Source code for ray.rllib.execution.train_ops

import logging
import numpy as np
import math
import tree  # pip install dm_tree
from typing import List, Tuple, Any

import ray
from ray.rllib.evaluation.metrics import get_learner_stats
from ray.rllib.evaluation.worker_set import WorkerSet
from ray.rllib.execution.common import \
    AGENT_STEPS_TRAINED_COUNTER, APPLY_GRADS_TIMER, COMPUTE_GRADS_TIMER, \
    LAST_TARGET_UPDATE_TS, LEARNER_INFO, LEARN_ON_BATCH_TIMER, \
    LOAD_BATCH_TIMER, NUM_TARGET_UPDATES, STEPS_SAMPLED_COUNTER, \
    STEPS_TRAINED_COUNTER, WORKER_UPDATE_TIMER, _check_sample_batch_type, \
    _get_global_vars, _get_shared_metrics
from ray.rllib.policy.policy import LEARNER_STATS_KEY
from ray.rllib.policy.sample_batch import SampleBatch, DEFAULT_POLICY_ID, \
    MultiAgentBatch
from ray.rllib.utils.framework import try_import_tf
from ray.rllib.utils.sgd import do_minibatch_sgd
from ray.rllib.utils.typing import PolicyID, SampleBatchType, ModelGradients

tf1, tf, tfv = try_import_tf()

logger = logging.getLogger(__name__)


