树莓派Python3安装OpenCV后无法import

开发环境树莓派4B，使用官方标配系统，系统自带python3，

pip3 install opencv-python

速度太慢，我就把他下面的链接贴到浏览器下载了whl文件，用这个安装的，完事之后报错下面，心累

pi@raspberrypi:~ $ python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12) 
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
Traceback (most recent call last):
  File "", line 1, in 
  File "/home/pi/.local/lib/python3.7/site-packages/cv2/__init__.py", line 3, in 
    from .cv2 import *
ImportError: /home/pi/.local/lib/python3.7/site-packages/cv2/cv2.cpython-37m-arm-linux-gnueabihf.so: undefined symbol: __atomic_fetch_add_8

然后我认为的解决方法，找到报错信息中的cv2.cpython-37m-arm-linux-gnueabihf.so这个文件，改名cv2.so，用命令复制一份最好，然后

pip3 unistall opencv-python