mask]
clipped_completions_ratio = len(term_completion_mask) / len(agg_completion_mask)
self._metrics[mode]['completions/clipped_ratio'].append(clipped_completions_ratio)
for i, reward_func_name in enumerate(self.reward_func_names):
mean_rewards = torch.nanmean(rewards_per_func[:, i]).item()
self._metrics[mode][f'rewards/{reward_func_name}/mean'].append(mean_rewards)
std_rewards = nanstd(rewards_per_func[:, i]).item()
self._metrics[mode][f'rewards/{reward_func_name}/std'].append(std_rewards)
# Log overall reward stats
grouped_rewards = rewards.view(-1, self.num_generations)
std_grouped_rewards = grouped_rewards.std(dim=1)
is_std_zero = torch.isclose(std_grouped_rewards, torch.zeros_like(std_grouped_rewards))
self._metrics[mode]['reward'].append(grouped_rewards.mean().item())
self._metrics[mode]['reward_std'].append(std_grouped_rewards.mean().item())
self._metrics[mode]['frac_reward_zero_std'].append(is_std_zero.float().mean().item())
# Log prompt and completion texts
self._textual_logs['prompt'].extend(self._apply_chat_template_to_messages_list(gather_object(messages)))
self._textual_logs['completion'].extend(gather_object(completions))
if self.use_gym_env:
self._textual_logs['trajactory_info'].extend(gather_object(trajactory_infos))
for i, name in enumerate(self.reward_func_names):
self._textual_logs['rewards'][name].extend(rewards_per_func[:, i].tolist())
def _apply_chat_template_to_messages_list(self, messages_list: InputsType):
prompts_text = []
for messages in messages_list:
InferRequest.remove_response(messages)
template_inputs, _ = StdTemplateInputs.from_dict({'messages': messages})
res_context_list, _, _ = self.template._swift_encode(template_inputs)
# check the type and convert
processed_context = []
for context in res_context_list:
if isinstance(context, str):
processed_context.append(context)
elif isinstance(context, list) and all(isinstance(x, int) for x in context):
# decode the token ID to text
decoded_text = self.template.tokenizer.decode(context)
processed_context.append(decoded_text)
else:
# other type value ,just add to process_context
processed_context.append(str(context))
prompts_text.append(''.join(processed_context))
return prompts_text
@patch_profiling_decorator
def compute_loss(self, model, inputs, return_outputs=False, num_items_in_batch=None):
# Compute the per-token log probabilities for the model, return_outputs=True in mini-batch training
if isinstance(inputs, list):
assert len(inputs) == 1
inputs = inputs[0]
if self.use_liger_loss:
unwrapped_model = self.accelerator.unwrap_model(model)
return self._forward_redirection(model, unwrapped_model, self.compute_liger_loss, unwrapped_model, inputs)
else:
return self._compute_loss(model, inputs)
def _compute_loss(self, model, inputs):
mode = 'train' if self.model.training else 'eval'
completion_mask = inputs['completion_mask']
truncated_mask = inputs['truncated_mask']
per_token_logps, entropies = self._get_per_token_logps_and_entropies(
model, inputs, compute_entropy=self.compute_entropy)
entropy_mask = None
if self.compute_entropy:
# fill the padded token with NaN
entropies = entropies.masked_fill(completion_mask == 0, float('nan'))
if self.args.log_entropy:
per_completion_entropies_mean = torch.nanmean(entropies, dim=1)
global_per_completion_entropies_mean = gather(per_completion_entropies_mean)
self._textual_logs['entropy'].extend(global_per_completion_entropies_mean.tolist())
self._metrics[mode]['entropy/mean'].append(global_per_completion_entropies_mean.mean().item())