[docs]class TrainOneStep: """Callable that improves the policy and updates workers. This should be used with the .for_each() operator. A tuple of the input and learner stats will be returned. Examples: >>> rollouts = ParallelRollouts(...) >>> train_op = rollouts.for_each(TrainOneStep(workers)) >>> print(next(train_op)) # This trains the policy on one batch. SampleBatch(...), {"learner_stats": ...} Updates the STEPS_TRAINED_COUNTER counter and LEARNER_INFO field in the local iterator context. """ def __init__(self, workers: WorkerSet, policies: List[PolicyID] = frozenset([]), num_sgd_iter: int = 1, sgd_minibatch_size: int = 0): self.workers = workers self.local_worker = workers.local_worker() self.policies = policies self.num_sgd_iter = num_sgd_iter self.sgd_minibatch_size = sgd_minibatch_size def __call__(self, batch: SampleBatchType) -> (SampleBatchType, List[dict]): _check_sample_batch_type(batch) metrics = _get_shared_metrics() learn_timer = metrics.timers[LEARN_ON_BATCH_TIMER] with learn_timer: # Subsample minibatches (size=`sgd_minibatch_size`) from the # train batch and loop through train batch `num_sgd_iter` times. if self.num_sgd_iter > 1 or self.sgd_minibatch_size > 0: lw = self.workers.local_worker() info = do_minibatch_sgd( batch, { pid: lw.get_policy(pid) for pid in self.policies or self.local_worker.policies_to_train }, lw, self.num_sgd_iter, self.sgd_minibatch_size, []) # Single update step using train batch. else: info = self.workers.local_worker().learn_on_batch(batch) metrics.info[LEARNER_INFO] = info learn_timer.push_units_processed(batch.count) metrics.counters[STEPS_TRAINED_COUNTER] += batch.count if isinstance(batch, MultiAgentBatch): metrics.counters[ AGENT_STEPS_TRAINED_COUNTER] += batch.agent_steps() # Update weights - after learning on the local worker - on all remote # workers. if self.workers.remote_workers(): with metrics.timers[WORKER_UPDATE_TIMER]: weights = ray.put(self.workers.local_worker().get_weights( self.policies or self.local_worker.policies_to_train)) for e in self.workers.remote_workers(): e.set_weights.remote(weights, _get_global_vars()) # Also update global vars of the local worker. self.workers.local_worker().set_global_vars(_get_global_vars()) return batch, info
[docs]class MultiGPUTrainOneStep: """Multi-GPU version of TrainOneStep. This should be used with the .for_each() operator. A tuple of the input and learner stats will be returned. Examples: >>> rollouts = ParallelRollouts(...) >>> train_op = rollouts.for_each(MultiGPUTrainOneStep(workers, ...)) >>> print(next(train_op)) # This trains the policy on one batch. SampleBatch(...), {"learner_stats": ...} Updates the STEPS_TRAINED_COUNTER counter and LEARNER_INFO field in the local iterator context. """ def __init__(self, *, workers: WorkerSet, sgd_minibatch_size: int, num_sgd_iter: int, num_gpus: int, shuffle_sequences: bool, _fake_gpus: bool = False, framework: str = "tf"): self.workers = workers self.local_worker = workers.local_worker() self.num_sgd_iter = num_sgd_iter self.sgd_minibatch_size = sgd_minibatch_size self.shuffle_sequences = shuffle_sequences self.framework = framework # Collect actual GPU devices to use. if not num_gpus: _fake_gpus = True num_gpus = 1 type_ = "cpu" if _fake_gpus else "gpu" self.devices = [ "/{}:{}".format(type_, 0 if _fake_gpus else i) for i in range(int(math.ceil(num_gpus))) ] # Make sure total batch size is dividable by the number of devices. # Batch size per tower. self.per_device_batch_size = sgd_minibatch_size // len(self.devices) # Total batch size. self.batch_size = self.per_device_batch_size * len(self.devices) assert self.batch_size % len(self.devices) == 0 assert self.batch_size >= len(self.devices), "Batch size too small!" def __call__(self, samples: SampleBatchType) -> (SampleBatchType, List[dict]): _check_sample_batch_type(samples) # Handle everything as if multi agent. if isinstance(samples, SampleBatch): samples = MultiAgentBatch({ DEFAULT_POLICY_ID: samples }, samples.count) metrics = _get_shared_metrics() load_timer = metrics.timers[LOAD_BATCH_TIMER] learn_timer = metrics.timers[LEARN_ON_BATCH_TIMER] # Load data into GPUs. with load_timer: num_loaded_samples = {} for policy_id, batch in samples.policy_batches.items(): # Not a policy-to-train. if policy_id not in self.local_worker.policies_to_train: continue # Decompress SampleBatch, in case some columns are compressed. batch.decompress_if_needed() # Load the entire train batch into the Policy's only buffer # (idx=0). Policies only have >1 buffers, if we are training # asynchronously. num_loaded_samples[policy_id] = self.local_worker.policy_map[ policy_id].load_batch_into_buffer( batch, buffer_index=0) # Execute minibatch SGD on loaded data. with learn_timer: fetches = {} for policy_id, samples_per_device in num_loaded_samples.items(): policy = self.local_worker.policy_map[policy_id] num_batches = max( 1, int(samples_per_device) // int(self.per_device_batch_size)) logger.debug("== sgd epochs for {} ==".format(policy_id)) batch_fetches_all_towers = [] for _ in range(self.num_sgd_iter): permutation = np.random.permutation(num_batches) for batch_index in range(num_batches): # Learn on the pre-loaded data in the buffer. # Note: For minibatch SGD, the data is an offset into # the pre-loaded entire train batch. batch_fetches = policy.learn_on_loaded_batch( permutation[batch_index] * self.per_device_batch_size, buffer_index=0) # No towers: Single CPU. if "tower_0" not in batch_fetches: batch_fetches_all_towers.append(batch_fetches) else: batch_fetches_all_towers.append( tree.map_structure_with_path( lambda p, *s: all_tower_reduce(p, *s), *(batch_fetches.pop( "tower_{}".format(tower_num)) for tower_num in range( len(self.devices))))) for k, v in batch_fetches.items(): if k == LEARNER_STATS_KEY: for k1, v1 in batch_fetches[k].items(): batch_fetches_all_towers[-1][ LEARNER_STATS_KEY][k1] = v1 else: batch_fetches_all_towers[-1][k] = v # Reduce mean across all minibatch SGD steps (axis=0 to keep # all shapes as-is). fetches[policy_id] = tree.map_structure( lambda *s: None if s[0] is None else np.nanmean(s, axis=0), *batch_fetches_all_towers) load_timer.push_units_processed(samples.count) learn_timer.push_units_processed(samples.count) metrics.counters[STEPS_TRAINED_COUNTER] += samples.count metrics.counters[AGENT_STEPS_TRAINED_COUNTER] += samples.agent_steps() metrics.info[LEARNER_INFO] = fetches if self.workers.remote_workers(): with metrics.timers[WORKER_UPDATE_TIMER]: weights = ray.put(self.workers.local_worker().get_weights( self.local_worker.policies_to_train)) for e in self.workers.remote_workers(): e.set_weights.remote(weights, _get_global_vars()) # Also update global vars of the local worker. self.workers.local_worker().set_global_vars(_get_global_vars()) return samples, fetches
