Gym: First step of tutorial crashes.

[jagill]

I installed gym in a virtualenv, and ran a script that was a copy of the first step of the tutorial. After the first iteration, it quite after it raised an exception: ImportError: sys.meta_path is None, Python is likely shutting down, after the warning

WARN: You are calling 'step()' even though this environment has already returned done = True. You should always call 'reset()' once you receive 'done = True' -- any further steps are undefined behavior.

Python version is 3.7.0, gym version os 0.10.5. The exact file I ran, and all the versions, can be found in gist https://gist.github.com/jagill/5aa64abac2d9bc81ec1d16ab4fa7ee1c

This was after a reboot, so things should be relatively clean.

[jagill]

Btw, calling if done: env.reset() (as the warning suggests) mostly solves the problem. The system exits with the same ImportError after the last iteration.

[romaroma]

The same issue on Windows 10, Python 3.7.0

[christopherhesse]

Your fix is correct, you should be able to fix the pyglet error by closing the environment:

import gym
env = gym.make('CartPole-v0')

env.reset()
for _ in range(1000):
    env.render()
    obs, rew, done, info = env.step(env.action_space.sample()) # take a random action
    if done:
       env.reset()
env.close()

[decanbay]

You do not have to reset env everytime, it is just it makes it so fast and does not close it at the end of a loop, just simply add time.sleep()

import gym
import time
env = gym.make('CartPole-v0')
env.reset()
for i in range(500):
    env.render()
    env.step(env.action_space.sample()) # take a random action
    time.sleep(0.02)
    if i%10==0: print(i)
env.close()