Problems with event_loops in Python 3.10

Question

I try to get data from the Binance Websocket. With python 3.9 as Interpreter it runs fine, but with 3.10 it gives me errors :(

Here is the code:

import asyncio
from binance import AsyncClient, BinanceSocketManager


async def main():
    client = await AsyncClient.create()
    bm = BinanceSocketManager(client)
    # start any sockets here, i.e a trade socket
    ts = bm.trade_socket('BNBBTC')
    # then start receiving messages
    async with ts as tscm:
        while True:
            res = await tscm.recv()
            print(res)


if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

I get this error:

DeprecationWarning: There is no current event loop
  loop = asyncio.get_event_loop()

I use PyCharm as IDE.

Anyone there who can help me, please?

It's not an error, it's a warning. https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.get_event_loop — Jan Christoph Terasa, Oct 26 '21 at 19:05

Jan Christoph Terasa · Answer 1 · 2021-10-26T22:51:25.030

10

This is a deprecation warning, that means the behaviour of the function get_event_loop() you called will soon change, in that it will no longer create a new event loop, but rather raise RuntimeError like get_running_loop. From the looks of it the intended way is to create a new event loop explicitly rather than implicitly.

if __name__ == "__main__":
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(main())

I am not sure if asyncio.set_event_loop(loop) is actually necessary.

edited Oct 26 '21 at 22:51

answered Oct 26 '21 at 19:52

Jan Christoph Terasa

5,781
24
34

`get_event_loop` itself isn't deprecated. The deprecation applies to calling it when no loop is running. In a future version of Python doing so will raise a `RuntimeError`. – dirn Oct 26 '21 at 21:10
That's true, I will fix the wording. – Jan Christoph Terasa Oct 26 '21 at 22:50
2

`asyncio.set_event_loop(loop)` is not necessary here. – jxn Feb 25 '22 at 21:12

score 2 · Answer 2 · answered Oct 26 '21 at 20:08

2

The recommended api for running even loop is asyncio.run (introduced in Python 3.7).

The example can be modified to adopt it:


if __name__ == "__main__":
    asyncio.run(main())

answered Oct 26 '21 at 20:08

Andrew Svetlov

16,730
8
66
69

but if I do so in a other script I will get what I want but then I get RuntimError: Event loop is closed – Max Power Apr 07 '22 at 08:42

Problems with event_loops in Python 3.10

2 Answers2