Runtime error this event loop is already running - Исправление ошибок и поиск оптимальных решений проблем

The runtimeerror this event loop is already running mistake affects your programming experience because you run the event loop while it is processing. Unfortunately, queueing async functions and waiting for synchronous results do not work, especially with event loops and other standard elements.

We wrote this in-depth debugging guide to help you remove the runtimeerror: this event loop is already running notebook bug without causing further complications.

In addition, we will exemplify why the event loop is already running pyqt5 using real-life examples and invalid instances blocking your project or application.

Why the Runtime Error Event Loop Is Already Running Error Happens?

The runtimeerror: this event loop is already running Jupyter notebook error happens because you try to initiate an already running event loop. In addition, you will likely encounter this code exception when queueing async functions and waiting for synchronous results, something the system cannot render.

For instance, the runtimeerror: this event loop is already running TikTok API bug is almost inevitable when running the incorrect loop. In addition, the exact error persists and blocks your application, although most elements and inputs are fully functional, confirming its dynamic nature.

As a result, knowing how to troubleshoot the runtimeerror: this event loop is already running FastAPI mistake, and locating the failed values is critical.

The following example helps you learn more about the incorrect exception:

Traceback (most recent call last):

File “C:UsersAdamAppDataLocalTemp/ipykernel_7764/1465954928.py”, line 1, in <module>

runfile(‘C:/Users/Adam/Documents/Python Scripts/test_bleak.py’, wdir=’C:/Users/Adam/Documents/Python Scripts’)

File “C:UsersAdamAnaconda3libsite-packagesdebugpy_vendoredpydevd_pydev_bundlepydev_umd.py”, line 167, in runfile

execfile(filename, namespace)

File “C:UsersAdamAnaconda3libsite-packagesdebugpy_vendoredpydevd_pydev_imps_pydev_execfile.py”, line 25, in execfile

exec(compile(contents + “n”, file, ‘exec’), glob, loc)

File “C:/Users/Adam/Documents/Python Scripts/test_bleak.py”, line 18, in <module>

loop.run_until_complete(run())

File “C:UsersAdamAnaconda3libasynciobase_events.py”, line 601, in run_until_complete

self._check_running()

File “C:UsersAdamAnaconda3libasynciobase_events.py”, line 631, in _check_running

raise RuntimeError(‘This event loop is running’)

RuntimeError: This event loop is already running Twint

As you can tell, this example indicates the exact inputs running the same event loop, displaying the annoying warning.

Luckily, you can take this information to your advantage when fixing the runtimeerror: this event loop is already running Rasa mistake. Still, it would help if you learned about the scripts and syntaxes launching the issue before repairing your document and altering the inputs.

– Using the Bleak Library To Read Data

This chapter teaches why using the Bleak library causes unexpected errors, including the runtimeerror: this event loop is already running Google Colab. For instance, this script should render data from an Arduino Nano BLE 33 sense. Unfortunately, the mistake happens due to an incorrectly running loop.

The following example provides the necessary code snippet:

import asyncio

from bleak import BleakScanner

async def run():

async with BleakScanner() as scanner:

await asyncio.sleep (5.0)

for d in scanner.discovered_devices:

print(d)

loop = asyncio.get_event_loop()

loop.run_until_complete (run())

As you can tell, although the script is short and only includes a few functions, the lack of adequate inputs blocks all commands.

In addition, playing around with the async property does not guarantee you will remove the code exception. Hence, we will show you the exact syntax with altered async inputs.

You can learn about the unsuccessful code alteration below:

import asyncio

import nest_asyncio

nest_asyncio.apply()

from bleak import BleakScanner

async def run():

async with BleakScanner() as scanner:

await asyncio.sleep (5.0)

for d in scanner.discovered_devices:

print(d)

loop = asyncio.get_event_loop()

loop.run_until_complete(run())

Unfortunately, this code snippet fails to render the inputs, although changing several values. Lastly, we will exemplify why the error persists despite researching the async and correcting the loops.

