Source code for ray.rllib.policy.torch_policy

import numpy as np
import time

from ray.rllib.policy.policy import Policy, LEARNER_STATS_KEY
from ray.rllib.policy.sample_batch import SampleBatch
from ray.rllib.policy.rnn_sequencing import pad_batch_to_sequences_of_same_size
from ray.rllib.utils import force_list
from ray.rllib.utils.annotations import override, DeveloperAPI
from ray.rllib.utils.framework import try_import_torch
from ray.rllib.utils.schedules import ConstantSchedule, PiecewiseSchedule
from ray.rllib.utils.torch_ops import convert_to_non_torch_type, \
    convert_to_torch_tensor
from ray.rllib.utils.tracking_dict import UsageTrackingDict

torch, _ = try_import_torch()


[docs]class TorchPolicy(Policy): """Template for a PyTorch policy and loss to use with RLlib. This is similar to TFPolicy, but for PyTorch. Attributes: observation_space (gym.Space): observation space of the policy. action_space (gym.Space): action space of the policy. config (dict): config of the policy. model (TorchModel): Torch model instance. dist_class (type): Torch action distribution class. """ def __init__(self, observation_space, action_space, config, *, model, loss, action_distribution_class, action_sampler_fn=None, action_distribution_fn=None, max_seq_len=20, get_batch_divisibility_req=None): """Build a policy from policy and loss torch modules. Note that model will be placed on GPU device if CUDA_VISIBLE_DEVICES is set. Only single GPU is supported for now. Arguments: observation_space (gym.Space): observation space of the policy. action_space (gym.Space): action space of the policy. config (dict): The Policy config dict. model (nn.Module): PyTorch policy module. Given observations as input, this module must return a list of outputs where the first item is action logits, and the rest can be any value. loss (func): Function that takes (policy, model, dist_class, train_batch) and returns a single scalar loss. action_distribution_class (ActionDistribution): Class for action distribution. action_sampler_fn (Optional[callable]): A callable returning a sampled action and its log-likelihood given some (obs and state) inputs. action_distribution_fn (Optional[callable]): A callable returning distribution inputs (parameters), a dist-class to generate an action distribution object from, and internal-state outputs (or an empty list if not applicable). Note: No Exploration hooks have to be called from within `action_distribution_fn`. It's should only perform a simple forward pass through some model. If None, pass inputs through `self.model()` to get the distribution inputs. max_seq_len (int): Max sequence length for LSTM training. get_batch_divisibility_req (Optional[callable]): Optional callable that returns the divisibility requirement for sample batches. """ self.framework = "torch" super().__init__(observation_space, action_space, config) self.device = (torch.device("cuda") if torch.cuda.is_available() else torch.device("cpu")) self.model = model.to(self.device) self.exploration = self._create_exploration() self.unwrapped_model = model # used to support DistributedDataParallel self._loss = loss self._optimizers = force_list(self.optimizer()) self.dist_class = action_distribution_class self.action_sampler_fn = action_sampler_fn self.action_distribution_fn = action_distribution_fn # If set, means we are using distributed allreduce during learning. self.distributed_world_size = None self.max_seq_len = max_seq_len self.batch_divisibility_req = \ get_batch_divisibility_req(self) if get_batch_divisibility_req \ else 1
[docs] @override(Policy) def compute_actions(self, obs_batch, state_batches=None, prev_action_batch=None, prev_reward_batch=None, info_batch=None, episodes=None, explore=None, timestep=None, **kwargs): explore = explore if explore is not None else self.config["explore"] timestep = timestep if timestep is not None else self.global_timestep with torch.no_grad(): seq_lens = torch.ones(len(obs_batch), dtype=torch.int32) input_dict = self._lazy_tensor_dict({ SampleBatch.CUR_OBS: obs_batch, "is_training": False, }) if prev_action_batch is not None: input_dict[SampleBatch.PREV_ACTIONS] = prev_action_batch if prev_reward_batch is not None: input_dict[SampleBatch.PREV_REWARDS] = prev_reward_batch state_batches = [ self._convert_to_tensor(s) for s in (state_batches or []) ] if self.action_sampler_fn: action_dist = dist_inputs = None state_out = [] actions, logp = self.action_sampler_fn( self, self.model, input_dict[SampleBatch.CUR_OBS], explore=explore, timestep=timestep) else: # Call the exploration before_compute_actions hook. self.exploration.before_compute_actions( explore=explore, timestep=timestep) if self.action_distribution_fn: