[FIXED] asyncio, this event loop is already running issue

Issue

is it a good idea to run the asyncio eventloop inside a thread?

import asyncio
import time
from sample_threading import parallel
loop = asyncio.new_event_loop()

async def fn(p):
  for i in range(5):
    print(i)
    time.sleep(5)
  print("done")


@parallel
def th(p):
   loop.run_until_complete(fn(p))

th(1)
th(2)
th(3)

above code giving error

raise RuntimeError('This event loop is already running')
RuntimeError: This event loop is already running

any suggestion ?

Solution

error message you are haveing, This event loop is already running, is beacuse when you attempt to run an asyncio event loop that is already running. In your code, you are creating a new event loop using asyncio.new_event_loop(), but you are not explicitly setting it as the current event loop.

import asyncio
import time
from sample_threading import parallel

async def fn(p):
    for i in range(5):
        print(i)
        # instead of time.sleep, you ensure that the sleep operation is non- 
        # blocking and allows other tasks to run concurrently.
        await asyncio.sleep(5)
    print("done")

@parallel
def th(p):
    asyncio.run(fn(p))

th(1)
th(2)
th(3)

Running the asyncio event loop inside a thread can be a valid approach in certain scenarios, especially when you need to perform asynchronous tasks concurrently with other operations.

Answered By - Sauron