Tutorial code cannot work on my ubuntu which already has an ovs

[Yan Kai]

- [ ] This is a doc addition request.
Everything worked fine if I follow the tutorial and use the backend in a virtual environment. But issues occur if I use the ovs installed using "apt-get install openvswitch-switch" (Ubuntu 20.04). When I try to run the tutorial python code with this ovs as the backend, it always stucks at line "conn = connection.Connection(idl=idl, timeout=60)". And eventually a time out. The valueof src-dir and run-dir are configured correctly. Running code as root also solves nothing. I'm wondering what should I do to let ovsdbapp work fine with this installed ovs.

The error log of timeout is provided below
-----------------------------------
Release: 2.5.0.dev3 on 2023-07-18 15:07:55
SHA: dae455b6eea3dcae931d07d4a81c03190e8259ed
Source: https://opendev.org/openstack/ovsdbapp/src/doc/source/user/tutorial.rst
URL: https://docs.openstack.org/ovsdbapp/latest/user/tutorial.html