dist_inputs, dist_class, state_out = \ self.action_distribution_fn( self, self.model, input_dict[SampleBatch.CUR_OBS], explore=explore, timestep=timestep, is_training=False) else: dist_class = self.dist_class dist_inputs, state_out = self.model( input_dict, state_batches, seq_lens) action_dist = dist_class(dist_inputs, self.model) # Get the exploration action from the forward results. actions, logp = \ self.exploration.get_exploration_action( action_distribution=action_dist, timestep=timestep, explore=explore) input_dict[SampleBatch.ACTIONS] = actions # Add default and custom fetches. extra_fetches = self.extra_action_out(input_dict, state_batches, self.model, action_dist) # Action-logp and action-prob. if logp is not None: logp = convert_to_non_torch_type(logp) extra_fetches[SampleBatch.ACTION_PROB] = np.exp(logp) extra_fetches[SampleBatch.ACTION_LOGP] = logp # Action-dist inputs. if dist_inputs is not None: extra_fetches[SampleBatch.ACTION_DIST_INPUTS] = dist_inputs return convert_to_non_torch_type((actions, state_out, extra_fetches))
[docs] @override(Policy) def compute_log_likelihoods(self, actions, obs_batch, state_batches=None, prev_action_batch=None, prev_reward_batch=None): if self.action_sampler_fn and self.action_distribution_fn is None: raise ValueError("Cannot compute log-prob/likelihood w/o an " "`action_distribution_fn` and a provided " "`action_sampler_fn`!") with torch.no_grad(): input_dict = self._lazy_tensor_dict({ SampleBatch.CUR_OBS: obs_batch, SampleBatch.ACTIONS: actions }) if prev_action_batch is not None: input_dict[SampleBatch.PREV_ACTIONS] = prev_action_batch if prev_reward_batch is not None: input_dict[SampleBatch.PREV_REWARDS] = prev_reward_batch seq_lens = torch.ones(len(obs_batch), dtype=torch.int32) # Exploration hook before each forward pass. self.exploration.before_compute_actions(explore=False) # Action dist class and inputs are generated via custom function. if self.action_distribution_fn: dist_inputs, dist_class, _ = self.action_distribution_fn( policy=self, model=self.model, obs_batch=input_dict[SampleBatch.CUR_OBS], explore=False, is_training=False) # Default action-dist inputs calculation. else: dist_class = self.dist_class dist_inputs, _ = self.model(input_dict, state_batches, seq_lens) action_dist = dist_class(dist_inputs, self.model) log_likelihoods = action_dist.logp(input_dict[SampleBatch.ACTIONS]) return log_likelihoods
[docs] @override(Policy) def learn_on_batch(self, postprocessed_batch): # Get batch ready for RNNs, if applicable. pad_batch_to_sequences_of_same_size( postprocessed_batch, max_seq_len=self.max_seq_len, shuffle=False, batch_divisibility_req=self.batch_divisibility_req) train_batch = self._lazy_tensor_dict(postprocessed_batch) loss_out = force_list( self._loss(self, self.model, self.dist_class, train_batch)) assert len(loss_out) == len(self._optimizers) # assert not any(torch.isnan(l) for l in loss_out) # Loop through all optimizers. grad_info = {"allreduce_latency": 0.0} for i, opt in enumerate(self._optimizers): # Erase gradients in all vars of this optimizer. opt.zero_grad() # Recompute gradients of loss over all variables. loss_out[i].backward(retain_graph=(i < len(self._optimizers) - 1)) grad_info.update(self.extra_grad_process(opt, loss_out[i])) if self.distributed_world_size: grads = [] for param_group in opt.param_groups: for p in param_group["params"]: if p.grad is not None: grads.append(p.grad) start = time.time() if torch.cuda.is_available(): # Sadly, allreduce_coalesced does not work with CUDA yet. for g in grads: torch.distributed.all_reduce( g, op=torch.distributed.ReduceOp.SUM) else: torch.distributed.all_reduce_coalesced( grads, op=torch.distributed.ReduceOp.SUM) for param_group in opt.param_groups: for p in param_group["params"]: if p.grad is not None: p.grad /= self.distributed_world_size grad_info["allreduce_latency"] += time.time() - start # Step the optimizer. opt.step() grad_info["allreduce_latency"] /= len(self._optimizers) grad_info.update(self.extra_grad_info(train_batch)) return {LEARNER_STATS_KEY: grad_info}
[docs] @override(Policy) def compute_gradients(self, postprocessed_batch): train_batch = self._lazy_tensor_dict(postprocessed_batch) loss_out = force_list( self._loss(self, self.model, self.dist_class, train_batch)) assert len(loss_out) == len(self._optimizers) grad_process_info = {} grads = [] for i, opt in enumerate(self._optimizers): opt.zero_grad() loss_out[i].backward() grad_process_info = self.extra_grad_process(opt, loss_out[i]) # Note that return values are just references; # calling zero_grad will modify the values for param_group in opt.param_groups: for p in param_group["params"]: if p.grad is not None: grads.append(p.grad.data.cpu().numpy()) else: grads.append(None) grad_info = self.extra_grad_info(train_batch) grad_info.update(grad_process_info) return grads, {LEARNER_STATS_KEY: grad_info}
