[RLlib] Cleanup examples folder #15: Add example script for policy (RLModule) inference w/ ConnectorV2.

rllib/BUILD

@@ -2504,6 +2504,15 @@ py_test(
     args = ["--enable-new-api-stack", "--stop-reward=100.0"]
 )
 
+py_test(
+    name = "examples/inference/policy_inference_after_training_w_connector",
+    main = "examples/inference/policy_inference_after_training_w_connector.py",
+    tags = ["team:rllib", "exclusive", "examples"],
+    size = "medium",
+    srcs = ["examples/inference/policy_inference_after_training_w_connector.py"],
+    args = ["--enable-new-api-stack", "--stop-reward=150.0"]
+)
+
 #@OldAPIStack
 py_test(
     name = "examples/inference/policy_inference_after_training_with_attention_tf",

rllib/connectors/connector_pipeline_v2.py

@@ -36,6 +36,20 @@ def __init__(
         connectors: Optional[List[ConnectorV2]] = None,
         **kwargs,
     ):
+        """Initializes a ConnectorPipelineV2 instance.
+
+        Args:
+            input_observation_space: The (optional) input observation space for this
+                connector piece. This is the space coming from a previous connector
+                piece in the (env-to-module or learner) pipeline or is directly
+                defined within the gym.Env.
+            input_action_space: The (optional) input action space for this connector
+                piece. This is the space coming from a previous connector piece in the
+                (module-to-env) pipeline or is directly defined within the gym.Env.
+            connectors: A list of individual ConnectorV2 pieces to be added to this
+                pipeline during construction. Note that you can always add (or remove)
+                more ConnectorV2 pieces later on the fly.
+        """
         self.connectors = connectors or []
 
         super().__init__(input_observation_space, input_action_space, **kwargs)
@@ -48,6 +62,7 @@ def __len__(self):
     @override(ConnectorV2)
     def __call__(
         self,
+        *,
         rl_module: RLModule,
         data: Any,
         episodes: List[EpisodeType],
@@ -60,6 +75,7 @@ def __call__(
         Each connector piece receives as input the output of the previous connector
         piece in the pipeline.
         """
+        shared_data = shared_data if shared_data is not None else {}
         # Loop through connector pieces and call each one with the output of the
         # previous one. Thereby, time each connector piece's call.
         for connector in self.connectors:

rllib/connectors/env_to_module/env_to_module_pipeline.py

@@ -27,6 +27,6 @@ def __call__(
             data=data if data is not None else {},
             episodes=episodes,
             explore=explore,
-            shared_data=shared_data,
+            shared_data=shared_data if shared_data is not None else {},
             **kwargs,
         )