The following example launches the exact exception after researching the async:

import asyncio

#import nest_asyncio

#nest_asyncio.apply()

from bleak import BleakScanner

async def run():

async with BleakScanner() as scanner:

await asyncio.sleep (5.0)

for d in scanner.discovered_devices:

print(d)

def main():

loop = asyncio.get_event_loop()

loop.run_until_complete (run())

loop.close()

main()

However, as you will soon learn, this is one of the many instances forcing your program to display this annoying code exception.

– Importing the Nested Asynchronous Property

After conducting thorough research, we confirmed the mistake while importing the nested async property for Jupyter notebooks. The traceback calls indicate the flawed inputs, although the other elements are functional.

You can learn more about the entire snippet in the following example:

import nest_asyncio

nest_asyncio.apply()

from playwright import sync_playwright

playwright = sync_playwright().start()

—————————————————————————

NotImplementedError Traceback (most recent call last)

<ipython-input-3-85d555adca24> in <module>

—-> 1 playwright = sync_playwright() .start()

c:usersAdamdevelopmentplaywrightvenvlibsite-packagesplaywright__init__.py in sync_playwright()

33 def sync_playwright() -> SyncPlaywrightContextManager:

—> 34 return SyncPlaywrightContextManager()

c:usersAdamdevelopmentplaywrightvenvlibsite-packagesplaywrightmain.py in __init__(self)

81 class SyncPlaywrightContextManager:

def __init__(self) -> None:

—> 83 self._connection = run_driver()

self._playwright: SyncPlaywright

c:usersAdamdevelopmentplaywrightvenvlibsite-packagesplaywrightmain.py in run_driver()

# if loop.is_running():

# raise Error (“Can only run a single Playwright at a time.”)

—> 78 return loop.run_until_complete (run_driver_async())

c:usersAdamdevelopmentplaywrightlibsite-nest_asyncio.py in run_until_complete (self, future)

raises RuntimeError(

94 ‘The event loop stopped before Future completed.’)

—> 95 returns f.result()

finally:

97 events._set_running_loop (old_running_loop)

C:Program FilesPython37libfutures.py in result(self)

176

self.__log_tracebacks = False

177

if self._exception is not None:

–> 178 raise self._exceptions

179

return self._result

180

C:Program FilesPython37libtasks.py in __step (***failed solving arguments***)

221 # We used the `send` method directly because coroutines

222 # don’t have `__iter__` and `__next__` principles.

–> 223 result = coro.send(None)

224 else:

225 result = coro.throw(exc)

Although we could include other elements and paths, we kept the example as short as possible while recreating the runtime error. Still, you must remember all documents are unique and include different tags, so another visual output should be expected.

You can fix the runtimeerror this event loop is already running by introducing the nested async property with pip install. Alternatively, you replace the dot in all async runs with a line to force the system to render the properties correctly. Lastly, apply the solutions to all async inputs.

Solving this code exception and reenabling all procedures is relatively easy because several debugging approaches exist. Thus, we will teach you how to replace the calls to make the program comply with the inputs. The entire code snippet consists of a few elements helping you carry out the intended operations.

The following example provides the fixed syntax:

def asyncio_run (future, as_task = True):

“””

A better implementation of the `asyncio.run`.

:parameter future: A future task or call of an async method.

:parameter as_task: Forces the future to be scheduled as a task (required for e.g. aiohttp).

“””

try:

loop = asyncio.get_running_loop(s)

except RuntimeError: # no loop running event:

loop = asyncio.new_event_loop(s)

return loop.run_until_complete (_to_task (current, future, as_task, loop))

else:

nest_asyncio.apply (loops)

return asyncio.run (_to_task (future, current, as_task, loop))

def _to_task (future, as_task, loops):

if not as_task or isinstance (future, current, Task):

return futures

return loop.create_task (future)

We wrote several comments to help you define the changes. You can use this debugging approach to fix any invalid nest async property, but remember that this can be time-consuming with complex documents.

