asyncio + multithreading: one asyncio event loop per thread

asyncio_loops.py

import asyncio
import threading
import random


def thr(i):
    # we need to create a new loop for the thread, and set it as the 'default'
    # loop that will be returned by calls to asyncio.get_event_loop() from this
    # thread.
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)

    loop.run_until_complete(do_stuff(i))
    loop.close()


async def do_stuff(i):
    await asyncio.sleep(random.uniform(0.1, 0.5)) # NOTE if we hadn't called
        # asyncio.set_event_loop() earlier, we would have to pass an event
        # loop to this function explicitly.
    print(i)


def main():
    num_threads = 10
    threads = [ threading.Thread(target = thr, args=(i,)) for i in range(num_threads) ]
    [ t.start() for t in threads ]
    [ t.join() for t in threads ]
    print("bye")


if __name__ == "__main__":
    main()