示例#1
0
    def __init__(self,
                 env_creator,
                 policy,
                 policy_mapping_fn=None,
                 policies_to_train=None,
                 tf_session_creator=None,
                 rollout_fragment_length=100,
                 batch_mode="truncate_episodes",
                 episode_horizon=None,
                 preprocessor_pref="deepmind",
                 sample_async=False,
                 compress_observations=False,
                 num_envs=1,
                 observation_fn=None,
                 observation_filter="NoFilter",
                 clip_rewards=None,
                 clip_actions=True,
                 env_config=None,
                 model_config=None,
                 policy_config=None,
                 worker_index=0,
                 num_workers=0,
                 monitor_path=None,
                 log_dir=None,
                 log_level=None,
                 callbacks=None,
                 input_creator=lambda ioctx: ioctx.default_sampler_input(),
                 input_evaluation=frozenset([]),
                 output_creator=lambda ioctx: NoopOutput(),
                 remote_worker_envs=False,
                 remote_env_batch_wait_ms=0,
                 soft_horizon=False,
                 no_done_at_end=False,
                 seed=None,
                 extra_python_environs=None,
                 fake_sampler=False):
        """Initialize a rollout worker.

        Arguments:
            env_creator (func): Function that returns a gym.Env given an
                EnvContext wrapped configuration.
            policy (class|dict): Either a class implementing
                Policy, or a dictionary of policy id strings to
                (Policy, obs_space, action_space, config) tuples. If a
                dict is specified, then we are in multi-agent mode and a
                policy_mapping_fn should also be set.
            policy_mapping_fn (func): A function that maps agent ids to
                policy ids in multi-agent mode. This function will be called
                each time a new agent appears in an episode, to bind that agent
                to a policy for the duration of the episode.
            policies_to_train (list): Optional whitelist of policies to train,
                or None for all policies.
            tf_session_creator (func): A function that returns a TF session.
                This is optional and only useful with TFPolicy.
            rollout_fragment_length (int): The target number of env transitions
                to include in each sample batch returned from this worker.
            batch_mode (str): One of the following batch modes:
                "truncate_episodes": Each call to sample() will return a batch
                    of at most `rollout_fragment_length * num_envs` in size.
                    The batch will be exactly
                    `rollout_fragment_length * num_envs` in size if
                    postprocessing does not change batch sizes. Episodes may be
                    truncated in order to meet this size requirement.
                "complete_episodes": Each call to sample() will return a batch
                    of at least `rollout_fragment_length * num_envs` in size.
                    Episodes will not be truncated, but multiple episodes may
                    be packed within one batch to meet the batch size. Note
                    that when `num_envs > 1`, episode steps will be buffered
                    until the episode completes, and hence batches may contain
                    significant amounts of off-policy data.
            episode_horizon (int): Whether to stop episodes at this horizon.
            preprocessor_pref (str): Whether to prefer RLlib preprocessors
                ("rllib") or deepmind ("deepmind") when applicable.
            sample_async (bool): Whether to compute samples asynchronously in
                the background, which improves throughput but can cause samples
                to be slightly off-policy.
            compress_observations (bool): If true, compress the observations.
                They can be decompressed with rllib/utils/compression.
            num_envs (int): If more than one, will create multiple envs
                and vectorize the computation of actions. This has no effect if
                if the env already implements VectorEnv.
            observation_fn (ObservationFunction): Optional multi-agent
                observation function.
            observation_filter (str): Name of observation filter to use.
            clip_rewards (bool): Whether to clip rewards to [-1, 1] prior to
                experience postprocessing. Setting to None means clip for Atari
                only.
            clip_actions (bool): Whether to clip action values to the range
                specified by the policy action space.
            env_config (dict): Config to pass to the env creator.
            model_config (dict): Config to use when creating the policy model.
            policy_config (dict): Config to pass to the policy. In the
                multi-agent case, this config will be merged with the
                per-policy configs specified by `policy`.
            worker_index (int): For remote workers, this should be set to a
                non-zero and unique value. This index is passed to created envs
                through EnvContext so that envs can be configured per worker.
            num_workers (int): For remote workers, how many workers altogether
                have been created?
            monitor_path (str): Write out episode stats and videos to this
                directory if specified.
            log_dir (str): Directory where logs can be placed.
            log_level (str): Set the root log level on creation.
            callbacks (DefaultCallbacks): Custom training callbacks.
            input_creator (func): Function that returns an InputReader object
                for loading previous generated experiences.
            input_evaluation (list): How to evaluate the policy performance.
                This only makes sense to set when the input is reading offline
                data. The possible values include:
                  - "is": the step-wise importance sampling estimator.
                  - "wis": the weighted step-wise is estimator.
                  - "simulation": run the environment in the background, but
                    use this data for evaluation only and never for learning.
            output_creator (func): Function that returns an OutputWriter object
                for saving generated experiences.
            remote_worker_envs (bool): If using num_envs > 1, whether to create
                those new envs in remote processes instead of in the current
                process. This adds overheads, but can make sense if your envs
            remote_env_batch_wait_ms (float): Timeout that remote workers
                are waiting when polling environments. 0 (continue when at
                least one env is ready) is a reasonable default, but optimal
                value could be obtained by measuring your environment
                step / reset and model inference perf.
            soft_horizon (bool): Calculate rewards but don't reset the
                environment when the horizon is hit.
            no_done_at_end (bool): Ignore the done=True at the end of the
                episode and instead record done=False.
            seed (int): Set the seed of both np and tf to this value to
                to ensure each remote worker has unique exploration behavior.
            extra_python_environs (dict): Extra python environments need to
                be set.
            fake_sampler (bool): Use a fake (inf speed) sampler for testing.
        """
        self._original_kwargs = locals().copy()
        del self._original_kwargs["self"]

        global _global_worker
        _global_worker = self

        # set extra environs first
        if extra_python_environs:
            for key, value in extra_python_environs.items():
                os.environ[key] = str(value)

        def gen_rollouts():
            while True:
                yield self.sample()

