TypeError: can't pickle dolfin.cpp.geometry.Point objects

[jiangzhangze]

Important Note: We do not do technical support, nor consulting and don't answer personal questions per email.

If you have any questions, feel free to create an issue with the tag [question].
If you wish to suggest an enhancement or feature request, add the tag [feature request].
If you are submitting a bug report, please fill in the following details.

If your issue is related to a custom gym environment, please check it first using:

from stable_baselines.common.env_checker import check_env

env = CustomEnv(arg1, ...)
# It will check your custom environment and output additional warnings if needed
check_env(env)

Describe the bug
A clear and concise description of what the bug is.
TypeError: can't pickle dolfin.cpp.geometry.Point objects
when I try to use Multithreaded computation
Code example
Please try to provide a minimal example to reproduce the bug. Error messages and stack traces are also helpful.
'''
n_cpu = 12
env = SubprocVecEnv([lambda: env_ for i in range(n_cpu)])
'''
Please use the markdown code blocks
for both code and stack traces.

from stable_baselines import ...

Traceback (most recent call last): File ...

System Info
Describe the characteristic of your environment:

• Describe how the library was installed (pip, docker, source, ...)
• pip install stable-baselines
• GPU models and configuration
• Python version
• python 3.7.0
• Tensorflow version
• 1.14.0
• Versions of any other relevant libraries
  gym 0.25.2
  Additional context
  Add any other context about the problem here.