# Backward compatibility. TrainTFMultiGPU = MultiGPUTrainOneStep def all_tower_reduce(path, *tower_data): """Reduces stats across towers based on their stats-dict paths.""" if len(path) == 1 and path[0] == "td_error": return np.concatenate(tower_data, axis=0) elif path[-1].startswith("min_"): return np.nanmin(tower_data) elif path[-1].startswith("max_"): return np.nanmax(tower_data) return np.nanmean(tower_data)
[docs]class ComputeGradients: """Callable that computes gradients with respect to the policy loss. This should be used with the .for_each() operator. Examples: >>> grads_op = rollouts.for_each(ComputeGradients(workers)) >>> print(next(grads_op)) {"var_0": ..., ...}, 50 # grads, batch count Updates the LEARNER_INFO info field in the local iterator context. """ def __init__(self, workers: WorkerSet): self.workers = workers def __call__(self, samples: SampleBatchType) -> Tuple[ModelGradients, int]: _check_sample_batch_type(samples) metrics = _get_shared_metrics() with metrics.timers[COMPUTE_GRADS_TIMER]: grad, info = self.workers.local_worker().compute_gradients(samples) metrics.info[LEARNER_INFO] = get_learner_stats(info) return grad, samples.count
[docs]class ApplyGradients: """Callable that applies gradients and updates workers. This should be used with the .for_each() operator. Examples: >>> apply_op = grads_op.for_each(ApplyGradients(workers)) >>> print(next(apply_op)) None Updates the STEPS_TRAINED_COUNTER counter in the local iterator context. """ def __init__(self, workers, policies: List[PolicyID] = frozenset([]), update_all=True): """Creates an ApplyGradients instance. Args: workers (WorkerSet): workers to apply gradients to. update_all (bool): If true, updates all workers. Otherwise, only update the worker that produced the sample batch we are currently processing (i.e., A3C style). """ self.workers = workers self.local_worker = workers.local_worker() self.policies = policies self.update_all = update_all def __call__(self, item: Tuple[ModelGradients, int]) -> None: if not isinstance(item, tuple) or len(item) != 2: raise ValueError( "Input must be a tuple of (grad_dict, count), got {}".format( item)) gradients, count = item metrics = _get_shared_metrics() metrics.counters[STEPS_TRAINED_COUNTER] += count apply_timer = metrics.timers[APPLY_GRADS_TIMER] with apply_timer: self.workers.local_worker().apply_gradients(gradients) apply_timer.push_units_processed(count) # Also update global vars of the local worker. self.workers.local_worker().set_global_vars(_get_global_vars()) if self.update_all: if self.workers.remote_workers(): with metrics.timers[WORKER_UPDATE_TIMER]: weights = ray.put(self.workers.local_worker().get_weights( self.policies or self.local_worker.policies_to_train)) for e in self.workers.remote_workers(): e.set_weights.remote(weights, _get_global_vars()) else: if metrics.current_actor is None: raise ValueError( "Could not find actor to update. When " "update_all=False, `current_actor` must be set " "in the iterator context.") with metrics.timers[WORKER_UPDATE_TIMER]: weights = self.workers.local_worker().get_weights( self.policies or self.local_worker.policies_to_train) metrics.current_actor.set_weights.remote( weights, _get_global_vars())
[docs]class AverageGradients: """Callable that averages the gradients in a batch. This should be used with the .for_each() operator after a set of gradients have been batched with .batch(). Examples: >>> batched_grads = grads_op.batch(32) >>> avg_grads = batched_grads.for_each(AverageGradients()) >>> print(next(avg_grads)) {"var_0": ..., ...}, 1600 # averaged grads, summed batch count """ def __call__(self, gradients: List[Tuple[ModelGradients, int]] ) -> Tuple[ModelGradients, int]: acc = None sum_count = 0 for grad, count in gradients: if acc is None: acc = grad else: acc = [a + b for a, b in zip(acc, grad)] sum_count += count logger.info("Computing average of {} microbatch gradients " "({} samples total)".format(len(gradients), sum_count)) return acc, sum_count
[docs]class UpdateTargetNetwork: """Periodically call policy.update_target() on all trainable policies. This should be used with the .for_each() operator after training step has been taken. Examples: >>> train_op = ParallelRollouts(...).for_each(TrainOneStep(...)) >>> update_op = train_op.for_each( ... UpdateTargetIfNeeded(workers, target_update_freq=500)) >>> print(next(update_op)) None Updates the LAST_TARGET_UPDATE_TS and NUM_TARGET_UPDATES counters in the local iterator context. The value of the last update counter is used to track when we should update the target next. """ def __init__(self, workers: WorkerSet, target_update_freq: int, by_steps_trained: bool = False, policies: List[PolicyID] = frozenset([])): self.workers = workers self.local_worker = workers.local_worker() self.target_update_freq = target_update_freq self.policies = policies if by_steps_trained: self.metric = STEPS_TRAINED_COUNTER else: self.metric = STEPS_SAMPLED_COUNTER def __call__(self, _: Any) -> None: metrics = _get_shared_metrics() cur_ts = metrics.counters[self.metric] last_update = metrics.counters[LAST_TARGET_UPDATE_TS] if cur_ts - last_update > self.target_update_freq: to_update = self.policies or self.local_worker.policies_to_train self.workers.local_worker().foreach_trainable_policy( lambda p, p_id: p_id in to_update and p.update_target()) metrics.counters[NUM_TARGET_UPDATES] += 1 metrics.counters[LAST_TARGET_UPDATE_TS] = cur_ts