本文介绍了Flask APP-ValueError:信号仅在主线程中有效的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我尝试创建一个简单的烧瓶应用程序:
I try to create a simple flask app:
from flask import Flask
app = Flask(__name__)
if __name__ == '__main__':
app.run()
但是当我添加调试时:
FLASK_APP = run.py
FLASK_ENV = development
FLASK_DEBUG = 1
我遇到以下错误:
ValueError:信号仅在主线程中起作用
这里是完整的堆栈跟踪
FLASK_APP = run.py
FLASK_ENV = development
FLASK_DEBUG = 1
In folder c:/MyProjectPath/api
c:\MyProjectPath\api\venv\Scripts\python.exe -m flask run
* Serving Flask-SocketIO app "run.py"
* Forcing debug mode on
* Restarting with stat
* Debugger is active!
* Debugger PIN: 283-122-745
Exception in thread Thread-1:
Traceback (most recent call last):
File "c:\appdata\local\programs\python\python37\Lib\threading.py", line 917, in _bootstrap_inner
self.run()
File "c:\appdata\local\programs\python\python37\Lib\threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "c:\MyProjectPath\api\venv\lib\site-packages\flask_socketio\cli.py", line 59, in run_server
return run_command()
File "c:\MyProjectPath\api\venv\lib\site-packages\click\core.py", line 764, in __call__
return self.main(*args, **kwargs)
File "c:\MyProjectPath\api\venv\lib\site-packages\click\core.py", line 717, in main
rv = self.invoke(ctx)
File "c:\MyProjectPath\api\venv\lib\site-packages\click\core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "c:\MyProjectPath\api\venv\lib\site-packages\click\core.py", line 555, in invoke
return callback(*args, **kwargs)
File "c:\MyProjectPath\api\venv\lib\site-packages\click\decorators.py", line 64, in new_func
return ctx.invoke(f, obj, *args, **kwargs)
File "c:\MyProjectPath\api\venv\lib\site-packages\click\core.py", line 555, in invoke
return callback(*args, **kwargs)
File "c:\MyProjectPath\api\venv\lib\site-packages\flask\cli.py", line 771, in run_command
threaded=with_threads, ssl_context=cert)
File "c:\MyProjectPath\api\venv\lib\site-packages\werkzeug\serving.py", line 812, in run_simple
reloader_type)
File "c:\MyProjectPath\api\venv\lib\site-packages\werkzeug\_reloader.py", line 267, in run_with_reloader
signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
File "c:\appdata\local\programs\python\python37\Lib\signal.py", line 47, in signal
handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
ValueError: signal only works in main thread
推荐答案
您面临的问题与Flask-SocketIO软件包中的错误有关,该软件包替代了flask run
命令.因此,即使您不导入Flask-SocketIO,也始终可以使用它.有几种解决方案:
The problem you are facing has to do with a bug in the Flask-SocketIO package which replaces the flask run
command. Due to this Flask-SocketIO is always used even if you don’t import it. There are several solutions:
- 卸载Flask-SocketIO
- 请勿使用
flask run
,而是运行程序的主文件 - 禁用调试
- 如果需要调试,请禁用自动加载
flask run --no-reload
- Uninstall Flask-SocketIO
- Do not use
flask run
but run the main file of your program - Disable debugging
- Disable auto loading if debugging required
flask run --no-reload
关于Flask-SocketIO错误的参考:问题817
Reference to the Flask-SocketIO bug: issue 817
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