self._metrics[mode]['entropy/max'].append(global_per_completion_entropies_mean.max().item())
self._metrics[mode]['entropy/min'].append(global_per_completion_entropies_mean.min().item())
# compute the entropy threshold across all tokens in the batch
if self.args.top_entropy_quantile < 1.0:
entropy_threshold = torch.nanquantile(entropies.flatten().float(), 1 - self.top_entropy_quantile)
self._metrics[mode]['entropy/threshold'].append(entropy_threshold.item())
entropy_mask = entropies >= entropy_threshold
# apply the completion_mask to exclude loss and metrics for overlong completions
if self.args.overlong_filter and any(truncated_mask):
if all(truncated_mask):
logger.info('All completions are overlong and truncated, '
'resulting in NaN some values for some metrics (e.g., KL)')
truncated_mask = truncated_mask.unsqueeze(-1).expand_as(completion_mask).to(completion_mask.device)
completion_mask = completion_mask * (~truncated_mask)
# Compute the KL divergence between the model and the reference model
if self.beta != 0.0:
with torch.no_grad():
if self.ref_model is not None:
ref_per_token_logps, _ = self._get_per_token_logps_and_entropies(self.ref_model, inputs)
else:
with self.accelerator.unwrap_model(self.model).disable_adapter():
ref_per_token_logps, _ = self._get_per_token_logps_and_entropies(self.model, inputs)
per_token_kl = (
torch.exp(ref_per_token_logps - per_token_logps) - (ref_per_token_logps - per_token_logps) - 1)
advantages = inputs['advantages']
# When under on-policy training
# old_per_token_logps == per_token_logps, so we can skip it's computation
# (see _generate_and_score_completions) and use per_token_logps.detach() instead.
old_per_token_logps = (
per_token_logps.detach() if inputs['old_per_token_logps'] is None else inputs['old_per_token_logps'])
log_ratio = per_token_logps - old_per_token_logps
if self.importance_sampling_level == 'token':
log_importance_weights = log_ratio
elif self.importance_sampling_level == 'sequence':
log_importance_weights = (log_ratio * completion_mask).sum(-1) / completion_mask.sum(-1).clamp(min=1.0)
log_importance_weights = log_importance_weights.unsqueeze(-1)
else:
raise ValueError(
f"Unknown importance sampling level: {self.importance_sampling_level}. Possible values are 'token' "
"and 'sequence'.")
# From here, log_importance_weights (and all subsequent tensors, coef_1, coef_2, etc.) shape depends on
# importance_sampling_level: "token" level: (B, T); "sequence" level: (B, 1)
coef_1 = torch.exp(log_importance_weights)
coef_2 = torch.clamp(coef_1, 1 - self.epsilon_low, 1 + self.epsilon_high)
if self.args.delta is not None:
coef_1 = torch.clamp(coef_1, max=self.args.delta)
per_token_loss1 = coef_1 * advantages.unsqueeze(1)
per_token_loss2 = coef_2 * advantages.unsqueeze(1)
per_token_loss = -torch.min(per_token_loss1, per_token_loss2)
if entropy_mask is not None:
per_token_loss = per_token_loss * entropy_mask
if self.beta != 0.0:
per_token_loss = per_token_loss + self.beta * per_token_kl
if self.loss_type == 'grpo':
loss = ((per_token_loss * completion_mask).sum(-1) / completion_mask.sum(-1).clamp(min=1.0)).mean()
elif self.loss_type == 'bnpo':
loss = (per_token_loss * completion_mask).sum() / completion_mask.sum().clamp(min=1.0)
elif self.loss_type == 'dr_grpo':
loss = (per_token_loss * completion_mask).sum() / (per_token_loss.size(0) * self.max_completion_length)
else:
raise ValueError(f'Unknown loss type: {self.loss_type}')
completion_token_count = completion_mask.sum().clamp(min=1.0)
def masked_batch_mean(x):
