网络|【python】Mininet+ryu错误(Import Error: cannot import name poll)

在同一python interpreter中分别执行ryuapp和mininet时没有问题,但当在ryuapp中内嵌使用Mininet时,会报如下错误:

...... File "build/bdist.linux-x86_64/egg/mininet/util.py", line 7, in ImportError: cannot import name poll

【网络|【python】Mininet+ryu错误(Import Error: cannot import name poll)】经过一番查找找到了遇到同样问题的人:
mininet - Import Error: cannot import name poll - Stack Overflow
ImportError: cannot import name poll · Issue #1 · OpenState-SDN/spider
按照github上的回答,降级eventlet库可以解决问题,但报错:
ERROR: ryu 4.31 has requirement eventlet!=0.18.3,!=0.20.1,!=0.21.0,!=0.23.0,>=0.18.2, but you'll have eventlet 0.17.4 which is incompatible.

按照提示,尝试了几个版本,最后成功解决问题:
pip install -I eventlet==0.18.4 pip install eventlet==0.18.4

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