        ParallelIteratorWorker.__init__(self, gen_rollouts, False)

        policy_config = policy_config or {}
        if (tf and policy_config.get("eager")
                and not policy_config.get("no_eager_on_workers")
                # This eager check is necessary for certain all-framework tests
                # that use tf's eager_mode() context generator.
                and not tf.executing_eagerly()):
            tf.enable_eager_execution()

        if log_level:
            logging.getLogger("ray.rllib").setLevel(log_level)

        if worker_index > 1:
            disable_log_once_globally()  # only need 1 worker to log
        elif log_level == "DEBUG":
            enable_periodic_logging()

        env_context = EnvContext(env_config or {}, worker_index)
        self.policy_config = policy_config
        if callbacks:
            self.callbacks = callbacks()
        else:
            from ray.rllib.agents.callbacks import DefaultCallbacks
            self.callbacks = DefaultCallbacks()
        self.worker_index = worker_index
        self.num_workers = num_workers
        model_config = model_config or {}
        policy_mapping_fn = (policy_mapping_fn
                             or (lambda agent_id: DEFAULT_POLICY_ID))
        if not callable(policy_mapping_fn):
            raise ValueError("Policy mapping function not callable?")
        self.env_creator = env_creator
        self.rollout_fragment_length = rollout_fragment_length * num_envs
        self.batch_mode = batch_mode
        self.compress_observations = compress_observations
        self.preprocessing_enabled = True
        self.last_batch = None
        self.global_vars = None
        self.fake_sampler = fake_sampler

        self.env = _validate_env(env_creator(env_context))
        if isinstance(self.env, MultiAgentEnv) or \
                isinstance(self.env, BaseEnv):

            def wrap(env):
                return env  # we can't auto-wrap these env types
        elif is_atari(self.env) and \
                not model_config.get("custom_preprocessor") and \
                preprocessor_pref == "deepmind":

            # Deepmind wrappers already handle all preprocessing
            self.preprocessing_enabled = False

            if clip_rewards is None:
                clip_rewards = True

            def wrap(env):
                env = wrap_deepmind(
                    env,
                    dim=model_config.get("dim"),
                    framestack=model_config.get("framestack"))
                if monitor_path:
                    from gym import wrappers
                    env = wrappers.Monitor(env, monitor_path, resume=True)
                return env
        else:

            def wrap(env):
                if monitor_path:
                    from gym import wrappers
                    env = wrappers.Monitor(env, monitor_path, resume=True)
                return env

        self.env = wrap(self.env)

        def make_env(vector_index):
            return wrap(
                env_creator(
                    env_context.copy_with_overrides(
                        vector_index=vector_index, remote=remote_worker_envs)))

        self.tf_sess = None
        policy_dict = _validate_and_canonicalize(policy, self.env)
        self.policies_to_train = policies_to_train or list(policy_dict.keys())
        # set numpy and python seed
        if seed is not None:
            np.random.seed(seed)
            random.seed(seed)
            if not hasattr(self.env, "seed"):
                raise ValueError("Env doesn't support env.seed(): {}".format(
                    self.env))
            self.env.seed(seed)
            try:
                assert torch is not None
                torch.manual_seed(seed)
            except AssertionError:
                logger.info("Could not seed torch")
        if _has_tensorflow_graph(policy_dict) and not (tf and
                                                       tf.executing_eagerly()):
            if not tf:
                raise ImportError("Could not import tensorflow")
            with tf.Graph().as_default():
                if tf_session_creator:
                    self.tf_sess = tf_session_creator()
                else:
                    self.tf_sess = tf.Session(
                        config=tf.ConfigProto(
                            gpu_options=tf.GPUOptions(allow_growth=True)))
                with self.tf_sess.as_default():
                    # set graph-level seed
                    if seed is not None:
                        tf.set_random_seed(seed)
                    self.policy_map, self.preprocessors = \
                        self._build_policy_map(policy_dict, policy_config)
            if (ray.is_initialized()
                    and ray.worker._mode() != ray.worker.LOCAL_MODE):
                if not ray.get_gpu_ids():
                    logger.debug(
                        "Creating policy evaluation worker {}".format(
                            worker_index) +
                        " on CPU (please ignore any CUDA init errors)")
                elif not tf.test.is_gpu_available():
                    raise RuntimeError(
                        "GPUs were assigned to this worker by Ray, but "
                        "TensorFlow reports GPU acceleration is disabled. "
                        "This could be due to a bad CUDA or TF installation.")
        else:
            self.policy_map, self.preprocessors = self._build_policy_map(
                policy_dict, policy_config)

        self.multiagent = set(self.policy_map.keys()) != {DEFAULT_POLICY_ID}
        if self.multiagent:
            if not ((isinstance(self.env, MultiAgentEnv)
                     or isinstance(self.env, ExternalMultiAgentEnv))
                    or isinstance(self.env, BaseEnv)):
                raise ValueError(
                    "Have multiple policies {}, but the env ".format(
                        self.policy_map) +
                    "{} is not a subclass of BaseEnv, MultiAgentEnv or "
                    "ExternalMultiAgentEnv?".format(self.env))

        self.filters = {
            policy_id: get_filter(observation_filter,
                                  policy.observation_space.shape)
            for (policy_id, policy) in self.policy_map.items()
        }
        if self.worker_index == 0:
            logger.info("Built filter map: {}".format(self.filters))

        # Always use vector env for consistency even if num_envs = 1
        self.async_env = BaseEnv.to_base_env(
            self.env,
            make_env=make_env,
            num_envs=num_envs,
            remote_envs=remote_worker_envs,
            remote_env_batch_wait_ms=remote_env_batch_wait_ms)
        self.num_envs = num_envs

        if self.batch_mode == "truncate_episodes":
            pack_episodes = True
        elif self.batch_mode == "complete_episodes":
            rollout_fragment_length = float("inf")  # never cut episodes
            pack_episodes = False  # sampler will return 1 episode per poll
        else:
            raise ValueError("Unsupported batch mode: {}".format(
                self.batch_mode))

        self.io_context = IOContext(log_dir, policy_config, worker_index, self)
        self.reward_estimators = []
        for method in input_evaluation:
            if method == "simulation":
                logger.warning(
                    "Requested 'simulation' input evaluation method: "
                    "will discard all sampler outputs and keep only metrics.")
                sample_async = True
            elif method == "is":
                ise = ImportanceSamplingEstimator.create(self.io_context)
                self.reward_estimators.append(ise)
            elif method == "wis":
                wise = WeightedImportanceSamplingEstimator.create(
                    self.io_context)
                self.reward_estimators.append(wise)
            else:
                raise ValueError(
                    "Unknown evaluation method: {}".format(method))

        if sample_async:
            self.sampler = AsyncSampler(
                self,
                self.async_env,
                self.policy_map,
                policy_mapping_fn,
                self.preprocessors,
                self.filters,
                clip_rewards,
                rollout_fragment_length,
                self.callbacks,
                horizon=episode_horizon,
                pack=pack_episodes,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions,
                blackhole_outputs="simulation" in input_evaluation,
                soft_horizon=soft_horizon,
                no_done_at_end=no_done_at_end,
                observation_fn=observation_fn)
            self.sampler.start()
        else:
            self.sampler = SyncSampler(
                self,
                self.async_env,
                self.policy_map,
                policy_mapping_fn,
                self.preprocessors,
                self.filters,
                clip_rewards,
                rollout_fragment_length,
                self.callbacks,
                horizon=episode_horizon,
                pack=pack_episodes,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions,
                soft_horizon=soft_horizon,
                no_done_at_end=no_done_at_end,
                observation_fn=observation_fn)

