Stop using asyncio.get_event_loop()

It is deprecated in newer Python versions.
Closes #4013.

readthedocs/concepts/asyncio.rst

@@ -40,22 +40,22 @@ because tasks are smaller than threads, which are smaller than processes.
 What are asyncio basics?
 ========================
 
+The code samples below assume that you have Python 3.7 or greater installed.
+
 .. code-block:: python
 
     # First we need the asyncio library
     import asyncio
 
-    # Then we need a loop to work with
-    loop = asyncio.get_event_loop()
-
     # We also need something to run
     async def main():
         for char in 'Hello, world!\n':
             print(char, end='', flush=True)
             await asyncio.sleep(0.2)
 
-    # Then, we need to run the loop with a task
-    loop.run_until_complete(main())
+    # Then, we can create a new asyncio loop and use it to run our coroutine.
+    # The creation and tear-down of the loop is hidden away from us.
+    asyncio.run(main())
 
 
 What does telethon.sync do?
@@ -101,7 +101,7 @@ Instead of this:
 
     # or, using asyncio's default loop (it's the same)
     import asyncio
-    loop = asyncio.get_event_loop()  # == client.loop
+    loop = asyncio.get_running_loop()  # == client.loop
     me = loop.run_until_complete(client.get_me())
     print(me.username)
 
@@ -158,13 +158,10 @@ loops or use ``async with``:
 
                 print(message.sender.username)
 
-    loop = asyncio.get_event_loop()
-    # ^ this assigns the default event loop from the main thread to a variable
-
-    loop.run_until_complete(main())
-    # ^ this runs the *entire* loop until the main() function finishes.
-    #   While the main() function does not finish, the loop will be running.
-    #   While the loop is running, you can't run it again.
+    asyncio.run(main())
+    # ^ this will create a new asyncio loop behind the scenes and tear it down
+    #   once the function returns. It will run the loop untiil main finishes.
+    #   You should only use this function if there is no other loop running.
 
 
 The ``await`` keyword blocks the *current* task, and the loop can run
@@ -184,14 +181,14 @@ concurrently:
         await asyncio.sleep(delay)  # await tells the loop this task is "busy"
         print('world')  # eventually the loop finishes all tasks
 
-    loop = asyncio.get_event_loop()  # get the default loop for the main thread
-    loop.create_task(world(2))  # create the world task, passing 2 as delay
-    loop.create_task(hello(delay=1))  # another task, but with delay 1
+    async def main():
+        asyncio.create_task(world(2))  # create the world task, passing 2 as delay
+        asyncio.create_task(hello(delay=1))  # another task, but with delay 1
+        await asyncio.sleep(3)  # wait for three seconds before exiting
+
     try:
-        # run the event loop forever; ctrl+c to stop it
-        # we could also run the loop for three seconds:
-        #     loop.run_until_complete(asyncio.sleep(3))
-        loop.run_forever()
+        # create a new temporary asyncio loop and use it to run main
+        asyncio.run(main())
     except KeyboardInterrupt:
         pass
 
@@ -209,10 +206,15 @@ The same example, but without the comment noise:
         await asyncio.sleep(delay)
         print('world')
 
-    loop = asyncio.get_event_loop()
-    loop.create_task(world(2))
-    loop.create_task(hello(1))
-    loop.run_until_complete(asyncio.sleep(3))
+    async def main():
+        asyncio.create_task(world(2))
+        asyncio.create_task(hello(delay=1))
+        await asyncio.sleep(3)
+
+    try:
+        asyncio.run(main())
+    except KeyboardInterrupt:
+        pass
 
 
 Can I use threads?
@@ -250,9 +252,9 @@ You may have seen this error:
 
     RuntimeError: There is no current event loop in thread 'Thread-1'.
 
-It just means you didn't create a loop for that thread, and if you don't
-pass a loop when creating the client, it uses ``asyncio.get_event_loop()``,
-which only works in the main thread.
+It just means you didn't create a loop for that thread. Please refer to
+the ``asyncio`` documentation to correctly learn how to set the event loop
+for non-main threads.
 
 
 client.run_until_disconnected() blocks!

readthedocs/concepts/updates.rst

@@ -191,8 +191,7 @@ so the code above and the following are equivalent:
     async def main():
         await client.disconnected
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
 
 You could also run `client.disconnected

readthedocs/misc/changelog.rst

@@ -2088,7 +2088,7 @@ the scenes! This means you're now able to do both of the following:
     async def main():
       await client.send_message('me', 'Hello!')
 
