Adding optional SIGINT handler. It raises RuntimeError when run on a …

[quancore]

Adding an optional SIGINT handler. Default SIGINT handler addition is problematical on a thread other then main thread since add_signal_handler only work in the main thread.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
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No Coverage information
0.0% Duplication

[afunTW]

Reference to the add_signal_handler issue https://bugs.python.org/issue34679

[afunTW]

According to the comment in the Python issue thread, it seems only happened in python 3.8.

The issue is related to Python 3.8 and master only. 3.6-3.7 are not affected - Andrew Svetlov

@bluet Is this project going to support python 3.8 in the future?
@quancore could you please provide more information including the environment? how do we reproduce the error?

[quancore]

My env was Ubuntu, python 3.7. So the problem also persist for python 3.7. To reproduce runs the proxy broker on a thread.
Also please check: constverum#109

[bluet]

@afunTW 你幫我決定一下 XD
如果覺得 ok ，這個 merge 並不會產生危害（且能解決使用者的問題）的話，可以直接 merge

[afunTW]

@bluet Since the same issue and PR happened in source repo constverum#109
It's better to handle this issue so far although we still not able to interrupt in non-main thread.

LGTM