CentOS6.5部署OpenAI Gym环境时Box2D-kengz安装报错求助

我之前在CentOS 6.5上部署OpenAI Gym时，碰到了和你一模一样的问题——就在执行pip install '.[all]'时卡在了Box2D-kengz的编译环节。下面我把完整的安装流程、遇到的错误以及解决办法整理出来：

初始安装步骤 #

我一开始是按照以下流程操作的：

• 安装Anaconda：先下载安装包再执行安装脚本

  wget --no-check-certificate https://repo.anaconda.com/archive/Anaconda3-5.1.0-Linux-x86_64.sh
  bash Anaconda3-5.1.0-Linux-x86_64.sh
  

• 创建虚拟环境：

  conda create --name gymlab python=3.6
  

• 安装Gym：
  1. 激活虚拟环境：

     source activate gymlab
     

  2. 克隆Gym仓库：

     git clone https://github.com/openai/gym.git
     

  3. 进入仓库目录：

     cd gym
     

  4. 尝试安装全量依赖：

     pip install '.[all]'
     

遇到的编译错误 #

执行最后一步时，出现了Box2D-kengz的编译失败，完整错误输出如下：

Processing /root/gym
Requirement already satisfied: numpy>=1.10.4 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (1.14.3)
Requirement already satisfied: requests>=2.0 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (2.18.4)
Requirement already satisfied: six in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (1.11.0)
Requirement already satisfied: pyglet>=1.2.0 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (1.3.2)
Requirement already satisfied: atari_py>=0.1.1 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (0.1.1)
Requirement already satisfied: Pillow in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (5.1.0)
Requirement already satisfied: PyOpenGL in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from gym==0.10.5) (3.1.0)
Collecting Box2D-kengz (from gym==0.10.5)
Using cached https://files.pythonhosted.org/packages/81/20/51d6c0c87f7642efb709c518fb0ca8e5eab068259588552c41da5926ae27/Box2D-kengz-2.3.3.tar.gz
Collecting mujoco_py>=1.50 (from gym==0.10.5)
Collecting imageio (from gym==0.10.5)
Using cached https://files.pythonhosted.org/packages/a7/1d/33c8686072148b3b0fcc12a2e0857dd8316b8ae20a0fa66c8d6a6d01c05c/imageio-2.3.0-py2.py3-none-any.whl
Requirement already satisfied: chardet<3.1.0,>=3.0.2 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from requests>=2.0->gym==0.10.5) (3.0.4)
Requirement already satisfied: certifi>=2017.4.17 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from requests>=2.0->gym==0.10.5) (2018.4.16)
Requirement already satisfied: idna<2.7,>=2.5 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from requests>=2.0->gym==0.10.5) (2.6)
Requirement already satisfied: urllib3<1.23,>=1.21.1 in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from requests>=2.0->gym==0.10.5) (1.22)
Requirement already satisfied: future in /root/anaconda3/envs/gymlab/lib/python3.6/site-packages (from pyglet>=1.2.0->gym==0.10.5) (0.16.0)
Collecting glfw>=1.4.0 (from mujoco_py>=1.50->gym==0.10.5)
Collecting cffi>=1.10 (from mujoco_py>=1.50->gym==0.10.5)
Using cached https://files.pythonhosted.org/packages/6d/c0/47db8f624f3e4e2f3f27be03a93379d1ba16a1450a7b1aacfa0366e2c0dd/cffi-1.11.5-cp36-cp36m-manylinux1_x86_64.whl
Collecting Cython>=0.27.2 (from mujoco_py>=1.50->gym==0.10.5)
Using cached https://files.pythonhosted.org/packages/19/eb/c4d9f3beafd5ac0615936860bcee41d93ca58f8734a16715da0037d2c468/Cython-0.28.2-cp36-cp36m-manylinux1_x86_64.whl
Collecting pycparser (from cffi>=1.10->mujoco_py>=1.50->gym==0.10.5)
Building wheels for collected packages: gym, Box2D-kengz
Running setup.py bdist_wheel for gym ... done
Stored in directory: /tmp/pip-ephem-wheel-cache-or4iim1z/wheels/6e/18/10/1234738b0aafab3f8f70d61d2763dc3efda78a41d153584dee
Running setup.py bdist_wheel for Box2D-kengz ... error
Complete output from command /root/anaconda3/envs/gymlab/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-5jh8n6q7/Box2D-kengz/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /tmp/pip-wheel-ckydr3cn --python-tag cp36:
Using setuptools (version 39.1.0).
running bdist_wheel
running build
running build_py
creating build
creating build/lib.linux-x86_64-3.6
creating build/lib.linux-x86_64-3.6/Box2D

问题分析 #

这个问题的核心原因是CentOS 6.5自带的GCC版本太低（默认是4.4.7），而Box2D-kengz的编译需要用到C++11特性，老版本的GCC不支持这些特性，导致编译失败。另外，系统可能还缺少一些必要的图形和编译依赖库。

解决步骤 #

1. 升级GCC版本到支持C++11的版本 #

CentOS 6.5可以通过SCL（Software Collections）安装更高版本的GCC：

# 安装SCL源
yum install -y centos-release-scl
# 安装GCC 4.8（支持C++11）
yum install -y devtoolset-3-gcc devtoolset-3-gcc-c++
# 激活新版本GCC（临时生效，重启终端后需要重新激活）
scl enable devtoolset-3 bash
# 如果需要永久生效，把下面的命令添加到~/.bashrc末尾
echo "source /opt/rh/devtoolset-3/enable" >> ~/.bashrc

2. 安装系统依赖库 #

安装编译Box2D和Gym所需的系统依赖：

yum install -y cmake libX11-devel mesa-libGL-devel

3. 替换Box2D-kengz为官方维护的包 #

Box2D-kengz是第三方修改版，容易出现兼容性问题，建议改用官方维护的box2d-py：

# 先卸载残留的Box2D-kengz
pip uninstall -y Box2D-kengz
# 安装官方Box2D包
pip install box2d-py

4. 重新安装Gym #

回到Gym目录，重新执行安装命令：

cd gym
# 如果不需要Mujoco（需要付费许可证），可以只安装基础和常用环境
pip install '.[classic_control,box2d]'
# 如果确实需要全量安装（注意Mujoco需要单独配置许可证）
pip install '.[all]'

额外提示 #

如果不需要Mujoco相关的环境，建议只安装必要的部分，避免不必要的麻烦。另外，CentOS 6.5已经停止维护，后续可能会遇到更多依赖兼容性问题，如果条件允许，建议升级到CentOS 7或更高版本。

内容的提问来源于stack exchange，提问作者Jackon