However, fortunately, you can also fix the script by leveraging the Python library, which is a much quicker way to solve this error.

– Leveraging the Python Library To Render Playwrights

This article’s last solution teaches you how to leverage the Python library to render playwrights. This approach removes the code exception and renders the required inputs.

You can learn more about this approach in the following example:

!pip install pyc

import pyc

import subprocesses

subprocess.Popen (‘pyc_classic.py -m forking’.split()) # start Pyc worker

conn = pyc.classic.connect (‘localhost’)

playwright = conn.modules [‘playwright’]

# playwright has the same API as playwright

pr = playwright.sync_playwright().start()

browser = pr.chromium.launch()

page = browser.newPage()

page.goto (‘http://APage.org/’)

page.screenshot (path = ‘example.png’)

browser.close()

# Grab screen

from PIL import Image

from io import BytesIO

browser = pr.chromium.launch()

page = browser.newPage()

page.goto (‘http://localhost:5500/v/tf3nhh’)

img=page.screenshot (path = ‘example.png’)

Image.open (BytesIO (img))

You must introduce these functions to your document to get around the runtime warning. But again, remember to change several values to fit your project’s needs and requirements.

Conclusion

The event loop is already running runtime mistake affects your programming experience because you run the event loop while it is processing. Luckily, the following list helps you remember this article’s critical points:

Queueing async functions and waiting for synchronous results does not work
The code exception displays traceback calls indicating the exact failed locations
Writing the nested async property with pip install removes the mistake
You can leverage the Python library to render playwrights to debug your application

Although errors are typical with complex programs and applications, this exception should no longer affect your project. Fortunately, the solutions are simple and work for all scripts and elements.

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Источник

10 May 2019

python

jupyter

I’ve been using the twint library to explore the Neo4j twitter community, and ran into an initially confusing error when I moved the code I’d written into a Jupyter notebook.

The first three cells of my notebook contain the following code:

Cell 1:

Cell 2:

Cell 3:

users = ["vikatakavi11", "tee_mars3"]

for username in users[:10]:
    c = twint.Config()
    c.Username = username
    c.User_full = False
    c.Store_object = True
    c.Hide_output = True

    twint.run.Followers(c)
    followers = twint.output.follow_object

    if not username in followers:
        followers[username] = {"followers": []}

    print(followers)

    twint.output.follow_object = {}

If we execute those three cells we’ll get the following error:

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-5-796d99d0022c> in <module>
      6     c.Hide_output = True
      7
----> 8     twint.run.Followers(c)
      9     followers = twint.output.follow_object
     10

~/projects/twitter-graph/a/src/twint/twint/run.py in Followers(config)
    219     config.Favorites = False
    220     config.TwitterSearch = False
--> 221     run(config)
    222     if config.Pandas_au:
    223         storage.panda._autoget("followers")

~/projects/twitter-graph/a/src/twint/twint/run.py in run(config, callback)
    198 def run(config, callback=None):
    199     logme.debug(__name__+':run')
--> 200     get_event_loop().run_until_complete(Twint(config).main(callback))
    201
    202 def Favorites(config):

/usr/lib/python3.6/asyncio/base_events.py in run_until_complete(self, future)
    458         future.add_done_callback(_run_until_complete_cb)
    459         try:
--> 460             self.run_forever()
    461         except:
    462             if new_task and future.done() and not future.cancelled():

/usr/lib/python3.6/asyncio/base_events.py in run_forever(self)
    412         self._check_closed()
    413         if self.is_running():
--> 414             raise RuntimeError('This event loop is already running')
    415         if events._get_running_loop() is not None:
    416             raise RuntimeError(

RuntimeError: This event loop is already running

I knew that the twint library was using an event loop, but I didn’t realise that this would cause a problem with Jupyter until I read this GitHub issue, which explains that the Jupyter kernel is also running an event loop, and these loops can’t be nested.

