ValueError: signal only works in main thread

[bin]

Describe the bug
When running on arch linux with /opt/botamusique/venv/bin/python /opt/botamusique/mumbleBot.py --config /opt/botamusique/configuration.ini, python version 3.8, 3.7, or 3.6, I get the following error: Exception in thread WebThread: Traceback (most recent call last): File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner self.run() File "/usr/lib/python3.6/threading.py", line 864, in run self._target(*self._args, **self._kwargs) File "/opt/botamusique/mumbleBot.py", line 586, in start_web_interface interface.web.run(port=port, host=addr) File "/opt/botamusique/venv/lib/python3.6/site-packages/flask/app.py", line 990, in run run_simple(host, port, self, **options) File "/opt/botamusique/venv/lib/python3.6/site-packages/werkzeug/serving.py", line 1050, in run_simple run_with_reloader(inner, extra_files, reloader_interval, reloader_type) File "/opt/botamusique/venv/lib/python3.6/site-packages/werkzeug/_reloader.py", line 330, in run_with_reloader signal.signal(signal.SIGTERM, lambda *args: sys.exit(0)) File "/usr/lib/python3.6/signal.py", line 47, in signal handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler)) ValueError: signal only works in main thread

Affected version
Tested on latest release and commit ID d24f109.

To Reproduce
Run the above command described on arch with python 3.6, 3.7, or 3.8.

Expected behavior
The web interface starts.

Happy to provide any additional info as needed.

[TerryGeng]

This is actually a bug for Flask.

But also we are not free from being blamed for our unconventional use of Flask itself :( .

I have encountered this only once, that is when I tried to set to DEBUG flag. Then it works fine for my Macbook and my Arch server. So I don't know what happened on your server.

Now I disabled other unnecessary flags. Maybe it will solve your problem.

[bin]

Yeah my googling mentioned a flask bug as well. Testing on the new commit yields the same error: ```

• Serving Flask app "interface" (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 Exception in thread WebThread: Traceback (most recent call last): File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner self.run() File "/usr/lib/python3.6/threading.py", line 864, in run self._target(*self._args, **self._kwargs) File "/opt/botamusique/mumbleBot.py", line 592, in start_web_interface interface.web.run(port=port, host=addr) File "/opt/botamusique/venv/lib/python3.6/site-packages/flask/app.py", line 990, in run run_simple(host, port, self, **options) File "/opt/botamusique/venv/lib/python3.6/site-packages/werkzeug/serving.py", line 1050, in run_simple run_with_reloader(inner, extra_files, reloader_interval, reloader_type) File "/opt/botamusique/venv/lib/python3.6/site-packages/werkzeug/_reloader.py", line 330, in run_with_reloader signal.signal(signal.SIGTERM, lambda *args: sys.exit(0)) File "/usr/lib/python3.6/signal.py", line 47, in signal handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler)) ValueError: signal only works in main thread```

[bin]

I set it to debug mode because the web app wasn't responding, so while I don't get that message if I set it to production, I can't figure out why I can't load the web interface. I can see the port bound with netstat, but attempting to access the interface yields a timeout (either from the server via localhost:8181 or from another machine).

[TerryGeng]

According to https://www.semicolonworld.com/question/58571/start-a-flask-application-in-separate-thread ,
I think it's necessary that you don't start Flask in debug mode.

As for the timeout problem, I suggest you have a look at the log file of web interface.

