Error: There is no current event loop in thread 'MainThread'

[AlekseyPython]

Python 3.7.2

In my processing, the main function is wrapped by error interceptors and the interception is performed correctly:

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try:     downloader = Downloader.Downloader()     downloader.download() except Exception as err:     General.exist_error = True     Events.Sender.send_error(err)

But if an error occurred (and was correctly intercepted!), then the following start of processing fall down on the line:

1	self.event_exist_data = Event()

with error:

Error:
There is no current event loop in thread 'MainThread'

I found the place of the code in which the error occurs (module events):

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class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy): ...     def get_event_loop(self):         """Get the event loop.           This may be None or an instance of EventLoop.         """         if (self._local._loop is None and #TRUE                 not self._local._set_called and #FALSE BECAUSE self._local._set_called IS TRUE !!!                 isinstance(threading.current_thread(), threading._MainThread)): #TRUE             self.set_event_loop(self.new_event_loop())           if self._local._loop is None:             raise RuntimeError('There is no current event loop in thread %r.' #On the second, third ... iteration I get here!!!                                % threading.current_thread().name)           return self._local._loop

[nilamo]

I think you'll need to show more code. Especially where/how you're using event loops. Without seeing that, we can't really guess why there's a problem with the event loop.

[AlekseyPython]

Thank you for your interest!
There is no low-level work with the event loop anywhere, just the use of the run() method in a single place (presented below). In my code specific classes are wrapped by decorators who register them for execution in the REGISTRY list (it is currently only 1 class):

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class AbstaractUnit:     def __init__(self):         self.fill_coroutines()               @abstractmethod        def fill_coroutines(self): pass           async def _create_workers(self) -> None:         await asyncio.gather(*self.coroutines)               def __call__(self) -> None:         asyncio.run(self._create_workers())   class Downloader(_Unit.AbstaractUnit):     REGISTRY = []           @classmethod     def register(cls):         def decorator(child_class):             cls.REGISTRY.append(child_class)             return child_class                   return decorator           def __init__(self):         _Unit.AbstaractUnit.__init__(self)               def fill_coroutines(self):         self.coroutines = []         for Method in self.REGISTRY:             coroutine = Method()()             self.coroutines.append(coroutine)                   def download(self):         self.__call__()

[AlekseyPython]

In this way, I run the code for execution and intercept errors:

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try:             downloader = Downloader.Downloader()                            downloader.download()         except Exception as err:             General.exist_error = True             Events.Sender.send_error(err)

[nilamo]

Is there any way you can put together a complete example I can run, that demonstrates the issue?
The only thing I can see, is that the manager/AbstractUnit is calling asyncio.run(), which might not be safe to call more than once.

I get that from the docs: https://docs.python.org/3/library/asynci...syncio.run

This function cannot be called when another asyncio event loop is running in the same thread.

...

This function always creates a new event loop and closes it at the end. It should be used as a main entry point for asyncio programs, and should ideally only be called once.

[AlekseyPython]

I get that from the docs: https://docs.python.org/3/library/asynci...syncio.run

This function cannot be called when another asyncio event loop is running in the same thread.

Thank you!
I replaced:

1	asyncio.run(self._create_workers())

on this lines:

1 2	ioloop = asyncio.get_event_loop() ioloop.run_until_complete(self._create_workers())

and the error, that occurred when the processing was restarted, disappeared.