rllib/examples/inference/policy_inference_after_training_w_connector.py

@@ -0,0 +1,265 @@
+"""Example on how to compute actions in production on an already trained policy.
+
+This example uses a more complex setup including a gymnasium environment, an
+RLModule (one or more neural networks/policies), an env-to-module/module-to-env
+ConnectorV2 pair, and an Episode object to store the ongoing episode in.
+The RLModule contains an LSTM that requires its own previous STATE_OUT as new input
+at every episode step to compute a new action.
+
+This example shows ..
+  - .. how to use an already existing checkpoint to extract a single-agent RLModule
+  from (our policy network).
+  - .. how to setup this recovered policy net for action computations (with or without
+  using exploration).
+  - .. how to create a more complex env-loop in which the action-computing RLModule
+  requires its own previous state outputs as new input and how to use RLlib's Episode
+  APIs to achieve this.
+
+
+How to run this script
+----------------------
+`python [script file name].py --enable-new-api-stack --stop-reward=200.0`
+
+Use the `--explore-during-inference` option to switch on exploratory behavior
+during inference. Normally, you should not explore during inference, though,
+unless your environment has a stochastic optimal solution.
+Use the `--num-episodes-during-inference=[int]` option to set the number of
+episodes to run through during the inference phase using the restored RLModule.
+
+For debugging, use the following additional command line options
+`--no-tune --num-env-runners=0`
+which should allow you to set breakpoints anywhere in the RLlib code and
+have the execution stop there for inspection and debugging.
+
+Note that the shown GPU settings in this script also work in case you are not
+running via tune, but instead are using the `--no-tune` command line option.
+
+For logging to your WandB account, use:
+`--wandb-key=[your WandB API key] --wandb-project=[some project name]
+--wandb-run-name=[optional: WandB run name (within the defined project)]`
+
+You can visualize experiment results in ~/ray_results using TensorBoard.
+
+
+Results to expect
+-----------------
+
+For the training step - depending on your `--stop-reward` setting, you should see
+something similar to this:
+
+Number of trials: 1/1 (1 TERMINATED)
++--------------------------------+------------+-----------------+--------+
+| Trial name                     | status     | loc             |   iter |
+|                                |            |                 |        |
+|--------------------------------+------------+-----------------+--------+
+| PPO_stateless-cart_cc890_00000 | TERMINATED | 127.0.0.1:72238 |      7 |
++--------------------------------+------------+-----------------+--------+
++------------------+------------------------+------------------------+
+|   total time (s) |   num_env_steps_sample |   num_env_steps_traine |
+|                  |             d_lifetime |             d_lifetime |
++------------------+------------------------+------------------------+
+|          31.9655 |                  28000 |                  28000 |
++------------------+------------------------+------------------------+
+
+Then, after restoring the RLModule for the inference phase, your output should
+look similar to:
+
+Training completed. Creating an env-loop for inference ...
+Env ...
+Env-to-module ConnectorV2 ...
+RLModule restored ...
+Module-to-env ConnectorV2 ...
+Episode done: Total reward = 103.0
+Episode done: Total reward = 90.0
+Episode done: Total reward = 100.0
+Episode done: Total reward = 111.0
+Episode done: Total reward = 85.0
+Episode done: Total reward = 90.0
+Episode done: Total reward = 100.0
+Episode done: Total reward = 102.0
+Episode done: Total reward = 97.0
+Episode done: Total reward = 81.0
+Done performing action inference through 10 Episodes
+"""
+import os
+
+from ray.rllib.connectors.env_to_module import (
+    EnvToModulePipeline,
+    AddObservationsFromEpisodesToBatch,
+    AddStatesFromEpisodesToBatch,
+    BatchIndividualItems,
+    NumpyToTensor,
+)
+from ray.rllib.core import DEFAULT_MODULE_ID
+from ray.rllib.core.columns import Columns
+from ray.rllib.core.rl_module.rl_module import RLModule
+from ray.rllib.env.single_agent_episode import SingleAgentEpisode
+from ray.rllib.examples.envs.classes.stateless_cartpole import StatelessCartPole
+from ray.rllib.utils.framework import try_import_torch
+from ray.rllib.utils.metrics import (
+    ENV_RUNNER_RESULTS,
+    EPISODE_RETURN_MEAN,
+)
+from ray.rllib.utils.test_utils import (
+    add_rllib_example_script_args,
+    run_rllib_example_script_experiment,
+)
+from ray.tune.registry import get_trainable_cls, register_env
+
+torch, _ = try_import_torch()
+
+
+def _env_creator(cfg):
+    return StatelessCartPole(cfg)
+
+
+register_env("stateless-cart", _env_creator)
+
+
+parser = add_rllib_example_script_args(default_reward=200.0)
+parser.set_defaults(
+    # Make sure that - by default - we produce checkpoints during training.
+    checkpoint_freq=1,
+    checkpoint_at_end=True,
+    # Use StatelessCartPole by default.