-    asyncio.get_event_loop().run_until_complete(main())
+    asyncio.run(main())
 
     # ...can be rewritten as:
 

readthedocs/misc/compatibility-and-convenience.rst

@@ -161,19 +161,17 @@ just get rid of ``telethon.sync`` and work inside an ``async def``:
 
             await client.run_until_disconnected()
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
 
-The ``telethon.sync`` magic module simply wraps every method behind:
+The ``telethon.sync`` magic module essentially wraps every method behind:
 
 .. code-block:: python
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
-So that you don't have to write it yourself every time. That's the
-overhead you pay if you import it, and what you save if you don't.
+With some other tricks, so that you don't have to write it yourself every time.
+That's the overhead you pay if you import it, and what you save if you don't.
 
 Learning
 ========

telethon/client/telegrambaseclient.py

@@ -192,7 +192,7 @@ class TelegramBaseClient(abc.ABC):
             Defaults to `lang_code`.
 
         loop (`asyncio.AbstractEventLoop`, optional):
-            Asyncio event loop to use. Defaults to `asyncio.get_event_loop()`.
+            Asyncio event loop to use. Defaults to `asyncio.get_running_loop()`.
             This argument is ignored.
 
         base_logger (`str` | `logging.Logger`, optional):
@@ -470,7 +470,7 @@ class TelegramBaseClient(abc.ABC):
                 # Join the task (wait for it to complete)
                 await task
         """
-        return asyncio.get_event_loop()
+        return helpers.get_running_loop()
 
     @property
     def disconnected(self: 'TelegramClient') -> asyncio.Future:

telethon/events/inlinequery.py

@@ -4,7 +4,7 @@ import re
 import asyncio
 
 from .common import EventBuilder, EventCommon, name_inner_event
-from .. import utils
+from .. import utils, helpers
 from ..tl import types, functions, custom
 from ..tl.custom.sendergetter import SenderGetter
 
@@ -242,6 +242,6 @@ class InlineQuery(EventBuilder):
             if inspect.isawaitable(obj):
                 return asyncio.ensure_future(obj)
 
-            f = asyncio.get_event_loop().create_future()
+            f = helpers.get_running_loop().create_future()
             f.set_result(obj)
             return f

telethon/helpers.py

@@ -426,7 +426,10 @@ class _FileStream(io.IOBase):
 # endregion
 
 def get_running_loop():
-    if sys.version_info[:2] <= (3, 6):
-        return asyncio._get_running_loop()
-
-    return asyncio.get_running_loop()
+    if sys.version_info >= (3, 7):
+        try:
+            return asyncio.get_running_loop()
+        except RuntimeError:
+            return asyncio.get_event_loop_policy().get_event_loop()
+    else:
+        return asyncio.get_event_loop()

telethon/network/connection/connection.py

@@ -155,7 +155,7 @@ class Connection(abc.ABC):
 
                 # Actual TCP connection is performed here.
                 await asyncio.wait_for(
-                    asyncio.get_event_loop().sock_connect(sock=sock, address=address),
+                    helpers.get_running_loop().sock_connect(sock=sock, address=address),
                     timeout=timeout
                 )
 
@@ -190,7 +190,7 @@ class Connection(abc.ABC):
 
             # Actual TCP connection and negotiation performed here.
             await asyncio.wait_for(
-                asyncio.get_event_loop().sock_connect(sock=sock, address=address),
+                helpers.get_running_loop().sock_connect(sock=sock, address=address),
                 timeout=timeout
             )
 
@@ -244,7 +244,7 @@ class Connection(abc.ABC):
         await self._connect(timeout=timeout, ssl=ssl)
         self._connected = True
 
