mujoco.FatalError in Ubuntu 18.04.5

when i run memory_maze i met a Error below:
`/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/glfw/__init__.py:912: GLFWError: (65544) b'X11: The DISPLAY environment variable is missing'
warnings.warn(message, GLFWError)
/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/glfw/__init__.py:912: GLFWError: (65537) b'The GLFW library is not initialized'
warnings.warn(message, GLFWError)
Traceback (most recent call last):
File "/home/DQC/demo/test.py", line 4, in
env = gym.make('dmc_memory_maze:MemoryMaze-9x9-v0')
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/gym/envs/registration.py", line 640, in make
env = env_creator(**_kwargs)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dmc_memory_maze-0.2.0-py3.7.egg/dmc_memory_maze/__init__.py", line 17, in _make_gym_env
dmenv = dm_task(**kwargs)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dmc_memory_maze-0.2.0-py3.7.egg/dmc_memory_maze/tasks.py", line 25, in memory_maze_9x9
return _memory_maze(9, 3, 250, **kwargs)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dmc_memory_maze-0.2.0-py3.7.egg/dmc_memory_maze/tasks.py", line 105, in _memory_maze
strip_singleton_obs_buffer_dim=True)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/composer/environment.py", line 331, in __init__
delayed_observation_padding=delayed_observation_padding)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/composer/environment.py", line 221, in __init__
self._recompile_physics_and_update_observables()
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/composer/environment.py", line 243, in _recompile_physics_and_update_observables
self._observation_updater.reset(self._physics_proxy, self._random_state)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/composer/observation/updater.py", line 165, in reset
enabled.observation_callable())
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/composer/observation/observable/mjcf.py", line 273, in get_observation
render_flag_overrides=self._render_flag_overrides)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/mujoco/engine.py", line 220, in render
scene_callback=scene_callback)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/mujoco/engine.py", line 694, in __init__
if self._physics.contexts.mujoco is not None:
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/mujoco/engine.py", line 525, in contexts
self._make_rendering_contexts()
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/mujoco/engine.py", line 511, in _make_rendering_contexts
mujoco_context = wrapper.MjrContext(self.model, render_context)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/mujoco/wrapper/core.py", line 606, in __init__
ptr = ctx.call(mujoco.MjrContext, model.ptr, font_scale)
File "/home/DQC/anaconda3/envs/test/lib/python3.7/site-packages/dm_control/_render/executor/render_executor.py", line 136, in call
return func(*args, **kwargs)
mujoco.FatalError: an OpenGL platform library has not been loaded into this process, this most likely means that a valid OpenGL context has not been created before mjr_makeContext was called`

Bắt đầu bằng cách tái hiện việc tạo môi trường memory_maze từ dmc_memory_maze/tasks.py và ghi lại thiết lập Ubuntu, DISPLAY, GLFW và MuJoCo. Truy vết quá trình tạo ngữ cảnh kết xuất qua dm_control/mujoco/engine.py và dm_control/_render/executor/render_executor.py. Hoàn thành khi đã hiểu lỗi khởi tạo OpenGL được báo cáo và việc tạo môi trường hoặc kết xuất thành công trong một thiết lập được ghi lại.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.