if x.shape[1] == 1: # when importance_sampling_level == "sequence"
return x.mean()
else:
return (x * completion_mask).sum() / completion_token_count
if self.beta != 0.0:
mean_kl = masked_batch_mean(per_token_kl)
self._metrics[mode]['kl'].append(self.accelerator.gather_for_metrics(mean_kl).nanmean().item())
# Compute the clipped probability ratios
is_low_clipped = (coef_1 < 1 - self.epsilon_low) & (advantages.unsqueeze(1) < 0)
is_high_clipped = (coef_1 > 1 + self.epsilon_high) & (advantages.unsqueeze(1) > 0)
is_region_clipped = is_low_clipped | is_high_clipped
low_clip = masked_batch_mean(is_low_clipped.float())
high_clip = masked_batch_mean(is_high_clipped.float())
clip_ratio = masked_batch_mean(is_region_clipped.float())
gathered_low_clip = self.accelerator.gather_for_metrics(low_clip)
self._metrics[mode]['clip_ratio/low_mean'].append(gathered_low_clip.nanmean().item())
self._metrics[mode]['clip_ratio/low_min'].append(nanmin(gathered_low_clip).item())
gathered_high_clip = self.accelerator.gather_for_metrics(high_clip)
self._metrics[mode]['clip_ratio/high_mean'].append(gathered_high_clip.nanmean().item())
self._metrics[mode]['clip_ratio/high_max'].append(nanmax(gathered_high_clip).item())
gathered_clip_ratio = self.accelerator.gather_for_metrics(clip_ratio)
self._metrics[mode]['clip_ratio/region_mean'].append(gathered_clip_ratio.nanmean().item())
return loss
@contextmanager
def padding_free_context(self, model: torch.nn.Module):
ctx = {}
def _padding_free_input_hook(module, args, kwargs):
attention_mask = kwargs['attention_mask']
# used in _padding_free_output_hook
ctx['padding_left'] = (attention_mask[:, -1].sum() == attention_mask.shape[0])
if 'input_ids' in kwargs and kwargs.get('input_ids') is not None:
# llm models
kwargs['position_ids'] = torch.arange(kwargs['input_ids'].shape[1]).unsqueeze(0).repeat(
kwargs['input_ids'].shape[0], 1).to(kwargs['input_ids'].dtype).to(kwargs['input_ids'].device)
kwargs['input_ids'] = kwargs['input_ids'][attention_mask.bool()].unsqueeze(0)
else:
# mllm models
kwargs['position_ids'] = torch.arange(kwargs['inputs_embeds'].shape[1]).unsqueeze(0).repeat(
kwargs['inputs_embeds'].shape[0], 1).to(torch.int64).to(kwargs['inputs_embeds'].device)
kwargs['inputs_embeds'] = kwargs['inputs_embeds'][attention_mask.bool()].unsqueeze(0)
kwargs['position_ids'] = kwargs['position_ids'][attention_mask.bool()].unsqueeze(0)
kwargs.pop('attention_mask', None)
return args, kwargs
def _padding_free_output_hook(module, args, kwargs, result):
position_ids = kwargs['position_ids']
seq_lengths = []
pos = position_ids[0]
resets = torch.where(pos[1:] < pos[:-1])[0] + 1
if len(resets) == 0:
# Only one sequence in this batch item
seq_lengths = [pos.max().item() + 1]
else:
# Multiple sequences
start = 0
for end in resets:
seq_lengths.append(end - start)
start = end
seq_lengths.append(pos.shape[0] - start)
max_length = max(seq_lengths)
last_hidden_state = result.last_hidden_state.squeeze(0)
unpacked_logits = []
start = 0
for length in seq_lengths:
seq_state = last_hidden_state[start:start + length]
padding = torch.zeros(
(max_length - length,
last_hidden_state.shape[-1])).to(last_hidden_state.dtype).to(last_hidden_state.device)
# re-padding
if ctx['padding_left']:
seq_state = torch.cat((padding, seq_state), dim=0)
else:
seq_state = torch.cat((seq_state, padding), dim=0)
unpacked_logits.append(seq_state)
start += length
result.last_hidden_state = torch.stack(unpacked_logits, dim=0)
return result
if self.padding_free:
llm_model = get_llm_model(model)
if hasattr(llm_model, 'thinker'):
