# Goals of the PR The PR introduces **no changes to functionality**, apart from improved input validation here and there. The main goals are to reduce some complexity of the code, to improve types and IDE completions, and to extend documentation and block comments where appropriate. Because of the change to the trainer interfaces, many files are affected (more details below), but still the overall changes are "small" in a certain sense. ## Major Change 1 - BatchProtocol **TL;DR:** One can now annotate which fields the batch is expected to have on input params and which fields a returned batch has. Should be useful for reading the code. getting meaningful IDE support, and catching bugs with mypy. This annotation strategy will continue to work if Batch is replaced by TensorDict or by something else. **In more detail:** Batch itself has no fields and using it for annotations is of limited informational power. Batches with fields are not separate classes but instead instances of Batch directly, so there is no type that could be used for annotation. Fortunately, python `Protocol` is here for the rescue. With these changes we can now do things like ```python class ActionBatchProtocol(BatchProtocol): logits: Sequence[Union[tuple, torch.Tensor]] dist: torch.distributions.Distribution act: torch.Tensor state: Optional[torch.Tensor] class RolloutBatchProtocol(BatchProtocol): obs: torch.Tensor obs_next: torch.Tensor info: Dict[str, Any] rew: torch.Tensor terminated: torch.Tensor truncated: torch.Tensor class PGPolicy(BasePolicy): ... def forward( self, batch: RolloutBatchProtocol, state: Optional[Union[dict, Batch, np.ndarray]] = None, **kwargs: Any, ) -> ActionBatchProtocol: ``` The IDE and mypy are now very helpful in finding errors and in auto-completion, whereas before the tools couldn't assist in that at all. ## Major Change 2 - remove duplication in trainer package **TL;DR:** There was a lot of duplication between `BaseTrainer` and its subclasses. Even worse, it was almost-duplication. There was also interface fragmentation through things like `onpolicy_trainer`. Now this duplication is gone and all downstream code was adjusted. **In more detail:** Since this change affects a lot of code, I would like to explain why I thought it to be necessary. 1. The subclasses of `BaseTrainer` just duplicated docstrings and constructors. What's worse, they changed the order of args there, even turning some kwargs of BaseTrainer into args. They also had the arg `learning_type` which was passed as kwarg to the base class and was unused there. This made things difficult to maintain, and in fact some errors were already present in the duplicated docstrings. 2. The "functions" a la `onpolicy_trainer`, which just called the `OnpolicyTrainer.run`, not only introduced interface fragmentation but also completely obfuscated the docstring and interfaces. They themselves had no dosctring and the interface was just `*args, **kwargs`, which makes it impossible to understand what they do and which things can be passed without reading their implementation, then reading the docstring of the associated class, etc. Needless to say, mypy and IDEs provide no support with such functions. Nevertheless, they were used everywhere in the code-base. I didn't find the sacrifices in clarity and complexity justified just for the sake of not having to write `.run()` after instantiating a trainer. 3. The trainers are all very similar to each other. As for my application I needed a new trainer, I wanted to understand their structure. The similarity, however, was hard to discover since they were all in separate modules and there was so much duplication. I kept staring at the constructors for a while until I figured out that essentially no changes to the superclass were introduced. Now they are all in the same module and the similarities/differences between them are much easier to grasp (in my opinion) 4. Because of (1), I had to manually change and check a lot of code, which was very tedious and boring. This kind of work won't be necessary in the future, since now IDEs can be used for changing signatures, renaming args and kwargs, changing class names and so on. I have some more reasons, but maybe the above ones are convincing enough. ## Minor changes: improved input validation and types I added input validation for things like `state` and `action_scaling` (which only makes sense for continuous envs). After adding this, some tests failed to pass this validation. There I added `action_scaling=isinstance(env.action_space, Box)`, after which tests were green. I don't know why the tests were green before, since action scaling doesn't make sense for discrete actions. I guess some aspect was not tested and didn't crash. I also added Literal in some places, in particular for `action_bound_method`. Now it is no longer allowed to pass an empty string, instead one should pass `None`. Also here there is input validation with clear error messages. @Trinkle23897 The functional tests are green. I didn't want to fix the formatting, since it will change in the next PR that will solve #914 anyway. I also found a whole bunch of code in `docs/_static`, which I just deleted (shouldn't it be copied from the sources during docs build instead of committed?). I also haven't adjusted the documentation yet, which atm still mentions the trainers of the type `onpolicy_trainer(...)` instead of `OnpolicyTrainer(...).run()` ## Breaking Changes The adjustments to the trainer package introduce breaking changes as duplicated interfaces are deleted. However, it should be very easy for users to adjust to them --------- Co-authored-by: Michael Panchenko <m.panchenko@appliedai.de>
Atari Environment
EnvPool
We highly recommend using envpool to run the following experiments. To install, in a linux machine, type:
pip install envpool
After that, atari_wrapper
will automatically switch to envpool's Atari env. EnvPool's implementation is much faster (about 2~3x faster for pure execution speed, 1.5x for overall RL training pipeline) than python vectorized env implementation, and it's behavior is consistent to that approach (OpenAI wrapper), which will describe below.
For more information, please refer to EnvPool's GitHub, Docs, and 3rd-party report.
ALE-py
The sample speed is ~3000 env step per second (~12000 Atari frame per second in fact since we use frame_stack=4) under the normal mode (use a CNN policy and a collector, also storing data into the buffer).
The env wrapper is a crucial thing. Without wrappers, the agent cannot perform well enough on Atari games. Many existing RL codebases use OpenAI wrapper, but it is not the original DeepMind version (related issue). Dopamine has a different wrapper but unfortunately it cannot work very well in our codebase.
DQN (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
Note: The eps_train_final
and eps_test
in the original DQN paper is 0.1 and 0.01, but some works found that smaller eps helps improve the performance. Also, a large batchsize (say 64 instead of 32) will help faster convergence but will slow down the training speed.
We haven't tuned this result to the best, so have fun with playing these hyperparameters!
C51 (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
Note: The selection of n_step
is based on Figure 6 in the Rainbow paper.
QRDQN (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
IQN (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
FQF (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
Rainbow (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
PPO (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.
SAC (single run)
One epoch here is equal to 100,000 env step, 100 epochs stand for 10M.