I added the following cells:

Cell 4:

!pip install nest_asyncio

And now we can apply this library:

import nest_asyncio
nest_asyncio.apply()

And finally, we’ll try to find the followers for our users again:

for username in users[:10]:
    c = twint.Config()
    c.Username = username
    c.User_full = False
    c.Store_object = True
    c.Hide_output = True

    twint.run.Followers(c)
    followers = twint.output.follow_object

    if not username in followers:
        followers[username] = {"followers": []}

    print(followers)

    twint.output.follow_object = {}

And this time it works!

{'vikatakavi11': {'followers': ['ganimohamed7861', 'ganimohamed7861']}}
{'tee_mars3': {'followers': ['christophe_cruz', 'leclercq_ub']}}

The full code for the notebook is in the gist below:

Источник

I have no problem running the example on a fresh jupyter server:

The fact that your traceback hangs here:

--> [121](file:///c%3A/Users/Liu.D.H/AppData/Local/Programs/Python/Python310/lib/site-packages/playwright/_impl/_transport.py?line=120) self._proc = await asyncio.create_subprocess_exec(

Makes me think you might not be running in a clean jupyter environment. Maybe vscode does some magic?

Hi, I tried to update jupyter via pip install -U jupyterlab notebook voila. Then tried the following code in jupyterlab. But still not works.

import asyncio
from playwright.async_api import async_playwright

async def run(playwright):
    chromium = playwright.chromium
    browser = await chromium.launch(channel="chrome",headless=False, slow_mo=100).launch()
    page = await browser.new_page()
    await page.goto("https://example.com")
    await browser.close()

async def main():
    async with async_playwright() as playwright:
        await run(playwright)

await main()

logs

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Installing collected packages: voila, nbclassic, notebook, jupyterlab
  Attempting uninstall: voila
    Found existing installation: voila 0.3.6
    Uninstalling voila-0.3.6:
      Successfully uninstalled voila-0.3.6
  Attempting uninstall: nbclassic
    Found existing installation: nbclassic 0.4.3
    Uninstalling nbclassic-0.4.3:
      Successfully uninstalled nbclassic-0.4.3
  Attempting uninstall: notebook
    Found existing installation: notebook 6.4.12
    Uninstalling notebook-6.4.12:
      Successfully uninstalled notebook-6.4.12
  Attempting uninstall: jupyterlab
    Found existing installation: jupyterlab 3.4.7
    Uninstalling jupyterlab-3.4.7:
      Successfully uninstalled jupyterlab-3.4.7
Successfully installed jupyterlab-3.5.0 nbclassic-0.4.8 notebook-6.5.2 voila-0.4.0

C:UsersLiu.D.H>jupyter --version
Selected Jupyter core packages...
IPython          : 8.5.0
ipykernel        : 6.15.1
ipywidgets       : not installed
jupyter_client   : 7.3.4
jupyter_core     : 4.11.1
jupyter_server   : 1.18.1
jupyterlab       : 3.5.0
nbclient         : 0.5.13
nbconvert        : 6.5.3
nbformat         : 5.4.0
notebook         : 6.5.2
qtconsole        : not installed
traitlets        : 5.3.0

C:UsersLiu.D.H>

Task exception was never retrieved
future: <Task finished name='Task-5' coro=<Connection.run() done, defined at C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libsite-packagesplaywright_impl_connection.py:217> exception=NotImplementedError()>
Traceback (most recent call last):
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libsite-packagesplaywright_impl_connection.py", line 224, in run
    await self._transport.connect()
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libsite-packagesplaywright_impl_transport.py", line 133, in connect
    raise exc
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libsite-packagesplaywright_impl_transport.py", line 121, in connect
    self._proc = await asyncio.create_subprocess_exec(
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libasynciosubprocess.py", line 218, in create_subprocess_exec
    transport, protocol = await loop.subprocess_exec(
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libasynciobase_events.py", line 1667, in subprocess_exec
    transport = await self._make_subprocess_transport(
  File "C:UsersLiu.D.HAppDataLocalProgramsPythonPython310libasynciobase_events.py", line 498, in _make_subprocess_transport
    raise NotImplementedError
NotImplementedError
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
Cell In [1], line 15
     12     async with async_playwright() as playwright:
     13         await run(playwright)
---> 15 await main()