base_model = llm_model.thinker.model
else:
base_model = llm_model.model
remove_handle1 = base_model.register_forward_pre_hook(
_padding_free_input_hook, with_kwargs=True, prepend=True)
remove_handle2 = base_model.register_forward_hook(_padding_free_output_hook, with_kwargs=True, prepend=True)
yield
if self.padding_free:
remove_handle1.remove()
remove_handle2.remove()
@patch_profiling_decorator
def _get_per_token_logps_and_entropies(self,
model,
inputs,
compute_entropy=False) -> Tuple[torch.Tensor, Optional[torch.Tensor]]:
logits_to_keep = inputs['logits_to_keep']
input_ids = inputs['input_ids']
unwrapped_model = self.accelerator.unwrap_model(model)
if is_peft_model(unwrapped_model):
parameters = inspect.signature(unwrapped_model.base_model.model.forward).parameters
else:
parameters = inspect.signature(unwrapped_model.forward).parameters
use_local_entropy = not hasattr(super(), '_get_per_token_logps_and_entropies') and compute_entropy
can_use_super = (not unwrapped_model.model_meta.is_multimodal and 'logits_to_keep' in parameters
and not use_local_entropy)
if can_use_super:
# save memory
with self.padding_free_context(model):
if hasattr(super(), '_get_per_token_logps_and_entropies'):
logps, entropies = super()._get_per_token_logps_and_entropies(
model, input_ids, inputs['attention_mask'], logits_to_keep, compute_entropy=compute_entropy)
else:
logps = super()._get_per_token_logps(model, input_ids, inputs['attention_mask'], logits_to_keep)
entropies = None
else:
inputs = {
k: v
for k, v in inputs.items() if k not in [
'logits_to_keep', 'completion_mask', 'ref_per_token_logps', 'advantages', 'old_per_token_logps',
'truncated_mask'
]
}
with self._template_context(self.template), self.padding_free_context(model):
logits = model(**inputs).logits
# exclude the last logit: it corresponds to the next token pred
logits = logits[:, -(logits_to_keep + 1):-1, :]
logits = logits / self.temperature
input_ids = input_ids[:, -logits_to_keep:]
logps = selective_log_softmax(logits, input_ids) # compute logprobs for the input tokens
entropies = None
if compute_entropy:
entropies = entropy_from_logits(logits)
return logps, entropies
@patch_profiling_decorator
def _get_last_hidden_state(self, unwrapped_model, inputs, logits_to_keep):
# unwrap the model to access the model.model
if is_peft_model(unwrapped_model):
unwrapped_model = unwrapped_model.base_model.model
if not unwrapped_model.model_meta.is_multimodal:
last_hidden_state = unwrapped_model.model(
input_ids=inputs['input_ids'], attention_mask=inputs['attention_mask']).last_hidden_state
else:
inputs = {
k: v
for k, v in inputs.items() if k not in [
'logits_to_keep', 'completion_mask', 'ref_per_token_logps', 'advantages', 'old_per_token_logps',
'truncated_mask'
]
}
with self._template_context(self.template):
outputs = unwrapped_model(**inputs, output_hidden_states=True)
last_hidden_state = outputs.hidden_states[-1]
last_hidden_state = last_hidden_state[:, :-1, :] # (B, L-1, H)
if logits_to_keep is not None:
last_hidden_state = last_hidden_state[:, -logits_to_keep:, :] # (B, logits_to_keep, H)
return last_hidden_state
def compute_liger_loss(self, unwrapped_model, inputs):
# Compute the per-token log probabilities for the model
input_ids = inputs['input_ids']
logits_to_keep = inputs['logits_to_keep']
completion_ids = input_ids[:, -logits_to_keep:]
completion_mask = inputs['completion_mask']
# Compute the KL divergence between the model and the reference model
ref_per_token_logps = None
if self.beta != 0.0:
with torch.no_grad():