        self.input_reader = input_creator(self.io_context)
        assert isinstance(self.input_reader, InputReader), self.input_reader
        self.output_writer = output_creator(self.io_context)
        assert isinstance(self.output_writer, OutputWriter), self.output_writer

        logger.debug(
            "Created rollout worker with env {} ({}), policies {}".format(
                self.async_env, self.env, self.policy_map))
示例#2
0
    def __init__(self,
                 env_creator,
                 policy_graph,
                 policy_mapping_fn=None,
                 policies_to_train=None,
                 tf_session_creator=None,
                 batch_steps=100,
                 batch_mode="truncate_episodes",
                 episode_horizon=None,
                 preprocessor_pref="deepmind",
                 sample_async=False,
                 compress_observations=False,
                 num_envs=1,
                 observation_filter="NoFilter",
                 clip_rewards=None,
                 clip_actions=True,
                 env_config=None,
                 model_config=None,
                 policy_config=None,
                 worker_index=0,
                 monitor_path=None,
                 log_dir=None,
                 log_level=None,
                 callbacks=None,
                 input_creator=lambda ioctx: ioctx.default_sampler_input(),
                 input_evaluation=frozenset([]),
                 output_creator=lambda ioctx: NoopOutput(),
                 remote_worker_envs=False,
                 async_remote_worker_envs=False):
        """Initialize a policy evaluator.

        Arguments:
            env_creator (func): Function that returns a gym.Env given an
                EnvContext wrapped configuration.
            policy_graph (class|dict): Either a class implementing
                PolicyGraph, or a dictionary of policy id strings to
                (PolicyGraph, obs_space, action_space, config) tuples. If a
                dict is specified, then we are in multi-agent mode and a
                policy_mapping_fn should also be set.
            policy_mapping_fn (func): A function that maps agent ids to
                policy ids in multi-agent mode. This function will be called
                each time a new agent appears in an episode, to bind that agent
                to a policy for the duration of the episode.
            policies_to_train (list): Optional whitelist of policies to train,
                or None for all policies.
            tf_session_creator (func): A function that returns a TF session.
                This is optional and only useful with TFPolicyGraph.
            batch_steps (int): The target number of env transitions to include
                in each sample batch returned from this evaluator.
            batch_mode (str): One of the following batch modes:
                "truncate_episodes": Each call to sample() will return a batch
                    of at most `batch_steps * num_envs` in size. The batch will
                    be exactly `batch_steps * num_envs` in size if
                    postprocessing does not change batch sizes. Episodes may be
                    truncated in order to meet this size requirement.
                "complete_episodes": Each call to sample() will return a batch
                    of at least `batch_steps * num_envs` in size. Episodes will
                    not be truncated, but multiple episodes may be packed
                    within one batch to meet the batch size. Note that when
                    `num_envs > 1`, episode steps will be buffered until the
                    episode completes, and hence batches may contain
                    significant amounts of off-policy data.
            episode_horizon (int): Whether to stop episodes at this horizon.
            preprocessor_pref (str): Whether to prefer RLlib preprocessors
                ("rllib") or deepmind ("deepmind") when applicable.
            sample_async (bool): Whether to compute samples asynchronously in
                the background, which improves throughput but can cause samples
                to be slightly off-policy.
            compress_observations (bool): If true, compress the observations.
                They can be decompressed with rllib/utils/compression.
            num_envs (int): If more than one, will create multiple envs
                and vectorize the computation of actions. This has no effect if
                if the env already implements VectorEnv.
            observation_filter (str): Name of observation filter to use.
            clip_rewards (bool): Whether to clip rewards to [-1, 1] prior to
                experience postprocessing. Setting to None means clip for Atari
                only.
            clip_actions (bool): Whether to clip action values to the range
                specified by the policy action space.
            env_config (dict): Config to pass to the env creator.
            model_config (dict): Config to use when creating the policy model.
            policy_config (dict): Config to pass to the policy. In the
                multi-agent case, this config will be merged with the
                per-policy configs specified by `policy_graph`.
            worker_index (int): For remote evaluators, this should be set to a
                non-zero and unique value. This index is passed to created envs
                through EnvContext so that envs can be configured per worker.
            monitor_path (str): Write out episode stats and videos to this
                directory if specified.
            log_dir (str): Directory where logs can be placed.
            log_level (str): Set the root log level on creation.
            callbacks (dict): Dict of custom debug callbacks.
            input_creator (func): Function that returns an InputReader object
                for loading previous generated experiences.
            input_evaluation (list): How to evaluate the policy performance.
                This only makes sense to set when the input is reading offline
                data. The possible values include:
                  - "is": the step-wise importance sampling estimator.
                  - "wis": the weighted step-wise is estimator.
                  - "simulation": run the environment in the background, but
                    use this data for evaluation only and never for learning.
            output_creator (func): Function that returns an OutputWriter object
                for saving generated experiences.
            remote_worker_envs (bool): If using num_envs > 1, whether to create
                those new envs in remote processes instead of in the current
                process. This adds overheads, but can make sense if your envs
                are very CPU intensive (e.g., for StarCraft).
            async_remote_worker_envs (bool): Similar to remote_worker_envs,
                but runs the envs asynchronously in the background.
        """

        if log_level:
            logging.getLogger("ray.rllib").setLevel(log_level)

        if worker_index > 1:
            disable_log_once_globally()  # only need 1 evaluator to log
        elif log_level == "DEBUG":
            enable_periodic_logging()

        env_context = EnvContext(env_config or {}, worker_index)
        policy_config = policy_config or {}
        self.policy_config = policy_config
        self.callbacks = callbacks or {}
        self.worker_index = worker_index
        model_config = model_config or {}
        policy_mapping_fn = (policy_mapping_fn
                             or (lambda agent_id: DEFAULT_POLICY_ID))
        if not callable(policy_mapping_fn):
            raise ValueError(
                "Policy mapping function not callable. If you're using Tune, "
                "make sure to escape the function with tune.function() "
                "to prevent it from being evaluated as an expression.")
        self.env_creator = env_creator
        self.sample_batch_size = batch_steps * num_envs
        self.batch_mode = batch_mode
        self.compress_observations = compress_observations
        self.preprocessing_enabled = True

        self.env = _validate_env(env_creator(env_context))
        if isinstance(self.env, MultiAgentEnv) or \
                isinstance(self.env, BaseEnv):

            def wrap(env):
                return env  # we can't auto-wrap these env types
        elif is_atari(self.env) and \
                not model_config.get("custom_preprocessor") and \
                preprocessor_pref == "deepmind":

