## What do these changes do?
**Vectorized envs**: Users can either implement `VectorEnv`, or alternatively set `num_envs=N` to auto-vectorize gym envs (this vectorizes just the action computation part).
```
# CartPole-v0 on single core with 64x64 MLP:
# vector_width=1:
Actions per second 2720.1284458322966
# vector_width=8:
Actions per second 13773.035334888269
# vector_width=64:
Actions per second 37903.20472563333
```
**Async envs**: The more general form of `VectorEnv` is `AsyncVectorEnv`, which allows agents to execute out of lockstep. We use this as an adapter to support `ServingEnv`. Since we can convert any other form of env to `AsyncVectorEnv`, utils.sampler has been rewritten to run against this interface.
**Policy serving**: This provides an env which is not stepped. Rather, the env executes in its own thread, querying the policy for actions via `self.get_action(obs)`, and reporting results via `self.log_returns(rewards)`. We also support logging of off-policy actions via `self.log_action(obs, action)`. This is a more convenient API for some use cases, and also provides parallelizable support for policy serving (for example, if you start a HTTP server in the env) and ingest of offline logs (if the env reads from serving logs).
Any of these types of envs can be passed to RLlib agents. RLlib handles conversions internally in CommonPolicyEvaluator, for example:
```
gym.Env => rllib.VectorEnv => rllib.AsyncVectorEnv
rllib.ServingEnv => rllib.AsyncVectorEnv
```
* Add flake8 to Travis
* Add flake8-comprehensions
[flake8 plugin](https://github.com/adamchainz/flake8-comprehensions) that
checks for useless constructions.
* Use generators instead of lists where appropriate
A lot of the builtins can take in generators instead of lists.
This commit applies `flake8-comprehensions` to find them.
* Fix lint error
* Fix some string formatting
The rest can be fixed in another PR
* Fix compound literals syntax
This should probably be merged after #1963.
* dict() -> {}
* Use dict literal syntax
dict(...) -> {...}
* Rewrite nested dicts
* Fix hanging indent
* Add missing import
* Add missing quote
* fmt
* Add missing whitespace
* rm duplicate pip install
This is already installed in another file.
* Fix indent
* move `merge_dicts` into utils
* Bring up to date with `master`
* Add automatic syntax upgrade
* rm pyupgrade
In case users want to still use it on their own, the upgrade-syn.sh script was
left in the `.travis` dir.
* Make ActorHandles pickleable, also make proper ActorHandle and ActorClass classes.
* Fix bug.
* Fix actor test bug.
* Update __ray_terminate__ usage.
* Fix most linting, add documentation, and small cleanups.
* Handle forking and pickling differently for actor handles. Fix linting.
* Fixes for named actors via pickling.
* Generate actor handle IDs deterministically in the pickling case.