if self.ref_model is not None:
ref_per_token_logps, _ = self._get_per_token_logps_and_entropies(self.ref_model, inputs)
else:
with self.accelerator.unwrap_model(self.model).disable_adapter():
ref_per_token_logps, _ = self._get_per_token_logps_and_entropies(self.model, inputs)
# get the last hidden state of the model
last_hidden_state = self._get_last_hidden_state(unwrapped_model, inputs, logits_to_keep)
# compute loss and metrics using liger grpo loss
loss, metrics = self.liger_grpo_loss(
_input=last_hidden_state,
lin_weight=unwrapped_model.lm_head.weight,
selected_token_ids=completion_ids,
attention_mask=completion_mask,
advantages=inputs['advantages'],
bias=unwrapped_model.lm_head.bias,
old_per_token_logps=inputs['old_per_token_logps'],
ref_per_token_logps=ref_per_token_logps,
)
# Extract metrics from the liger_grpo_loss output
# KL divergence is the first metric when beta is non-zero
mean_kl = metrics[0] if self.beta != 0.0 else None
clip_ratio = metrics[-1]
mode = 'eval' if self.control.should_evaluate else 'train'
if self.beta != 0.0:
self._metrics[mode]['kl'].append(self.accelerator.gather_for_metrics(mean_kl).mean().item())
self._metrics[mode]['clip_ratio'].append(self.accelerator.gather_for_metrics(clip_ratio).mean().item())
return loss
def evaluation_loop(self, dataloader, *args, **kwargs):
# Wait for the training rollout to complete
if self.args.async_generate:
while not self.is_async_generate_train_rollout_done():
time.sleep(0.1)
if self._queue.empty() and self.args.async_generate:
self._prefetch(dataloader)
metric_key_prefix = kwargs['metric_key_prefix']
output = super().evaluation_loop(dataloader, *args, **kwargs)
metrics = {f'{metric_key_prefix}_{key}': sum(val) / len(val) for key, val in self._metrics['eval'].items()}
output.metrics.update(metrics)
self.eval_flag = True
return output
def training_step(self, model: nn.Module, inputs: InputsType, num_items_in_batch=None) -> torch.Tensor:
if self.args.async_generate:
# Wait for the eval rollout to complete
while not self.is_async_generate_eval_rollout_done():
time.sleep(0.1)
return super().training_step(model, inputs, num_items_in_batch)
def _engine_infer(
self,
infer_requests: InputsType,
request_config: Optional[RequestConfig] = None,
*,
use_tqdm: Optional[bool] = False,
) -> List[ChatCompletionResponse]:
with patch_profiling_context(self, 'generate'):
if self.vllm_mode == 'server':
request_keys = ['messages', 'images', 'audios', 'videos', 'tools', 'objects']
infer_requests = [{
**{k: request[k]
for k in request_keys if k in request},
**({
'data_dict': {k: request[k]
for k in request if k not in request_keys}
} if (
(self.multi_turn_scheduler and self.vllm_use_async_engine) or
(self.vllm_use_async_engine and self.use_gym_env)
) else {}) # use gym infer
} for request in infer_requests]
self._process_infer_requests_images(infer_requests)
return self.vllm_client.infer(infer_requests, asdict(request_config), use_tqdm=use_tqdm)
else:
return self.engine.infer(infer_requests, request_config, use_tqdm=use_tqdm)
def _process_infer_requests_images(self, infer_requests: InputsType):
# Process image format into a format that session.post can accept
import base64
if not any('images' in request for request in infer_requests):
return
for request in infer_requests:
if 'images' not in request:
continue
for i, img in enumerate(request['images']):
if 'bytes' in img and img['bytes']:
request['images'][i] = base64.b64encode(img['bytes']).decode('utf-8')
elif 'path' in img and img['path']:
request['images'][i] = img['path']
return
