Question -num-envs=<n> help - what are Unity instances

Concurrent instances are actually different copies of a Unity game (that has been built) and you can think of it as multiple editor windows. Note that because there are multiple copies of the same game running the game will need to be built[1] and this can't be used in-editor. This is different from duplicating a single arena/environment inside unity (like is done in many of the example environments).

num-envs is generally safe, but start with small numbers (so you don't eat all your computer's resources). I would suggest starting with 3 and seeing if you get a speedup. You will likely get faster training but your trained model may train differently.

[1] See https://github.com/Unity-Technologi...Executable.md#using-an-environment-executable

 

Adding to the above reply, it's safe to use in general. But you might want to adjust your config mentioned in the doc since the trainer is collecting observations from all instances at the same time and it may behave differently.

 

The training behavior could be different despite how many agents there are. There's difference because you are collecting observations from n instances instead of one and the buffer is filled up quicker with some slightly different data.
In general, this doesn't either significantly hurt or help the overall performance if you adjust the config (especially buffer size) properly, but you can get a big boost in training time.

 

Do you mean that you have multiple duplicated agents in your scene, and you're asking if it's safe to run multiple Unity instances of that scene?

 

For example like Rollerball or many other example environments that have duplicated agents, you can still use --num-envs with them to speed up training and the explanation in my previous reply still apply. The training behavior could be different since you're collecting observations from num-envs * m agents instead of m agents.