Source code for ray.rllib.execution.rollout_ops

import logging
from typing import List, Tuple
import time

from ray.util.iter import from_actors, LocalIterator
from ray.util.iter_metrics import SharedMetrics
from ray.rllib.evaluation.metrics import get_learner_stats
from ray.rllib.evaluation.rollout_worker import get_global_worker
from ray.rllib.evaluation.worker_set import WorkerSet
from ray.rllib.execution.common import STEPS_SAMPLED_COUNTER, LEARNER_INFO, \
    SAMPLE_TIMER, GRAD_WAIT_TIMER, _check_sample_batch_type, \
from ray.rllib.policy.sample_batch import SampleBatch, DEFAULT_POLICY_ID, \
from ray.rllib.utils.sgd import standardized
from ray.rllib.utils.typing import PolicyID, SampleBatchType, ModelGradients

logger = logging.getLogger(__name__)

[docs]def ParallelRollouts(workers: WorkerSet, *, mode="bulk_sync", num_async=1) -> LocalIterator[SampleBatch]: """Operator to collect experiences in parallel from rollout workers. If there are no remote workers, experiences will be collected serially from the local worker instance instead. Args: workers (WorkerSet): set of rollout workers to use. mode (str): One of 'async', 'bulk_sync', 'raw'. In 'async' mode, batches are returned as soon as they are computed by rollout workers with no order guarantees. In 'bulk_sync' mode, we collect one batch from each worker and concatenate them together into a large batch to return. In 'raw' mode, the ParallelIterator object is returned directly and the caller is responsible for implementing gather and updating the timesteps counter. num_async (int): In async mode, the max number of async requests in flight per actor. Returns: A local iterator over experiences collected in parallel. Examples: >>> rollouts = ParallelRollouts(workers, mode="async") >>> batch = next(rollouts) >>> print(batch.count) 50 # config.rollout_fragment_length >>> rollouts = ParallelRollouts(workers, mode="bulk_sync") >>> batch = next(rollouts) >>> print(batch.count) 200 # config.rollout_fragment_length * config.num_workers Updates the STEPS_SAMPLED_COUNTER counter in the local iterator context. """ # Ensure workers are initially in sync. workers.sync_weights() def report_timesteps(batch): metrics = _get_shared_metrics() metrics.counters[STEPS_SAMPLED_COUNTER] += batch.count return batch if not workers.remote_workers(): # Handle the serial sampling case. def sampler(_): while True: yield workers.local_worker().sample() return (LocalIterator(sampler, SharedMetrics()) .for_each(report_timesteps)) # Create a parallel iterator over generated experiences. rollouts = from_actors(workers.remote_workers()) if mode == "bulk_sync": return rollouts \ .batch_across_shards() \ .for_each(lambda batches: SampleBatch.concat_samples(batches)) \ .for_each(report_timesteps) elif mode == "async": return rollouts.gather_async( num_async=num_async).for_each(report_timesteps) elif mode == "raw": return rollouts else: raise ValueError("mode must be one of 'bulk_sync', 'async', 'raw', " "got '{}'".format(mode))
[docs]def AsyncGradients( workers: WorkerSet) -> LocalIterator[Tuple[ModelGradients, int]]: """Operator to compute gradients in parallel from rollout workers. Args: workers (WorkerSet): set of rollout workers to use. Returns: A local iterator over policy gradients computed on rollout workers. Examples: >>> grads_op = AsyncGradients(workers) >>> print(next(grads_op)) {"var_0": ..., ...}, 50 # grads, batch count Updates the STEPS_SAMPLED_COUNTER counter and LEARNER_INFO field in the local iterator context. """ # Ensure workers are initially in sync. workers.sync_weights() # This function will be applied remotely on the workers. def samples_to_grads(samples): return get_global_worker().compute_gradients(samples), samples.count # Record learner metrics and pass through (grads, count). class record_metrics: def _on_fetch_start(self): self.fetch_start_time = time.perf_counter() def __call__(self, item): (grads, info), count = item metrics = _get_shared_metrics() metrics.counters[STEPS_SAMPLED_COUNTER] += count[LEARNER_INFO] = get_learner_stats(info) metrics.timers[GRAD_WAIT_TIMER].push(time.perf_counter() - self.fetch_start_time) return grads, count rollouts = from_actors(workers.remote_workers()) grads = rollouts.for_each(samples_to_grads) return grads.gather_async().for_each(record_metrics())
[docs]class ConcatBatches: """Callable used to merge batches into larger batches for training. This should be used with the .combine() operator. Examples: >>> rollouts = ParallelRollouts(...) >>> rollouts = rollouts.combine(ConcatBatches(min_batch_size=10000)) >>> print(next(rollouts).count) 10000 """ def __init__(self, min_batch_size: int): self.min_batch_size = min_batch_size self.buffer = [] self.count = 0 self.batch_start_time = None def _on_fetch_start(self): if self.batch_start_time is None: self.batch_start_time = time.perf_counter() def __call__(self, batch: SampleBatchType) -> List[SampleBatchType]: _check_sample_batch_type(batch) self.buffer.append(batch) self.count += batch.count if self.count >= self.min_batch_size: if self.count > self.min_batch_size * 2:"Collected more training samples than expected " "(actual={}, expected={}). ".format( self.count, self.min_batch_size) + "This may be because you have many workers or " "long episodes in 'complete_episodes' batch mode.") out = SampleBatch.concat_samples(self.buffer) timer = _get_shared_metrics().timers[SAMPLE_TIMER] timer.push(time.perf_counter() - self.batch_start_time) timer.push_units_processed(self.count) self.batch_start_time = None self.buffer = [] self.count = 0 return [out] return []
[docs]class SelectExperiences: """Callable used to select experiences from a MultiAgentBatch. This should be used with the .for_each() operator. Examples: >>> rollouts = ParallelRollouts(...) >>> rollouts = rollouts.for_each(SelectExperiences(["pol1", "pol2"])) >>> print(next(rollouts).policy_batches.keys()) {"pol1", "pol2"} """ def __init__(self, policy_ids: List[PolicyID]): assert isinstance(policy_ids, list), policy_ids self.policy_ids = policy_ids def __call__(self, samples: SampleBatchType) -> SampleBatchType: _check_sample_batch_type(samples) if isinstance(samples, MultiAgentBatch): samples = MultiAgentBatch({ k: v for k, v in samples.policy_batches.items() if k in self.policy_ids }, samples.count) return samples
[docs]class StandardizeFields: """Callable used to standardize fields of batches. This should be used with the .for_each() operator. Note that the input may be mutated by this operator for efficiency. Examples: >>> rollouts = ParallelRollouts(...) >>> rollouts = rollouts.for_each(StandardizeFields(["advantages"])) >>> print(np.std(next(rollouts)["advantages"])) 1.0 """ def __init__(self, fields: List[str]): self.fields = fields def __call__(self, samples: SampleBatchType) -> SampleBatchType: _check_sample_batch_type(samples) wrapped = False if isinstance(samples, SampleBatch): samples = MultiAgentBatch({ DEFAULT_POLICY_ID: samples }, samples.count) wrapped = True for policy_id in samples.policy_batches: batch = samples.policy_batches[policy_id] for field in self.fields: batch[field] = standardized(batch[field]) if wrapped: samples = samples.policy_batches[DEFAULT_POLICY_ID] return samples