            # Deepmind wrappers already handle all preprocessing
            self.preprocessing_enabled = False

            if clip_rewards is None:
                clip_rewards = True

            def wrap(env):
                env = wrap_deepmind(env,
                                    dim=model_config.get("dim"),
                                    framestack=model_config.get("framestack"))
                if monitor_path:
                    env = _monitor(env, monitor_path)
                return env
        else:

            def wrap(env):
                if monitor_path:
                    env = _monitor(env, monitor_path)
                return env

        self.env = wrap(self.env)

        def make_env(vector_index):
            return wrap(
                env_creator(
                    env_context.copy_with_overrides(
                        vector_index=vector_index, remote=remote_worker_envs)))

        self.tf_sess = None
        policy_dict = _validate_and_canonicalize(policy_graph, self.env)
        self.policies_to_train = policies_to_train or list(policy_dict.keys())
        if _has_tensorflow_graph(policy_dict):
            if (ray.is_initialized()
                    and ray.worker._mode() != ray.worker.LOCAL_MODE
                    and not ray.get_gpu_ids()):
                logger.info("Creating policy evaluation worker {}".format(
                    worker_index) +
                            " on CPU (please ignore any CUDA init errors)")
            with tf.Graph().as_default():
                if tf_session_creator:
                    self.tf_sess = tf_session_creator()
                else:
                    self.tf_sess = tf.Session(config=tf.ConfigProto(
                        gpu_options=tf.GPUOptions(allow_growth=True)))
                with self.tf_sess.as_default():
                    self.policy_map, self.preprocessors = \
                        self._build_policy_map(policy_dict, policy_config)
        else:
            self.policy_map, self.preprocessors = self._build_policy_map(
                policy_dict, policy_config)

        self.multiagent = set(self.policy_map.keys()) != {DEFAULT_POLICY_ID}
        if self.multiagent:
            if not (isinstance(self.env, MultiAgentEnv)
                    or isinstance(self.env, BaseEnv)):
                raise ValueError(
                    "Have multiple policy graphs {}, but the env ".format(
                        self.policy_map) +
                    "{} is not a subclass of MultiAgentEnv?".format(self.env))

        self.filters = {
            policy_id: get_filter(observation_filter,
                                  policy.observation_space.shape)
            for (policy_id, policy) in self.policy_map.items()
        }
        if self.worker_index == 0:
            logger.info("Built filter map: {}".format(self.filters))

        # Always use vector env for consistency even if num_envs = 1
        self.async_env = BaseEnv.to_base_env(
            self.env,
            make_env=make_env,
            num_envs=num_envs,
            remote_envs=remote_worker_envs,
            async_remote_envs=async_remote_worker_envs)
        self.num_envs = num_envs

        if self.batch_mode == "truncate_episodes":
            unroll_length = batch_steps
            pack_episodes = True
        elif self.batch_mode == "complete_episodes":
            unroll_length = float("inf")  # never cut episodes
            pack_episodes = False  # sampler will return 1 episode per poll
        else:
            raise ValueError("Unsupported batch mode: {}".format(
                self.batch_mode))

        self.io_context = IOContext(log_dir, policy_config, worker_index, self)
        self.reward_estimators = []
        for method in input_evaluation:
            if method == "simulation":
                logger.warning(
                    "Requested 'simulation' input evaluation method: "
                    "will discard all sampler outputs and keep only metrics.")
                sample_async = True
            elif method == "is":
                ise = ImportanceSamplingEstimator.create(self.io_context)
                self.reward_estimators.append(ise)
            elif method == "wis":
                wise = WeightedImportanceSamplingEstimator.create(
                    self.io_context)
                self.reward_estimators.append(wise)
            else:
                raise ValueError(
                    "Unknown evaluation method: {}".format(method))

        if sample_async:
            self.sampler = AsyncSampler(self.async_env,
                                        self.policy_map,
                                        policy_mapping_fn,
                                        self.preprocessors,
                                        self.filters,
                                        clip_rewards,
                                        unroll_length,
                                        self.callbacks,
                                        horizon=episode_horizon,
                                        pack=pack_episodes,
                                        tf_sess=self.tf_sess,
                                        clip_actions=clip_actions,
                                        blackhole_outputs="simulation"
                                        in input_evaluation)
            self.sampler.start()
        else:
            self.sampler = SyncSampler(self.async_env,
                                       self.policy_map,
                                       policy_mapping_fn,
                                       self.preprocessors,
                                       self.filters,
                                       clip_rewards,
                                       unroll_length,
                                       self.callbacks,
                                       horizon=episode_horizon,
                                       pack=pack_episodes,
                                       tf_sess=self.tf_sess,
                                       clip_actions=clip_actions)

        self.input_reader = input_creator(self.io_context)
        assert isinstance(self.input_reader, InputReader), self.input_reader
        self.output_writer = output_creator(self.io_context)
        assert isinstance(self.output_writer, OutputWriter), self.output_writer

        logger.debug("Created evaluator with env {} ({}), policies {}".format(
            self.async_env, self.env, self.policy_map))
示例#3
0
    def __init__(
            self,
            *,
            env_creator: Callable[[EnvContext], EnvType],
            validate_env: Optional[Callable[[EnvType, EnvContext],
                                            None]] = None,
            policy_spec: Union[type, Dict[
                str, Tuple[Optional[type], gym.Space, gym.Space,
                           PartialTrainerConfigDict]]] = None,
            policy_mapping_fn: Optional[Callable[[AgentID], PolicyID]] = None,
            policies_to_train: Optional[List[PolicyID]] = None,
            tf_session_creator: Optional[Callable[[], "tf1.Session"]] = None,
            rollout_fragment_length: int = 100,
            batch_mode: str = "truncate_episodes",
            episode_horizon: int = None,
            preprocessor_pref: str = "deepmind",
            sample_async: bool = False,
            compress_observations: bool = False,
            num_envs: int = 1,
            observation_fn: "ObservationFunction" = None,
            observation_filter: str = "NoFilter",
            clip_rewards: bool = None,
            clip_actions: bool = True,
            env_config: EnvConfigDict = None,
            model_config: ModelConfigDict = None,
            policy_config: TrainerConfigDict = None,
            worker_index: int = 0,
            num_workers: int = 0,
            monitor_path: str = None,
            log_dir: str = None,
            log_level: str = None,
            callbacks: Type["DefaultCallbacks"] = None,
            input_creator: Callable[[
                IOContext
            ], InputReader] = lambda ioctx: ioctx.default_sampler_input(),
            input_evaluation: List[str] = frozenset([]),
            output_creator: Callable[
                [IOContext], OutputWriter] = lambda ioctx: NoopOutput(),
            remote_worker_envs: bool = False,
            remote_env_batch_wait_ms: int = 0,
            soft_horizon: bool = False,
            no_done_at_end: bool = False,
            seed: int = None,
            extra_python_environs: dict = None,
            fake_sampler: bool = False,
            spaces: Optional[Dict[PolicyID, Tuple[gym.spaces.Space,
                                                  gym.spaces.Space]]] = None,
            policy: Union[type, Dict[
                str, Tuple[Optional[type], gym.Space, gym.Space,
                           PartialTrainerConfigDict]]] = None,
    ):
        """Initialize a rollout worker.