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         self._send_task = loop.create_task(self._send_loop())
         self._recv_task = loop.create_task(self._recv_loop())
 

telethon/network/mtprotosender.py

@@ -68,7 +68,7 @@ class MTProtoSender:
         # pending futures should be cancelled.
         self._user_connected = False
         self._reconnecting = False
-        self._disconnected = asyncio.get_event_loop().create_future()
+        self._disconnected = helpers.get_running_loop().create_future()
         self._disconnected.set_result(None)
 
         # We need to join the loops upon disconnection
@@ -261,7 +261,7 @@ class MTProtoSender:
             await self._disconnect(error=e)
             raise e
 
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         self._log.debug('Starting send loop')
         self._send_loop_handle = loop.create_task(self._send_loop())
 
@@ -400,7 +400,7 @@ class MTProtoSender:
                 self._pending_state.clear()
 
                 if self._auto_reconnect_callback:
-                    asyncio.get_event_loop().create_task(self._auto_reconnect_callback())
+                    helpers.get_running_loop().create_task(self._auto_reconnect_callback())
 
                 break
         else:
@@ -425,7 +425,7 @@ class MTProtoSender:
             # gets stuck.
             # TODO It still gets stuck? Investigate where and why.
             self._reconnecting = True
-            asyncio.get_event_loop().create_task(self._reconnect(error))
+            helpers.get_running_loop().create_task(self._reconnect(error))
 
     def _keepalive_ping(self, rnd_id):
         """

telethon/sync.py

@@ -14,7 +14,7 @@ import asyncio
 import functools
 import inspect
 
-from . import events, errors, utils, connection
+from . import events, errors, utils, connection, helpers
 from .client.account import _TakeoutClient
 from .client.telegramclient import TelegramClient
 from .tl import types, functions, custom
@@ -32,7 +32,7 @@ def _syncify_wrap(t, method_name):
     @functools.wraps(method)
     def syncified(*args, **kwargs):
         coro = method(*args, **kwargs)
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         if loop.is_running():
             return coro
         else:

telethon_examples/gui.py

@@ -53,7 +53,7 @@ def callback(func):
     def wrapped(*args, **kwargs):
         result = func(*args, **kwargs)
         if inspect.iscoroutine(result):
-            aio_loop.create_task(result)
+            asyncio.create_task(result)
 
     return wrapped
 
@@ -369,10 +369,4 @@ async def main(interval=0.05):
 
 
 if __name__ == "__main__":
-    # Some boilerplate code to set up the main method
-    aio_loop = asyncio.get_event_loop()
-    try:
-        aio_loop.run_until_complete(main())
-    finally:
-        if not aio_loop.is_closed():
-            aio_loop.close()
+    asyncio.run(main())

telethon_examples/interactive_telegram_client.py

@@ -9,9 +9,6 @@ from telethon.errors import SessionPasswordNeededError
 from telethon.network import ConnectionTcpAbridged
 from telethon.utils import get_display_name
 
-# Create a global variable to hold the loop we will be using
-loop = asyncio.get_event_loop()
-
 
 def sprint(string, *args, **kwargs):
     """Safe Print (handle UnicodeEncodeErrors on some terminals)"""
@@ -50,7 +47,7 @@ async def async_input(prompt):
     let the loop run while we wait for input.
     """
     print(prompt, end='', flush=True)
-    return (await loop.run_in_executor(None, sys.stdin.readline)).rstrip()
+    return (await asyncio.get_running_loop().run_in_executor(None, sys.stdin.readline)).rstrip()
 
 
 def get_env(name, message, cast=str):
@@ -109,34 +106,34 @@ class InteractiveTelegramClient(TelegramClient):
         # media known the message ID, for every message having media.
         self.found_media = {}
 
+    async def init(self):
         # Calling .connect() may raise a connection error False, so you need
         # to except those before continuing. Otherwise you may want to retry
         # as done here.
         print('Connecting to Telegram servers...')
         try:
-            loop.run_until_complete(self.connect())
+            await self.connect()
         except IOError:
             # We handle IOError and not ConnectionError because
             # PySocks' errors do not subclass ConnectionError
             # (so this will work with and without proxies).
             print('Initial connection failed. Retrying...')
-            loop.run_until_complete(self.connect())
+            await self.connect()
 