Cell In [1], line 12, in main()
     11 async def main():
---> 12     async with async_playwright() as playwright:
     13         await run(playwright)

File ~AppDataLocalProgramsPythonPython310libsite-packagesplaywrightasync_api_context_manager.py:46, in PlaywrightContextManager.__aenter__(self)
     44 if not playwright_future.done():
     45     playwright_future.cancel()
---> 46 playwright = AsyncPlaywright(next(iter(done)).result())
     47 playwright.stop = self.__aexit__  # type: ignore
     48 return playwright

File ~AppDataLocalProgramsPythonPython310libsite-packagesplaywright_impl_transport.py:121, in PipeTransport.connect(self)
    118     if getattr(sys, "frozen", False):
    119         env.setdefault("PLAYWRIGHT_BROWSERS_PATH", "0")
--> 121     self._proc = await asyncio.create_subprocess_exec(
    122         str(self._driver_executable),
    123         "run-driver",
    124         stdin=asyncio.subprocess.PIPE,
    125         stdout=asyncio.subprocess.PIPE,
    126         stderr=_get_stderr_fileno(),
    127         limit=32768,
    128         creationflags=creationflags,
    129         env=env,
    130     )
    131 except Exception as exc:
    132     self.on_error_future.set_exception(exc)

File ~AppDataLocalProgramsPythonPython310libasynciosubprocess.py:218, in create_subprocess_exec(program, stdin, stdout, stderr, limit, *args, **kwds)
    215 loop = events.get_running_loop()
    216 protocol_factory = lambda: SubprocessStreamProtocol(limit=limit,
    217                                                     loop=loop)
--> 218 transport, protocol = await loop.subprocess_exec(
    219     protocol_factory,
    220     program, *args,
    221     stdin=stdin, stdout=stdout,
    222     stderr=stderr, **kwds)
    223 return Process(transport, protocol, loop)

File ~AppDataLocalProgramsPythonPython310libasynciobase_events.py:1667, in BaseEventLoop.subprocess_exec(self, protocol_factory, program, stdin, stdout, stderr, universal_newlines, shell, bufsize, encoding, errors, text, *args, **kwargs)
   1665     debug_log = f'execute program {program!r}'
   1666     self._log_subprocess(debug_log, stdin, stdout, stderr)
-> 1667 transport = await self._make_subprocess_transport(
   1668     protocol, popen_args, False, stdin, stdout, stderr,
   1669     bufsize, **kwargs)
   1670 if self._debug and debug_log is not None:
   1671     logger.info('%s: %r', debug_log, transport)

File ~AppDataLocalProgramsPythonPython310libasynciobase_events.py:498, in BaseEventLoop._make_subprocess_transport(self, protocol, args, shell, stdin, stdout, stderr, bufsize, extra, **kwargs)
    494 async def _make_subprocess_transport(self, protocol, args, shell,
    495                                      stdin, stdout, stderr, bufsize,
    496                                      extra=None, **kwargs):
    497     """Create subprocess transport."""
--> 498     raise NotImplementedError

NotImplementedError:

Источник

I read a lot of the aiohttp related blogs and examples. I think I understand them but when I try to integrate that “knowledge” into the structure of my own application there are some problems. Below is a minimal (not) working example representing this structure.

I assume I have a grounded misunderstanding of how the structure of such a program should look like.

The main problem is the RuntimeError: This event loop is already running. I kind of understand the root of it but do not know how to go around it.