def old_policy(self):
return self.num_iterations > 1 or self.args.gradient_accumulation_steps % self.args.steps_per_generation != 0
@property
def _queue(self):
if self.control.should_evaluate:
return self.eval_queue
else:
return self.train_queue
@torch.no_grad()
def offload_model(self, model):
for param in model.parameters():
param.data = param.data.to(torch.device('cpu'), non_blocking=True)
@torch.no_grad()
def load_model(self, model):
device = get_current_device()
for param in model.parameters():
param.data = param.data.to(device, non_blocking=True)
@torch.no_grad()
def offload_optimizer(self):
if not self.optimizer.state:
return
for param_group in self.optimizer.param_groups:
for param in param_group['params']:
state = self.optimizer.state[param]
for key, value in state.items():
if isinstance(value, torch.Tensor):
state[key] = value.to('cpu', non_blocking=True)
@torch.no_grad()
def load_optimizer(self):
device = get_current_device()
if not self.optimizer.state:
return
for param_group in self.optimizer.param_groups:
for param in param_group['params']:
state = self.optimizer.state[param]
for key, value in state.items():
if isinstance(value, torch.Tensor):
state[key] = value.to(device, non_blocking=True)
@contextmanager
def multi_turn_completion_length_context(self):
"""
Context manager that temporarily adjusts the engine's max length handling
for multi-turn generation scenarios.
Ensures the total sequence length (prompt + completion) never exceeds:
min(original_max_len, prompt_tokens + max_completion_length)
"""
if not (self.multi_turn_scheduler and
self.use_fast_infer) or self.vllm_mode == 'server' or self.completion_length_limit_scope == 'per_round':
yield
return
original_fn = self.engine.set_default_max_tokens
original_max_len = self.engine.max_model_len
def set_default_max_tokens(_self, request_config: RequestConfig, inputs: Dict[str, Any]) -> None:
# Calculate required context window
original_max_len = _self.max_model_len or 8192
assert isinstance(inputs, dict)
prompt_tokens = _self._get_num_tokens(inputs)
if not hasattr(_self, 'set_grpo_max_model_len'):
# set max model len in first round
max_len = min(original_max_len, prompt_tokens + request_config.max_tokens)
_self.max_model_len = max_len
_self.set_grpo_max_model_len = True
else:
if _self.max_model_len <= prompt_tokens:
# modify max_model_len > prompt_tokens to avoid crash
num_tokens_avoid_crash = 10
_self.max_model_len = (prompt_tokens + num_tokens_avoid_crash)
request_config.max_tokens = num_tokens_avoid_crash
original_fn(request_config, inputs)
try:
self.engine.set_default_max_tokens = MethodType(set_default_max_tokens, self.engine)
yield
finally:
self.engine.set_default_max_tokens = original_fn
self.engine.max_model_len = original_max_len
del self.engine.set_grpo_max_model_len
def resample_truncated_inputs(self, inputs: InputsType, n_try_fetch: int = 10) -> InputsType:
template = self.template
for i, data in enumerate(inputs):
n_try = 0
while True:
try:
template.encode(data)
inputs[i] = data
break
except MaxLengthError:
n_try += 1
if n_try > n_try_fetch:
raise RuntimeError('Failed to resample a valid data.',
'You can avoid this issue by increasing `max_length` or ',
'modifying the `truncation_strategy`.')
data = next(self.truncated_resample_iterator)[0]
return inputs
def log(self, logs: dict[str, float], start_time: Optional[float] = None) -> None:
mode = 'train' if self.model.training else 'eval'
metrics = {key: sum(val) / len(val) for key, val in self._metrics[mode].items()} # average the metrics