         # If the user hasn't called .sign_in() or .sign_up() yet, they won't
         # be authorized. The first thing you must do is authorize. Calling
         # .sign_in() should only be done once as the information is saved on
         # the *.session file so you don't need to enter the code every time.
-        if not loop.run_until_complete(self.is_user_authorized()):
+        if not await self.is_user_authorized():
             print('First run. Sending code request...')
             user_phone = input('Enter your phone: ')
-            loop.run_until_complete(self.sign_in(user_phone))
+            await self.sign_in(user_phone)
 
             self_user = None
             while self_user is None:
                 code = input('Enter the code you just received: ')
                 try:
-                    self_user =\
-                        loop.run_until_complete(self.sign_in(code=code))
+                    self_user = await self.sign_in(code=code)
 
                 # Two-step verification may be enabled, and .sign_in will
                 # raise this error. If that's the case ask for the password.
@@ -146,8 +143,7 @@ class InteractiveTelegramClient(TelegramClient):
                     pw = getpass('Two step verification is enabled. '
                                  'Please enter your password: ')
 
-                    self_user =\
-                        loop.run_until_complete(self.sign_in(password=pw))
+                    self_user = await self.sign_in(password=pw)
 
     async def run(self):
         """Main loop of the TelegramClient, will wait for user action"""
@@ -397,9 +393,14 @@ class InteractiveTelegramClient(TelegramClient):
                 ))
 
 
-if __name__ == '__main__':
+async def main():
     SESSION = os.environ.get('TG_SESSION', 'interactive')
     API_ID = get_env('TG_API_ID', 'Enter your API ID: ', int)
     API_HASH = get_env('TG_API_HASH', 'Enter your API hash: ')
     client = InteractiveTelegramClient(SESSION, API_ID, API_HASH)
-    loop.run_until_complete(client.run())
+    await client.init()
+    await client.run()
+
+
+if __name__ == '__main__':
+    asyncio.run()

telethon_examples/payment.py

@@ -7,8 +7,6 @@ import os
 import time
 import sys
 
-loop = asyncio.get_event_loop()
-
 """
 Provider token can be obtained via @BotFather. more info at https://core.telegram.org/bots/payments#getting-a-token
 
@@ -180,4 +178,4 @@ if __name__ == '__main__':
     if not provider_token:
         logger.error("No provider token supplied.")
         exit(1)
-    loop.run_until_complete(main())
+    asyncio.run(main())

telethon_examples/quart_login.py

@@ -1,7 +1,6 @@
 import base64
 import os
 
-import hypercorn.asyncio
 from quart import Quart, render_template_string, request
 
 from telethon import TelegramClient, utils
@@ -82,6 +81,8 @@ async def format_message(message):
 # Connect the client before we start serving with Quart
 @app.before_serving
 async def startup():
+    # After connecting, the client will create additional asyncio tasks that run until it's disconnected again.
+    # Be careful to not mix different asyncio loops during a client's lifetime, or things won't work properly!
     await client.connect()
 
 
@@ -129,24 +130,11 @@ async def root():
     return await render_template_string(BASE_TEMPLATE, content=CODE_FORM)
 
 
-async def main():
-    await hypercorn.asyncio.serve(app, hypercorn.Config())
-
-
 # By default, `Quart.run` uses `asyncio.run()`, which creates a new asyncio
-# event loop. If we create the `TelegramClient` before, `telethon` will
-# use `asyncio.get_event_loop()`, which is the implicit loop in the main
-# thread. These two loops are different, and it won't work.
+# event loop. If we had connected the `TelegramClient` before, `telethon` will
+# use `asyncio.get_running_loop()` to create some additional tasks. If these
+# loops are different, it won't work.
 #
-# So, we have to manually pass the same `loop` to both applications to
-# make 100% sure it works and to avoid headaches.
-#
-# To run Quart inside `async def`, we must use `hypercorn.asyncio.serve()`
-# directly.
-#
-# This example creates a global client outside of Quart handlers.
-# If you create the client inside the handlers (common case), you
-# won't have to worry about any of this, but it's still good to be
-# explicit about the event loop.
+# To keep things simple, be sure to not create multiple asyncio loops!
 if __name__ == '__main__':
-    client.loop.run_until_complete(main())
+    app.run()