signal only works in main thread of the main interpreter

[mudassar111]

I am getting this error "signal only works in main thread of the main interpreter". Can you please explain it to me, how can I rid of it? @BugzTheBunny

[BugzTheBunny]

Could you elaborate more? how can I recreate it? didn't see it happen.

[mudassar111]

ValueError: signal only works in main thread of the main interpreter

File "C:\Python39\lib\site-packages\streamlit\script_runner.py", line 354, in _run_script
exec(code, module.dict)
File "C:\Python39\streamlit_navbar-main\application.py", line 24, in
app.run(debug=True)
File "C:\Python39\lib\site-packages\flask\app.py", line 922, in run
run_simple(t.cast(str, host), port, self, **options)
File "C:\Python39\lib\site-packages\werkzeug\serving.py", line 1000, in run_simple
_rwr(
File "C:\Python39\lib\site-packages\werkzeug_reloader.py", line 411, in run_with_reloader
signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
File "C:\Python39\lib\signal.py", line 47, in signal
handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))

[mudassar111]

This is the error I got when I run "application.py" file @BugzTheBunny

[BugzTheBunny]

Hi @mudassar111 sorry for the late response,

You are saying that when trying to run the code as it is in this repo, this is the Error that you are getting?
If so, can you try to rerun it with a different python version? 3.8 for example? because it's really odd, I tried to rerun it, and everything works fine, even with the newest Streamlit version..

[mudassar111]

ValueError: signal only works in main thread
Traceback:

File "c:\python38\lib\site-packages\streamlit\script_runner.py", line 354, in _run_script
exec(code, module.dict)
File "C:\Python38\streamlit_navbar-main\application.py", line 24, in
app.run(debug=True)
File "c:\python38\lib\site-packages\flask\app.py", line 920, in run
run_simple(t.cast(str, host), port, self, **options)
File "c:\python38\lib\site-packages\werkzeug\serving.py", line 1002, in run_simple
_rwr(
File "c:\python38\lib\site-packages\werkzeug_reloader.py", line 411, in run_with_reloader
signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
File "c:\python38\lib\signal.py", line 47, in signal
handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))

[mudassar111]

Brother I am getting the same error @BugzTheBunny

[BugzTheBunny]

Hey @mudassar111,

It appears the problem is not related to the code, you should read this thread -
https://stackoverflow.com/questions/54749342/valueerror-signal-only-works-in-main-thread

Cheers

[chiehpower]

Encountered the same issue here.

$ streamlit run application.py                                                           

  You can now view your Streamlit app in your browser.

  Local URL: http://localhost:8501
  Network URL: http://10.1.2.84:8501

 * Serving Flask app 'application' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: on
2022-04-07 13:55:12.448  * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
2022-04-07 13:55:12.449 Traceback (most recent call last):
  File "/home/chieh/.local/lib/python3.8/site-packages/streamlit/script_runner.py", line 430, in _run_script
    exec(code, module.__dict__)
  File "/home/chieh/472GB/github/streamlit_navbar/application.py", line 13, in <module>
    app.run(debug=True)
  File "/home/chieh/.local/lib/python3.8/site-packages/flask/app.py", line 920, in run
    run_simple(t.cast(str, host), port, self, **options)
  File "/home/chieh/.local/lib/python3.8/site-packages/werkzeug/serving.py", line 1002, in run_simple
    _rwr(
  File "/home/chieh/.local/lib/python3.8/site-packages/werkzeug/_reloader.py", line 411, in run_with_reloader
    signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
  File "/usr/lib/python3.8/signal.py", line 47, in signal
    handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
ValueError: signal only works in main thread

[thestonedape]

hey any updates on fixing this error.

[EPanni]

Hello @thestonedape , (Trying to help)

That is not in the same context but I hope it can give you some insights. 👍

I came across a similar issue in my application when using (flask_socketio) and it was solved by disabling the debug mode.

Reason: When you run in Debug, the reloader expects to run in the main thread.

web_socket = Thread(target=socketio.run, args=(app,), kwargs={'host':'0.0.0.0', 'port': , 'debug':False, use_reloader':False})

[yohanespm77]

Hello @BugzTheBunny , why folium cannot be displayed in streamlit_navbar ?

The output :