        Args:
            env_creator (Callable[[EnvContext], EnvType]): Function that
                returns a gym.Env given an EnvContext wrapped configuration.
            validate_env (Optional[Callable[[EnvType, EnvContext], None]]):
                Optional callable to validate the generated environment (only
                on worker=0).
            policy_spec (Union[type, Dict[str, Tuple[Type[Policy], gym.Space,
                gym.Space, PartialTrainerConfigDict]]]): Either a Policy class
                or a dict of policy id strings to
                (Policy class, obs_space, action_space, config)-tuples. If a
                dict is specified, then we are in multi-agent mode and a
                policy_mapping_fn can also be set (if not, will map all agents
                to DEFAULT_POLICY_ID).
            policy_mapping_fn (Optional[Callable[[AgentID], PolicyID]]): A
                callable that maps agent ids to policy ids in multi-agent mode.
                This function will be called each time a new agent appears in
                an episode, to bind that agent to a policy for the duration of
                the episode. If not provided, will map all agents to
                DEFAULT_POLICY_ID.
            policies_to_train (Optional[List[PolicyID]]): Optional list of
                policies to train, or None for all policies.
            tf_session_creator (Optional[Callable[[], tf1.Session]]): A
                function that returns a TF session. This is optional and only
                useful with TFPolicy.
            rollout_fragment_length (int): The target number of env transitions
                to include in each sample batch returned from this worker.
            batch_mode (str): One of the following batch modes:
                "truncate_episodes": Each call to sample() will return a batch
                    of at most `rollout_fragment_length * num_envs` in size.
                    The batch will be exactly
                    `rollout_fragment_length * num_envs` in size if
                    postprocessing does not change batch sizes. Episodes may be
                    truncated in order to meet this size requirement.
                "complete_episodes": Each call to sample() will return a batch
                    of at least `rollout_fragment_length * num_envs` in size.
                    Episodes will not be truncated, but multiple episodes may
                    be packed within one batch to meet the batch size. Note
                    that when `num_envs > 1`, episode steps will be buffered
                    until the episode completes, and hence batches may contain
                    significant amounts of off-policy data.
            episode_horizon (int): Whether to stop episodes at this horizon.
            preprocessor_pref (str): Whether to prefer RLlib preprocessors
                ("rllib") or deepmind ("deepmind") when applicable.
            sample_async (bool): Whether to compute samples asynchronously in
                the background, which improves throughput but can cause samples
                to be slightly off-policy.
            compress_observations (bool): If true, compress the observations.
                They can be decompressed with rllib/utils/compression.
            num_envs (int): If more than one, will create multiple envs
                and vectorize the computation of actions. This has no effect if
                if the env already implements VectorEnv.
            observation_fn (ObservationFunction): Optional multi-agent
                observation function.
            observation_filter (str): Name of observation filter to use.
            clip_rewards (bool): Whether to clip rewards to [-1, 1] prior to
                experience postprocessing. Setting to None means clip for Atari
                only.
            clip_actions (bool): Whether to clip action values to the range
                specified by the policy action space.
            env_config (EnvConfigDict): Config to pass to the env creator.
            model_config (ModelConfigDict): Config to use when creating the
                policy model.
            policy_config (TrainerConfigDict): Config to pass to the policy.
                In the multi-agent case, this config will be merged with the
                per-policy configs specified by `policy_spec`.
            worker_index (int): For remote workers, this should be set to a
                non-zero and unique value. This index is passed to created envs
                through EnvContext so that envs can be configured per worker.
            num_workers (int): For remote workers, how many workers altogether
                have been created?
            monitor_path (str): Write out episode stats and videos to this
                directory if specified.
            log_dir (str): Directory where logs can be placed.
            log_level (str): Set the root log level on creation.
            callbacks (DefaultCallbacks): Custom training callbacks.
            input_creator (Callable[[IOContext], InputReader]): Function that
                returns an InputReader object for loading previous generated
                experiences.
            input_evaluation (List[str]): How to evaluate the policy
                performance. This only makes sense to set when the input is
                reading offline data. The possible values include:
                  - "is": the step-wise importance sampling estimator.
                  - "wis": the weighted step-wise is estimator.
                  - "simulation": run the environment in the background, but
                    use this data for evaluation only and never for learning.
            output_creator (Callable[[IOContext], OutputWriter]): Function that
                returns an OutputWriter object for saving generated
                experiences.
            remote_worker_envs (bool): If using num_envs > 1, whether to create
                those new envs in remote processes instead of in the current
                process. This adds overheads, but can make sense if your envs
            remote_env_batch_wait_ms (float): Timeout that remote workers
                are waiting when polling environments. 0 (continue when at
                least one env is ready) is a reasonable default, but optimal
                value could be obtained by measuring your environment
                step / reset and model inference perf.
            soft_horizon (bool): Calculate rewards but don't reset the
                environment when the horizon is hit.
            no_done_at_end (bool): Ignore the done=True at the end of the
                episode and instead record done=False.
            seed (int): Set the seed of both np and tf to this value to
                to ensure each remote worker has unique exploration behavior.
            extra_python_environs (dict): Extra python environments need to
                be set.
            fake_sampler (bool): Use a fake (inf speed) sampler for testing.
            spaces (Optional[Dict[PolicyID, Tuple[gym.spaces.Space,
                gym.spaces.Space]]]): An optional space dict mapping policy IDs
                to (obs_space, action_space)-tuples. This is used in case no
                Env is created on this RolloutWorker.
            policy: Obsoleted arg. Use `policy_spec` instead.
        """
        # Deprecated arg.
        if policy is not None:
            deprecation_warning("policy", "policy_spec", error=False)
            policy_spec = policy
        assert policy_spec is not None, "Must provide `policy_spec` when " \
                                        "creating RolloutWorker!"

        self._original_kwargs: dict = locals().copy()
        del self._original_kwargs["self"]

        global _global_worker
        _global_worker = self

        # set extra environs first
        if extra_python_environs:
            for key, value in extra_python_environs.items():
                os.environ[key] = str(value)

        def gen_rollouts():
            while True:
                yield self.sample()

