137 lines
5.0 KiB
Python
137 lines
5.0 KiB
Python
"""Example demo'ing async gym vector envs, in which sub-envs have their own process.
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Setting up env vectorization works through setting the `config.num_envs_per_env_runner`
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value to > 1. However, by default the n sub-environments are stepped through
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sequentially, rather than in parallel.
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This script shows the effect of setting the `config.gym_env_vectorize_mode` from its
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default value of "sync" (all sub envs are located in the same EnvRunner process)
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to "async" (all sub envs in each EnvRunner get their own process).
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This example:
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- shows, which config settings to change in order to switch from sub-envs being
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stepped in sequence to each sub-envs owning its own process (and compute resource)
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and thus the vector being stepped in parallel.
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- shows, how this setup can increase EnvRunner performance significantly, especially
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for heavier, slower environments.
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- uses an artificially slow CartPole-v1 environment for demonstration purposes.
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How to run this script
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----------------------
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`python [script file name].py `
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Use the `--vectorize-mode=both` option to run both modes (sync and async)
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through Tune at the same time and get a better comparison of the throughputs
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achieved.
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For debugging, use the following additional command line options
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`--no-tune --num-env-runners=0`
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which should allow you to set breakpoints anywhere in the RLlib code and
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have the execution stop there for inspection and debugging.
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For logging to your WandB account, use:
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`--wandb-key=[your WandB API key] --wandb-project=[some project name]
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--wandb-run-name=[optional: WandB run name (within the defined project)]`
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Results to expect
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-----------------
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You should see results similar to the following in your console output
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when using the
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+--------------------------+------------+------------------------+------+
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| Trial name | status | gym_env_vectorize_mode | iter |
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| | | | |
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|--------------------------+------------+------------------------+------+
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| PPO_slow-env_6ddf4_00000 | TERMINATED | sync | 4 |
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| PPO_slow-env_6ddf4_00001 | TERMINATED | async | 4 |
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+--------------------------+------------+------------------------+------+
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+------------------+----------------------+------------------------+
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| total time (s) | episode_return_mean | num_env_steps_sample |
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| | | d_lifetime |
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|------------------+----------------------+------------------------+
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| 60.8794 | 73.53 | 16040 |
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| 19.1203 | 73.86 | 16037 |
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+------------------+----------------------+------------------------+
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You can see that the async mode, given that the env is sufficiently slow,
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achieves much better results when using vectorization.
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You should see no difference, however, when only using
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`--num-envs-per-env-runner=1`.
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"""
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import time
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import gymnasium as gym
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from ray import tune
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from ray.rllib.algorithms.ppo import PPOConfig
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from ray.rllib.examples.utils import (
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add_rllib_example_script_args,
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run_rllib_example_script_experiment,
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)
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parser = add_rllib_example_script_args(default_reward=60.0)
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parser.set_defaults(
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env="CartPole-v1",
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num_envs_per_env_runner=6,
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)
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parser.add_argument(
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"--vectorize-mode",
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type=str,
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default="async",
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help="The value `gym.envs.registration.VectorizeMode` to use for env "
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"vectorization. sync steps through all sub-envs in sequence. 'async' (default) "
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"parallelizes sub-envs through multiprocessing and can speed up EnvRunners "
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"significantly. Use the special value `both` to run both 'async' and 'sync' through a "
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"Tune grid-search.",
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)
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class SlowEnv(gym.ObservationWrapper):
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def observation(self, observation):
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time.sleep(0.005)
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return observation
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if __name__ == "__main__":
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args = parser.parse_args()
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if args.no_tune and args.vectorize_mode == "both":
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raise ValueError(
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"Can't run this script with both --no-tune and --vectorize-mode=both!"
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)
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# Wrap the env with the slowness wrapper.
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def _env_creator(cfg):
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return SlowEnv(gym.make(args.env, **cfg))
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tune.register_env("slow-env", _env_creator)
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base_config = (
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PPOConfig()
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.environment("slow-env")
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.env_runners(
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gym_env_vectorize_mode=(
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tune.grid_search(["sync", "async"])
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if args.vectorize_mode == "both"
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else args.vectorize_mode
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),
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)
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)
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results = run_rllib_example_script_experiment(base_config, args)
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# Compare the throughputs and assert that ASYNC is much faster than SYNC.
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if args.vectorize_mode == "both":
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throughput_sync = (
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results[0].metrics["num_env_steps_sampled_lifetime"]
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/ results[0].metrics["time_total_s"]
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)
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throughput_async = (
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results[1].metrics["num_env_steps_sampled_lifetime"]
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/ results[1].metrics["time_total_s"]
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)
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assert throughput_async > throughput_sync
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