I'm investigating the implementation of some algorithms of the [stable-baselines3 library](https://stable-baselines3.readthedocs.io/en/master/guide/quickstart.html).   
Specifically, I see that the documentation of some algorithms ([A2C](https://stable-baselines3.readthedocs.io/en/master/modules/a2c.html), [PPO](https://stable-baselines3.readthedocs.io/en/master/modules/ppo.html)) mentions that the implementation uses **multiple workers**. 

For the other algorithms, it doesn't say anything about it, so my question is: 

Can I assume the other algorithms use only one learner?

  
To give more context over my doubts, in the [summary table](https://stable-baselines3.readthedocs.io/en/master/guide/algos.html) of all the algorithms it's shown that each of them supports "**multi processing**". But, if I understood correctly, that only refers to using [vectorized environments](https://stable-baselines3.readthedocs.io/en/master/guide/vec_envs.html), although I wouldn't bet on it.

Final note: I tried answering answering my question looking at the code of [A2C](https://stable-baselines3.readthedocs.io/en/master/_modules/stable_baselines3/a2c/a2c.html#A2C) (which mentions using workers) and [SAC](https://stable-baselines3.readthedocs.io/en/master/_modules/stable_baselines3/sac/sac.html#SAC) (which doesn't mention workers) but that didn't help, so here I am

Stable-baselines-3 workers