        ParallelIteratorWorker.__init__(self, gen_rollouts, False)

        policy_config: TrainerConfigDict = policy_config or {}
        if (tf1 and policy_config.get("framework") in ["tf2", "tfe"]
                # This eager check is necessary for certain all-framework tests
                # that use tf's eager_mode() context generator.
                and not tf1.executing_eagerly()):
            tf1.enable_eager_execution()

        if log_level:
            logging.getLogger("ray.rllib").setLevel(log_level)

        if worker_index > 1:
            disable_log_once_globally()  # only need 1 worker to log
        elif log_level == "DEBUG":
            enable_periodic_logging()

        env_context = EnvContext(env_config or {}, worker_index)
        self.env_context = env_context
        self.policy_config: TrainerConfigDict = policy_config
        if callbacks:
            self.callbacks: "DefaultCallbacks" = callbacks()
        else:
            from ray.rllib.agents.callbacks import DefaultCallbacks
            self.callbacks: "DefaultCallbacks" = DefaultCallbacks()
        self.worker_index: int = worker_index
        self.num_workers: int = num_workers
        model_config: ModelConfigDict = model_config or {}
        policy_mapping_fn = (policy_mapping_fn
                             or (lambda agent_id: DEFAULT_POLICY_ID))
        if not callable(policy_mapping_fn):
            raise ValueError("Policy mapping function not callable?")
        self.env_creator: Callable[[EnvContext], EnvType] = env_creator
        self.rollout_fragment_length: int = rollout_fragment_length * num_envs
        self.batch_mode: str = batch_mode
        self.compress_observations: bool = compress_observations
        self.preprocessing_enabled: bool = True
        self.last_batch: SampleBatchType = None
        self.global_vars: dict = None
        self.fake_sampler: bool = fake_sampler

        # No Env will be used in this particular worker (not needed).
        if worker_index == 0 and num_workers > 0 and \
                policy_config["create_env_on_driver"] is False:
            self.env = None
        # Create an env for this worker.
        else:
            self.env = _validate_env(env_creator(env_context))
            if validate_env is not None:
                validate_env(self.env, self.env_context)

            if isinstance(self.env, (BaseEnv, MultiAgentEnv)):

                def wrap(env):
                    return env  # we can't auto-wrap these env types

            elif is_atari(self.env) and \
                    not model_config.get("custom_preprocessor") and \
                    preprocessor_pref == "deepmind":

                # Deepmind wrappers already handle all preprocessing.
                self.preprocessing_enabled = False

                # If clip_rewards not explicitly set to False, switch it
                # on here (clip between -1.0 and 1.0).
                if clip_rewards is None:
                    clip_rewards = True

                def wrap(env):
                    env = wrap_deepmind(
                        env,
                        dim=model_config.get("dim"),
                        framestack=model_config.get("framestack"))
                    if monitor_path:
                        from gym import wrappers
                        env = wrappers.Monitor(env, monitor_path, resume=True)
                    return env
            else:

                def wrap(env):
                    if monitor_path:
                        from gym import wrappers
                        env = wrappers.Monitor(env, monitor_path, resume=True)
                    return env

            self.env: EnvType = wrap(self.env)

        def make_env(vector_index):
            return wrap(
                env_creator(
                    env_context.copy_with_overrides(
                        worker_index=worker_index,
                        vector_index=vector_index,
                        remote=remote_worker_envs)))

        self.make_env_fn = make_env

        self.tf_sess = None
        policy_dict = _validate_and_canonicalize(
            policy_spec, self.env, spaces=spaces)
        self.policies_to_train: List[PolicyID] = policies_to_train or list(
            policy_dict.keys())
        self.policy_map: Dict[PolicyID, Policy] = None
        self.preprocessors: Dict[PolicyID, Preprocessor] = None

        # set numpy and python seed
        if seed is not None:
            np.random.seed(seed)
            random.seed(seed)
            if not hasattr(self.env, "seed"):
                logger.info("Env doesn't support env.seed(): {}".format(
                    self.env))
            else:
                self.env.seed(seed)
            try:
                assert torch is not None
                torch.manual_seed(seed)
            except AssertionError:
                logger.info("Could not seed torch")
        if _has_tensorflow_graph(policy_dict) and not (
                tf1 and tf1.executing_eagerly()):
            if not tf1:
                raise ImportError("Could not import tensorflow")
            with tf1.Graph().as_default():
                if tf_session_creator:
                    self.tf_sess = tf_session_creator()
                else:
                    self.tf_sess = tf1.Session(
                        config=tf1.ConfigProto(
                            gpu_options=tf1.GPUOptions(allow_growth=True)))
                with self.tf_sess.as_default():
                    # set graph-level seed
                    if seed is not None:
                        tf1.set_random_seed(seed)
                    self.policy_map, self.preprocessors = \
                        self._build_policy_map(policy_dict, policy_config)
        else:
            self.policy_map, self.preprocessors = self._build_policy_map(
                policy_dict, policy_config)

        if (ray.is_initialized()
                and ray.worker._mode() != ray.worker.LOCAL_MODE):
            # Check available number of GPUs
            if not ray.get_gpu_ids():
                logger.debug("Creating policy evaluation worker {}".format(
                    worker_index) +
                             " on CPU (please ignore any CUDA init errors)")
            elif (policy_config["framework"] in ["tf2", "tf", "tfe"] and
                  not tf.config.experimental.list_physical_devices("GPU")) or \
                    (policy_config["framework"] == "torch" and
                     not torch.cuda.is_available()):
                raise RuntimeError(
                    "GPUs were assigned to this worker by Ray, but "
                    "your DL framework ({}) reports GPU acceleration is "
                    "disabled. This could be due to a bad CUDA- or {} "
                    "installation.".format(policy_config["framework"],
                                           policy_config["framework"]))

        self.multiagent: bool = set(
            self.policy_map.keys()) != {DEFAULT_POLICY_ID}
        if self.multiagent and self.env is not None:
            if not ((isinstance(self.env, MultiAgentEnv)
                     or isinstance(self.env, ExternalMultiAgentEnv))
                    or isinstance(self.env, BaseEnv)):
                raise ValueError(
                    "Have multiple policies {}, but the env ".format(
                        self.policy_map) +
                    "{} is not a subclass of BaseEnv, MultiAgentEnv or "
                    "ExternalMultiAgentEnv?".format(self.env))

        self.filters: Dict[PolicyID, Filter] = {
            policy_id: get_filter(observation_filter,
                                  policy.observation_space.shape)
            for (policy_id, policy) in self.policy_map.items()
        }
        if self.worker_index == 0:
            logger.info("Built filter map: {}".format(self.filters))

        self.num_envs: int = num_envs

        if self.env is None:
            self.async_env = None
        elif "custom_vector_env" in policy_config:
            custom_vec_wrapper = policy_config["custom_vector_env"]
            self.async_env = custom_vec_wrapper(self.env)
        else:
            # Always use vector env for consistency even if num_envs = 1.
            self.async_env: BaseEnv = BaseEnv.to_base_env(
                self.env,
                make_env=make_env,
                num_envs=num_envs,
                remote_envs=remote_worker_envs,
                remote_env_batch_wait_ms=remote_env_batch_wait_ms)