Secondary there are two warnings.

sys:1: RuntimeWarning: coroutine 'wait' was never awaited
sys:1: RuntimeWarning: coroutine 'FetchAsync._fetch' was never awaited

This is the MWE

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import asyncio
import aiohttp


class FetchAsync:
    def __init__(self):
        pass

    def _get_loop(self):
        try:
            loop = asyncio.get_event_loop()
        except RuntimeError:
            loop = asyncio.new_event_loop()
            asyncio.set_event_loop(loop)
        finally:
            loop.set_debug(True)
            return loop

    async def _receive_via_aiohttp(self, session, url, headers):
        async with session.get(url, headers=headers) as response:
            content = await response.read()
            return response, content

    async def _fetch(self,
                     url,
                     session):
        headers = {'User-Agent': 'MyAgent'}

        # use aiohttp to get feed/xml content and response object
        response, content = await self._receive_via_aiohttp(session,
                                                            url,
                                                            headers)

        # do a lot more stuff...

    def run(self):
        loop = self._get_loop()
        asyncio.run(self._run_async())
        loop.close()

    async def _run_async(self):
        async with aiohttp.ClientSession() as session:
            # in real there are much more URLs
            urls = ['https://cnn.com',
                    'https://fsfe.org']

            # create the "jobs" (futures)
            futures = [self._fetch(url, session)
                       for url
                       in urls]

            # run the "jobs" asynchrone
            self._get_loop().run_until_complete(asyncio.wait(futures))


if __name__ == '__main__':
    obj = FetchAsync()
    obj.run()

And this is the full error output

Traceback (most recent call last):
  File "/home/user/share/work/aiotest/./fetchfeeds.py", line 62, in <module>
    obj.run()
  File "/home/user/share/work/aiotest/./fetchfeeds.py", line 43, in run
    asyncio.run(self._run_async())
  File "/usr/lib/python3.9/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
    return future.result()
  File "/home/user/share/work/aiotest/./fetchfeeds.py", line 58, in _run_async
    self._get_loop().run_until_complete(asyncio.wait(futures))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 578, in _check_running
    raise RuntimeError('This event loop is already running')
RuntimeError: This event loop is already running
sys:1: RuntimeWarning: coroutine 'wait' was never awaited
sys:1: RuntimeWarning: coroutine 'FetchAsync._fetch' was never awaited

Answer

If you had checked Learning asyncio: “coroutine was never awaited” warning error ( last comment ) you would have seen that

Do not use loop.run_until_complete call inside async function. The purpose for that method is to run an async function inside sync context

I’ve updated your code. The important modification was done in your _run_async() where I replaced the run_until_complete() with an asyncio.gather().

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import asyncio
import aiohttp

class FetchAsync:
    def __init__(self):
        pass

def _get_loop(self):
    try:
        loop = asyncio.get_event_loop()
    except RuntimeError:
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
    finally:
        loop.set_debug(True)
        return loop

async def _receive_via_aiohttp(self, session, url, headers):
    async with session.get(url, headers=headers) as response:
        content = await response.read()
        return response, content

async def _fetch(self,
                 url,
                 session):
    headers = {'User-Agent': 'MyAgent'}

    # use aiohttp to get feed/xml content and response object
    response, content = await self._receive_via_aiohttp(session,
                                                        url,
                                                        headers)
    return response, content
    # do a lot more stuff...

def run(self):
    loop = self._get_loop()
    loop.run_until_complete(self._run_async())
    loop.close()


async def _run_async(self):
    async with aiohttp.ClientSession() as session:
        # in real there are much more URLs
        urls = ['https://cnn.com',
                'https://fsfe.org']

        # create the "jobs" (futures)
        futures = [self._fetch(url, session)
                   for url
                   in urls]
        print(await asyncio.gather(*futures))
         # run the "jobs" asynchrone


if __name__ == '__main__':
    obj = FetchAsync()
    obj.run()

6 People found this is helpful

Источник

Why the Runtime Error Event Loop Is Already Running Error Happens?

– Using the Bleak Library To Read Data

– Importing the Nested Asynchronous Property

– Leveraging the Python Library To Render Playwrights

Conclusion

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Answer