[docs] @override(Policy) def apply_gradients(self, gradients): # TODO(sven): Not supported for multiple optimizers yet. assert len(self._optimizers) == 1 for g, p in zip(gradients, self.model.parameters()): if g is not None: p.grad = torch.from_numpy(g).to(self.device) self._optimizers[0].step()
[docs] @override(Policy) def get_weights(self): return { k: v.cpu().detach().numpy() for k, v in self.model.state_dict().items() }
[docs] @override(Policy) def set_weights(self, weights): weights = convert_to_torch_tensor(weights, device=self.device) self.model.load_state_dict(weights)
[docs] @override(Policy) def is_recurrent(self): return len(self.model.get_initial_state()) > 0
[docs] @override(Policy) def num_state_tensors(self): return len(self.model.get_initial_state())
[docs] @override(Policy) def get_initial_state(self): return [ s.cpu().detach().numpy() for s in self.model.get_initial_state() ]
[docs] def extra_grad_process(self, optimizer, loss): """Called after each optimizer.zero_grad() + loss.backward() call. Called for each self._optimizers/loss-value pair. Allows for gradient processing before optimizer.step() is called. E.g. for gradient clipping. Args: optimizer (torch.optim.Optimizer): A torch optimizer object. loss (torch.Tensor): The loss tensor associated with the optimizer. Returns: dict: An info dict. """ return {}
[docs] def extra_action_out(self, input_dict, state_batches, model, action_dist): """Returns dict of extra info to include in experience batch. Args: input_dict (dict): Dict of model input tensors. state_batches (list): List of state tensors. model (TorchModelV2): Reference to the model. action_dist (TorchActionDistribution): Torch action dist object to get log-probs (e.g. for already sampled actions). """ return {}
[docs] def extra_grad_info(self, train_batch): """Return dict of extra grad info.""" return {}
[docs] def optimizer(self): """Custom PyTorch optimizer to use.""" if hasattr(self, "config"): return torch.optim.Adam( self.model.parameters(), lr=self.config["lr"]) else: return torch.optim.Adam(self.model.parameters())
def _lazy_tensor_dict(self, postprocessed_batch): train_batch = UsageTrackingDict(postprocessed_batch) train_batch.set_get_interceptor(self._convert_to_tensor) return train_batch def _convert_to_tensor(self, arr): if torch.is_tensor(arr): return arr.to(self.device) tensor = torch.from_numpy(np.asarray(arr)) if tensor.dtype == torch.double: tensor = tensor.float() return tensor.to(self.device)
[docs] @override(Policy) def export_model(self, export_dir): """TODO(sven): implement for torch. """ raise NotImplementedError
[docs] @override(Policy) def export_checkpoint(self, export_dir): """TODO(sven): implement for torch. """ raise NotImplementedError
[docs] @override(Policy) def import_model_from_h5(self, import_file): """Imports weights into torch model.""" return self.model.import_from_h5(import_file)
@DeveloperAPI class LearningRateSchedule: """Mixin for TFPolicy that adds a learning rate schedule.""" @DeveloperAPI def __init__(self, lr, lr_schedule): self.cur_lr = lr if lr_schedule is None: self.lr_schedule = ConstantSchedule(lr, framework=None) else: self.lr_schedule = PiecewiseSchedule( lr_schedule, outside_value=lr_schedule[-1][-1], framework=None) @override(Policy) def on_global_var_update(self, global_vars): super(LearningRateSchedule, self).on_global_var_update(global_vars) self.cur_lr = self.lr_schedule.value(global_vars["timestep"]) @override(TorchPolicy) def optimizer(self): for opt in self._optimizers: for p in opt.param_groups: p["lr"] = self.cur_lr return self._optimizers @DeveloperAPI class EntropyCoeffSchedule: """Mixin for TorchPolicy that adds entropy coeff decay.""" @DeveloperAPI def __init__(self, entropy_coeff, entropy_coeff_schedule): self.entropy_coeff = entropy_coeff if entropy_coeff_schedule is None: self.entropy_coeff_schedule = ConstantSchedule( entropy_coeff, framework=None) else: # Allows for custom schedule similar to lr_schedule format if isinstance(entropy_coeff_schedule, list): self.entropy_coeff_schedule = PiecewiseSchedule( entropy_coeff_schedule, outside_value=entropy_coeff_schedule[-1][-1], framework=None) else: # Implements previous version but enforces outside_value self.entropy_coeff_schedule = PiecewiseSchedule( [[0, entropy_coeff], [entropy_coeff_schedule, 0.0]], outside_value=0.0, framework=None) @override(Policy) def on_global_var_update(self, global_vars): super(EntropyCoeffSchedule, self).on_global_var_update(global_vars) self.entropy_coeff = self.entropy_coeff_schedule.value( global_vars["timestep"])