        # `truncate_episodes`: Allow a batch to contain more than one episode
        # (fragments) and always make the batch `rollout_fragment_length`
        # long.
        if self.batch_mode == "truncate_episodes":
            pack = True
        # `complete_episodes`: Never cut episodes and sampler will return
        # exactly one (complete) episode per poll.
        elif self.batch_mode == "complete_episodes":
            rollout_fragment_length = float("inf")
            pack = False
        else:
            raise ValueError("Unsupported batch mode: {}".format(
                self.batch_mode))

        self.io_context: IOContext = IOContext(log_dir, policy_config,
                                               worker_index, self)
        self.reward_estimators: List[OffPolicyEstimator] = []
        for method in input_evaluation:
            if method == "simulation":
                logger.warning(
                    "Requested 'simulation' input evaluation method: "
                    "will discard all sampler outputs and keep only metrics.")
                sample_async = True
            elif method == "is":
                ise = ImportanceSamplingEstimator.create(self.io_context)
                self.reward_estimators.append(ise)
            elif method == "wis":
                wise = WeightedImportanceSamplingEstimator.create(
                    self.io_context)
                self.reward_estimators.append(wise)
            else:
                raise ValueError(
                    "Unknown evaluation method: {}".format(method))

        if self.env is None:
            self.sampler = None
        elif sample_async:
            self.sampler = AsyncSampler(
                worker=self,
                env=self.async_env,
                policies=self.policy_map,
                policy_mapping_fn=policy_mapping_fn,
                preprocessors=self.preprocessors,
                obs_filters=self.filters,
                clip_rewards=clip_rewards,
                rollout_fragment_length=rollout_fragment_length,
                callbacks=self.callbacks,
                horizon=episode_horizon,
                multiple_episodes_in_batch=pack,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions,
                blackhole_outputs="simulation" in input_evaluation,
                soft_horizon=soft_horizon,
                no_done_at_end=no_done_at_end,
                observation_fn=observation_fn,
                _use_trajectory_view_api=policy_config.get(
                    "_use_trajectory_view_api", False))
            # Start the Sampler thread.
            self.sampler.start()
        else:
            self.sampler = SyncSampler(
                worker=self,
                env=self.async_env,
                policies=self.policy_map,
                policy_mapping_fn=policy_mapping_fn,
                preprocessors=self.preprocessors,
                obs_filters=self.filters,
                clip_rewards=clip_rewards,
                rollout_fragment_length=rollout_fragment_length,
                callbacks=self.callbacks,
                horizon=episode_horizon,
                multiple_episodes_in_batch=pack,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions,
                soft_horizon=soft_horizon,
                no_done_at_end=no_done_at_end,
                observation_fn=observation_fn,
                _use_trajectory_view_api=policy_config.get(
                    "_use_trajectory_view_api", False))

        self.input_reader: InputReader = input_creator(self.io_context)
        self.output_writer: OutputWriter = output_creator(self.io_context)

        logger.debug(
            "Created rollout worker with env {} ({}), policies {}".format(
                self.async_env, self.env, self.policy_map))
示例#4
0
    def __init__(self,
                 env_creator,
                 policy_graph,
                 policy_mapping_fn=None,
                 policies_to_train=None,
                 tf_session_creator=None,
                 batch_steps=100,
                 batch_mode="truncate_episodes",
                 episode_horizon=None,
                 preprocessor_pref="deepmind",
                 sample_async=False,
                 compress_observations=False,
                 num_envs=1,
                 observation_filter="NoFilter",
                 clip_rewards=None,
                 clip_actions=True,
                 env_config=None,
                 model_config=None,
                 policy_config=None,
                 worker_index=0,
                 monitor_path=None,
                 log_dir=None,
                 log_level=None,
                 callbacks=None,
                 input_creator=lambda ioctx: ioctx.default_sampler_input(),
                 input_evaluation=frozenset([]),
                 output_creator=lambda ioctx: NoopOutput(),
                 remote_worker_envs=False,
                 async_remote_worker_envs=False):
        """Initialize a policy evaluator.

        Arguments:
            env_creator (func): Function that returns a gym.Env given an
                EnvContext wrapped configuration.
            policy_graph (class|dict): Either a class implementing
                PolicyGraph, or a dictionary of policy id strings to
                (PolicyGraph, obs_space, action_space, config) tuples. If a
                dict is specified, then we are in multi-agent mode and a
                policy_mapping_fn should also be set.
            policy_mapping_fn (func): A function that maps agent ids to
                policy ids in multi-agent mode. This function will be called
                each time a new agent appears in an episode, to bind that agent
                to a policy for the duration of the episode.
            policies_to_train (list): Optional whitelist of policies to train,
                or None for all policies.
            tf_session_creator (func): A function that returns a TF session.
                This is optional and only useful with TFPolicyGraph.
            batch_steps (int): The target number of env transitions to include
                in each sample batch returned from this evaluator.
            batch_mode (str): One of the following batch modes:
                "truncate_episodes": Each call to sample() will return a batch
                    of at most `batch_steps * num_envs` in size. The batch will
                    be exactly `batch_steps * num_envs` in size if
                    postprocessing does not change batch sizes. Episodes may be
                    truncated in order to meet this size requirement.
                "complete_episodes": Each call to sample() will return a batch
                    of at least `batch_steps * num_envs` in size. Episodes will
                    not be truncated, but multiple episodes may be packed
                    within one batch to meet the batch size. Note that when
                    `num_envs > 1`, episode steps will be buffered until the
                    episode completes, and hence batches may contain
                    significant amounts of off-policy data.
            episode_horizon (int): Whether to stop episodes at this horizon.
            preprocessor_pref (str): Whether to prefer RLlib preprocessors
                ("rllib") or deepmind ("deepmind") when applicable.
            sample_async (bool): Whether to compute samples asynchronously in
                the background, which improves throughput but can cause samples
                to be slightly off-policy.
            compress_observations (bool): If true, compress the observations.
                They can be decompressed with rllib/utils/compression.
            num_envs (int): If more than one, will create multiple envs
                and vectorize the computation of actions. This has no effect if
                if the env already implements VectorEnv.
            observation_filter (str): Name of observation filter to use.
            clip_rewards (bool): Whether to clip rewards to [-1, 1] prior to
                experience postprocessing. Setting to None means clip for Atari
                only.
            clip_actions (bool): Whether to clip action values to the range
                specified by the policy action space.
            env_config (dict): Config to pass to the env creator.
            model_config (dict): Config to use when creating the policy model.
            policy_config (dict): Config to pass to the policy. In the
                multi-agent case, this config will be merged with the
                per-policy configs specified by `policy_graph`.
            worker_index (int): For remote evaluators, this should be set to a
                non-zero and unique value. This index is passed to created envs
                through EnvContext so that envs can be configured per worker.
            monitor_path (str): Write out episode stats and videos to this
                directory if specified.
            log_dir (str): Directory where logs can be placed.
            log_level (str): Set the root log level on creation.
            callbacks (dict): Dict of custom debug callbacks.
            input_creator (func): Function that returns an InputReader object
                for loading previous generated experiences.
            input_evaluation (list): How to evaluate the policy performance.
                This only makes sense to set when the input is reading offline
                data. The possible values include:
                  - "is": the step-wise importance sampling estimator.
                  - "wis": the weighted step-wise is estimator.
                  - "simulation": run the environment in the background, but
                    use this data for evaluation only and never for learning.
            output_creator (func): Function that returns an OutputWriter object
                for saving generated experiences.
            remote_worker_envs (bool): If using num_envs > 1, whether to create
                those new envs in remote processes instead of in the current
                process. This adds overheads, but can make sense if your envs
                are very CPU intensive (e.g., for StarCraft).
            async_remote_worker_envs (bool): Similar to remote_worker_envs,
                but runs the envs asynchronously in the background.
        """