+    env="stateless-cart",
+)
+parser.add_argument(
+    "--explore-during-inference",
+    action="store_true",
+    help="Whether the trained policy should use exploration during action "
+    "inference.",
+)
+parser.add_argument(
+    "--num-episodes-during-inference",
+    type=int,
+    default=10,
+    help="Number of episodes to do inference over (after restoring from a checkpoint).",
+)
+
+
+if __name__ == "__main__":
+    args = parser.parse_args()
+
+    assert (
+        args.enable_new_api_stack
+    ), "Must set --enable-new-api-stack when running this script!"
+
+    base_config = (
+        get_trainable_cls(args.algo)
+        .get_default_config()
+        .training(
+            num_sgd_iter=6,
+            lr=0.0003,
+            vf_loss_coeff=0.01,
+        )
+        # Add an LSTM setup to the default RLModule used.
+        .rl_module(model_config_dict={"use_lstm": True})
+    )
+
+    print("Training LSTM-policy until desired reward/timesteps/iterations. ...")
+    results = run_rllib_example_script_experiment(base_config, args)
+
+    print("Training completed. Creating an env-loop for inference ...")
+
+    print("Env ...")
+    env = _env_creator(base_config.env_config)
+
+    # We build the env-to-module pipeline here manually, but feel also free to build it
+    # through the even easier:
+    # `env_to_module = base_config.build_env_to_module_connector(env=env)`, which will
+    # automatically add all default pieces necessary (for example the
+    # `AddStatesFromEpisodesToBatch` component b/c we are using a stateful RLModule
+    # here).
+    print("Env-to-module ConnectorV2 ...")
+    env_to_module = EnvToModulePipeline(
+        input_observation_space=env.observation_space,
+        input_action_space=env.action_space,
+        connectors=[
+            AddObservationsFromEpisodesToBatch(),
+            AddStatesFromEpisodesToBatch(),
+            BatchIndividualItems(),
+            NumpyToTensor(),
+        ],
+    )
+
+    # Create the RLModule.
+    # Get the last checkpoint from the above training run.
+    best_result = results.get_best_result(
+        metric=f"{ENV_RUNNER_RESULTS}/{EPISODE_RETURN_MEAN}", mode="max"
+    )
+    # Create new Algorithm and restore its state from the last checkpoint.
+    rl_module = RLModule.from_checkpoint(
+        os.path.join(
+            best_result.checkpoint.path,
+            "learner",
+            "module_state",
+            DEFAULT_MODULE_ID,
+        )
+    )
+    print("RLModule restored ...")
+
+    # For the module-to-env pipeline, we will use the convenient config utility.
+    print("Module-to-env ConnectorV2 ...")
+    module_to_env = base_config.build_module_to_env_connector(env=env)
+
+    # Now our setup is complete:
+    # [gym.Env] -> env-to-module -> [RLModule] -> module-to-env -> [gym.Env] ... repeat
+    num_episodes = 0
+
+    obs, _ = env.reset()
+    episode = SingleAgentEpisode(
+        observations=[obs],
+        observation_space=env.observation_space,
+        action_space=env.action_space,
+    )
+
+    while num_episodes < args.num_episodes_during_inference:
+        shared_data = {}
+        input_dict = env_to_module(
+            episodes=[episode],  # ConnectorV2 pipelines operate on lists of episodes.
+            rl_module=rl_module,
+            explore=args.explore_during_inference,
+            shared_data=shared_data,
+        )
+        # No exploration.
+        if not args.explore_during_inference:
+            rl_module_out = rl_module.forward_inference(input_dict)
+        # Using exploration.
+        else:
+            rl_module_out = rl_module.forward_exploration(input_dict)
+
+        to_env = module_to_env(
+            data=rl_module_out,
+            episodes=[episode],  # ConnectorV2 pipelines operate on lists of episodes.
+            rl_module=rl_module,
+            explore=args.explore_during_inference,
+            shared_data=shared_data,
+        )
+        # Send the computed action to the env. Note that the RLModule and the
+        # connector pipelines work on batched data (B=1 in this case), whereas the Env
+        # is not vectorized here, so we need to use `action[0]`.
+        action = to_env.pop(Columns.ACTIONS)[0]
+        obs, reward, terminated, truncated, _ = env.step(action)
+        episode.add_env_step(
+            obs,
+            action,
+            reward,
+            terminated=terminated,
+            truncated=truncated,
+            # Same here: [0] b/c RLModule output is batched (w/ B=1).
+            extra_model_outputs={k: v[0] for k, v in to_env.items()},
+        )
+
+        # Is the episode `done`? -> Reset.
+        if episode.is_done:
+            print(f"Episode done: Total reward = {episode.get_return()}")
+            obs, info = env.reset()
+            episode = SingleAgentEpisode(
+                observations=[obs],
+                observation_space=env.observation_space,
+                action_space=env.action_space,
+            )
+            num_episodes += 1
+
+    print(f"Done performing action inference through {num_episodes} Episodes")