[TerryGeng]

If you didn't set any log file, the log will be printed out in stderr. It should looks like

[Mar 22 22:02:20 INFO MainThread] bot: botamusique version 6.0, starting...
[Mar 22 22:02:20 DEBUG MainThread] Starting in DEBUG loglevel
[Mar 22 22:02:20 INFO MainThread] Starting web interface on 127.0.0.1:8181
[Mar 22 22:02:20 DEBUG UpdateThread] update: checking for updates...
 * Serving Flask app "interface" (lazy loading)
 * Environment: development
 * Debug mode: off
 * Running on http://127.0.0.1:8181/ (Press CTRL+C to quit)
[Mar 22 22:02:20 DEBUG MainThread] bot: command added: joinme
[Mar 22 22:02:20 DEBUG MainThread] bot: command added: userban
.....
[Mar 22 22:02:20 INFO MainThread] library: rebuild directory cache
[Mar 22 22:02:20 INFO MainThread] bot: load playlist from previous session
[Mar 22 22:02:20 DEBUG Validating] playlist: start validating...
[Mar 22 22:02:20 DEBUG Validating] playlist: validating [file] Sting - Shape of My Heart (uploads/Shape of My Heart-Sting.mp3)
[Mar 22 22:02:20 DEBUG Validating] playlist: validating [file] 井草聖二 - Mellow Sunset (uploads/15.Mellow Sunset-井草聖二.mp3)
[Mar 22 22:02:20 DEBUG Validating] playlist: validating [file] 麗美 - Secret Feelings ～from childhood (uploads/05.Secret Feelings ～from childhood-麗美.mp3)
.....
[Mar 22 22:02:20 DEBUG MainThread] bot: execute ffmpeg command: ffmpeg -v warning -nostdin -i /Users/terrygeng/Desktop/source/python/botamusique/music_folder/uploads/05.Secret Feelings ～from childhood-麗美.mp3 -ac 1 -f s16le -ar 48000 -
[Mar 22 22:02:20 DEBUG MainThread] bot: Async download next asked
[Mar 22 22:02:22 DEBUG UpdateThread] update: no new version found.
127.0.0.1 - - [22/Mar/2020 22:02:27] "GET / HTTP/1.1" 200 -
[Mar 22 22:02:27 DEBUG Thread-3] web: Post request from 127.0.0.1: ImmutableMultiDict([('type', ''), ('dir', ''), ('tags', ''), ('keywords', ''), ('page', '1'), ('action', 'query')])
127.0.0.1 - - [22/Mar/2020 22:02:27] "POST /library HTTP/1.1" 404 -
127.0.0.1 - - [22/Mar/2020 22:02:27] "GET /playlist HTTP/1.1" 200 -
127.0.0.1 - - [22/Mar/2020 22:02:30] "POST /post HTTP/1.1" 200 -
127.0.0.1 - - [22/Mar/2020 22:02:30] "GET /playlist HTTP/1.1" 200 -
[Mar 22 22:02:32 DEBUG Thread-7] web: Post request from 127.0.0.1: ImmutableMultiDict([('type', 'file'), ('dir', ''), ('tags', ''), ('keywords', ''), ('page', '1'), ('action', 'query')])

Lines like

127.0.0.1 - - [22/Mar/2020 22:02:27] "GET / HTTP/1.1" 200 -

indicates your requests has been successfully processed.

If you are still facing this problem, please start the bot with argument -v and paste your logs here.

[bin]

I'm not getting that logging. Any idea why that might be? I do get [Mar 23 00:30:24 INFO MainThread] library: rebuild directory cache. Will that indexing block the rest of the bot, e.g. the web interface?

[TerryGeng]

Ehhhh.... How many files do you have in your music folder?

[bin]

4722

[TerryGeng]

Okay, I guess you need to give the bot some time to index all files. The web interface thread will wait until indexing is done.
I use the bot with approximately 500 files and it works fine.

The speed of indexing also depends on how fast your server is. If you want to see the progress of indexing, you can add this line

print(file)

after line 111 of media/cache.py.

[bin]

Thanks. I figure it may be pretty slow; it's a bit of a potato and running over a network.

[TerryGeng]

You may want to avoid rebuilding the file index every time you start the bot by setting

[bot]
refresh_cache_on_startup = False

But every time you upload files through the web interface, it will refresh the cache. And in some cases you may also need to refresh the cache manually by command !rescan or the 'Rescan' button on the web interface.

[bin]

Good to know. Thanks for your help.