        if log_level:
            logging.getLogger("ray.rllib").setLevel(log_level)

        env_context = EnvContext(env_config or {}, worker_index)
        policy_config = policy_config or {}
        self.policy_config = policy_config
        self.callbacks = callbacks or {}
        model_config = model_config or {}
        policy_mapping_fn = (policy_mapping_fn
                             or (lambda agent_id: DEFAULT_POLICY_ID))
        if not callable(policy_mapping_fn):
            raise ValueError(
                "Policy mapping function not callable. If you're using Tune, "
                "make sure to escape the function with tune.function() "
                "to prevent it from being evaluated as an expression.")
        self.env_creator = env_creator
        self.sample_batch_size = batch_steps * num_envs
        self.batch_mode = batch_mode
        self.compress_observations = compress_observations
        self.preprocessing_enabled = True

        self.env = _validate_env(env_creator(env_context))
        if isinstance(self.env, MultiAgentEnv) or \
                isinstance(self.env, BaseEnv):

            def wrap(env):
                return env  # we can't auto-wrap these env types
        elif is_atari(self.env) and \
                not model_config.get("custom_preprocessor") and \
                preprocessor_pref == "deepmind":

            # Deepmind wrappers already handle all preprocessing
            self.preprocessing_enabled = False

            if clip_rewards is None:
                clip_rewards = True

            def wrap(env):
                env = wrap_deepmind(
                    env,
                    dim=model_config.get("dim"),
                    framestack=model_config.get("framestack"))
                if monitor_path:
                    env = _monitor(env, monitor_path)
                return env
        else:

            def wrap(env):
                if monitor_path:
                    env = _monitor(env, monitor_path)
                return env

        self.env = wrap(self.env)

        def make_env(vector_index):
            return wrap(
                env_creator(
                    env_context.copy_with_overrides(
                        vector_index=vector_index, remote=remote_worker_envs)))

        self.tf_sess = None
        policy_dict = _validate_and_canonicalize(policy_graph, self.env)
        self.policies_to_train = policies_to_train or list(policy_dict.keys())
        if _has_tensorflow_graph(policy_dict):
            if (ray.is_initialized()
                    and ray.worker._mode() != ray.worker.LOCAL_MODE
                    and not ray.get_gpu_ids()):
                logger.info("Creating policy evaluation worker {}".format(
                    worker_index) +
                            " on CPU (please ignore any CUDA init errors)")
            with tf.Graph().as_default():
                if tf_session_creator:
                    self.tf_sess = tf_session_creator()
                else:
                    self.tf_sess = tf.Session(
                        config=tf.ConfigProto(
                            gpu_options=tf.GPUOptions(allow_growth=True)))
                with self.tf_sess.as_default():
                    self.policy_map, self.preprocessors = \
                        self._build_policy_map(policy_dict, policy_config)
        else:
            self.policy_map, self.preprocessors = self._build_policy_map(
                policy_dict, policy_config)

        self.multiagent = set(self.policy_map.keys()) != {DEFAULT_POLICY_ID}
        if self.multiagent:
            if not (isinstance(self.env, MultiAgentEnv)
                    or isinstance(self.env, BaseEnv)):
                raise ValueError(
                    "Have multiple policy graphs {}, but the env ".format(
                        self.policy_map) +
                    "{} is not a subclass of MultiAgentEnv?".format(self.env))

        self.filters = {
            policy_id: get_filter(observation_filter,
                                  policy.observation_space.shape)
            for (policy_id, policy) in self.policy_map.items()
        }

        # Always use vector env for consistency even if num_envs = 1
        self.async_env = BaseEnv.to_base_env(
            self.env,
            make_env=make_env,
            num_envs=num_envs,
            remote_envs=remote_worker_envs,
            async_remote_envs=async_remote_worker_envs)
        self.num_envs = num_envs

        if self.batch_mode == "truncate_episodes":
            unroll_length = batch_steps
            pack_episodes = True
        elif self.batch_mode == "complete_episodes":
            unroll_length = float("inf")  # never cut episodes
            pack_episodes = False  # sampler will return 1 episode per poll
        else:
            raise ValueError("Unsupported batch mode: {}".format(
                self.batch_mode))

        self.io_context = IOContext(log_dir, policy_config, worker_index, self)
        self.reward_estimators = []
        for method in input_evaluation:
            if method == "simulation":
                logger.warning(
                    "Requested 'simulation' input evaluation method: "
                    "will discard all sampler outputs and keep only metrics.")
                sample_async = True
            elif method == "is":
                ise = ImportanceSamplingEstimator.create(self.io_context)
                self.reward_estimators.append(ise)
            elif method == "wis":
                wise = WeightedImportanceSamplingEstimator.create(
                    self.io_context)
                self.reward_estimators.append(wise)
            else:
                raise ValueError(
                    "Unknown evaluation method: {}".format(method))

        if sample_async:
            self.sampler = AsyncSampler(
                self.async_env,
                self.policy_map,
                policy_mapping_fn,
                self.preprocessors,
                self.filters,
                clip_rewards,
                unroll_length,
                self.callbacks,
                horizon=episode_horizon,
                pack=pack_episodes,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions,
                blackhole_outputs="simulation" in input_evaluation)
            self.sampler.start()
        else:
            self.sampler = SyncSampler(
                self.async_env,
                self.policy_map,
                policy_mapping_fn,
                self.preprocessors,
                self.filters,
                clip_rewards,
                unroll_length,
                self.callbacks,
                horizon=episode_horizon,
                pack=pack_episodes,
                tf_sess=self.tf_sess,
                clip_actions=clip_actions)

        self.input_reader = input_creator(self.io_context)
        assert isinstance(self.input_reader, InputReader), self.input_reader
        self.output_writer = output_creator(self.io_context)
        assert isinstance(self.output_writer, OutputWriter), self.output_writer

        logger.debug("Created evaluator with env {} ({}), policies {}".format(
            self.async_env, self.env, self.policy_map))