# This method can be called both in training and evaluation. When called in evaluation, the keys in `logs`
# start with "eval_". We need to add the prefix "eval_" to the keys in `metrics` to match the format.
if mode == 'eval':
metrics = {f'eval_{key}': val for key, val in metrics.items()}
logs = {**logs, **metrics}
if version.parse(transformers.__version__) >= version.parse('4.47.0.dev0'):
super().log(logs, start_time)
else: # transformers<=4.46
super().log(logs)
self._metrics[mode].clear()
# - entropy only includes samples that went through training (computed in _compute_loss)
# - Other fields (e.g., prompt/completion/reward) are collected from rollout (in _prepare_inputs)
# Therefore, if entropy exists, to ensure length consistency across fields,
# we align all data based on the number of samples in entropy.
seen_nums = len(self._textual_logs['entropy']) \
if 'entropy' in self._textual_logs else len(self._textual_logs['prompt'])
if self.accelerator.is_main_process and self.log_completions:
table = {
'step': [str(self.state.global_step)] * seen_nums,
'prompt': list(self._textual_logs['prompt'])[:seen_nums],
'completion': list(self._textual_logs['completion'])[:seen_nums],
**{k: list(v)[:seen_nums]
for k, v in self._textual_logs['rewards'].items()},
}
if self.use_gym_env:
table['trajactory_info'] = self._textual_logs['trajactory_info']
if self.args.log_entropy:
table.update({'entropy': self._textual_logs['entropy']})
self.jsonl_writer.append(table)
if self.args.report_to and 'wandb' in self.args.report_to and wandb.run is not None:
import pandas as pd
df = pd.DataFrame(table)
if self.wandb_log_unique_prompts:
df = df.drop_duplicates(subset=['prompt'])
wandb.log({'completions': wandb.Table(dataframe=df)})
if self.args.report_to and 'swanlab' in self.args.report_to and swanlab.get_run() is not None:
headers = list(table.keys())
rows = []
for i in range(len(table['step'])):
row = []
for header in headers:
row.append(table[header][i])
rows.append(row)
swanlab.log({'completions': swanlab.echarts.Table().add(headers, rows)})
def is_async_generate_eval_rollout_done(self):
return not self.eval_flag or not self.eval_queue.empty()
def is_async_generate_train_rollout_done(self):
return not self.train_queue.empty()
def inputs_to_rolloutrequest(self, inputs: InputsType) -> List[RolloutInferRequest]:
"""Convert a list of inputs to a list of RolloutInferRequest objects
If the input contains a 'data_dict' key, it will be used as the base for the new data_dict.
For other keys, if they overlap with keys in data_dict, the values from data_dict will be used.
Non-overlapping keys will be added to data_dict.
Args:
inputs: List of input dictionaries
Returns:
List of RolloutInferRequest objects
"""
request_keys = ['messages', 'images', 'audios', 'videos', 'tools', 'objects']
infer_requests = []
for request in inputs:
# Get the base data_dict if it exists in the input
base_data_dict = {}
if 'data_dict' in request:
if isinstance(request['data_dict'], dict):
base_data_dict = request['data_dict']
else:
raise ValueError('data_dict exists but is not a dictionary')
# Collect all non-request_keys items as extra fields
extra_data = {k: request[k] for k in request if k not in request_keys and k != 'data_dict'}
# Merge the data_dict, keeping keys from base_data_dict as priority
final_data_dict = {**extra_data, **base_data_dict}
# Create RolloutInferRequest instance
req_args = {k: request[k] for k in request_keys if k in request}
infer_requests.append(RolloutInferRequest(**req_args, data_dict=final_data_dict))
return infer_requests
@contextmanager
def offload_context(self):
if self.args.offload_model:
self.offload_model(self.accelerator.unwrap_model(self.model))
if self.ref_model:
self.offload_model(self.ref_model)
if getattr(self, 'optimizer', None) and self.args.offload_optimizer:
self.offload_optimizer()
empty_cache()
try:
yield
finally:
# reload (load back) model when exiting context
if self.args.offload_model:
self.load_model(self.accelerator.unwrap_model(self.model))
if self.ref_model:
self.load_model(self.ref_model)
if getattr(self, 'optimizer', None) and self.args.offload_optimizer:
self.load_optimizer()
empty_cache()