Python async vs Node.js async: how to execute an async function in Python and then continue until async is done?

Question

I have the following script written in both js and python. However, I cannot get the python script to work.

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

async function get_burgers() {
  console.log("Just ordered...");
  console.log("Making burgers");
  await sleep(3000);
  console.log("Burgers ready!");
  console.log("Eating them...");
}

async function main() {
  console.log("Walking into restaurant...");
  console.log("Ordering...");
  get_burgers();
  console.log("Talking, talking, talking...");
}

main();

This outputs:

Walking into restaurant...
Ordering...
Just ordered...
Making burgers
Talking, talking, talking...
Burgers ready!
Eating them...

This is the same script in Python using asyncio

import asyncio


async def get_burgers():
    print("Just ordered...")
    print("Making burgers...")
    await asyncio.sleep(5)
    print("Burgers ready!")
    print("Eating burgers")


async def main():
    print("Walking into store with crush")
    print("Ordering....")
    await asyncio.gather(get_burgers())
    print("Talking, talking, talking...")


asyncio.run(main())

This blocks and prints Talking, talking, talking... last. When I remove the await before asyncio.gather(get_burgers()) it crashes. How would I make the python script give the result as the node.js script?

AKX · Accepted Answer · 2022-09-06 11:27:04Z

3

The Python async model is a bit different – you'd need to do

import asyncio


async def get_burgers():
    print("Just ordered...")
    print("Making burgers...")
    await asyncio.sleep(5)
    print("Burgers ready!")
    print("Eating burgers")


async def chat_while_waiting_for_burgers():
    print("Talking, talking, talking...")


async def main():
    print("Walking into store with crush")
    print("Ordering....")
    await asyncio.gather(get_burgers(), chat_while_waiting_for_burgers())


asyncio.run(main())

so the output is

Walking into store with crush
Ordering....
Just ordered...
Making burgers...
Talking, talking, talking...
Burgers ready!
Eating burgers

answered Sep 6, 2022 at 11:27

AKX

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3 Comments

adir abargil Over a year ago

there isn’t a way to fire the function without awaiting it?

AKX Over a year ago

@adirabargil You can call the function, but you do need to await for it eventually. There is no implicit loop like there is in Node.js that would "pump" all "remaining" coros.

dirn Over a year ago

You can create a task and await it at the end, but there is fire-and-forget behavior. The loop only runs as long as you’re awaiting something.

Henro Sutrisno Tanjung · Accepted Answer · 2022-09-06 11:49:23Z

0

may be also you can use _thread module

import _thread
import time

def get_burgers(x):
    print("Just ordered...")
    print("Making burgers...")
    time.sleep(5)
    print("Burgers ready!")
    print("Eating burgers")
    print("Eating them")


def main(x):
    print("Walking into store with crush")
    print("Ordering....")
    _thread.start_new_thread( get_burgers, ("Thread-1", ) )
    time.sleep(5)
    print("Talking, talking, talking...")


try:
   _thread.start_new_thread( main, ("Thread-1", ) )
except:
   print ("Error: unable to start thread")

while 1:
   pass

output:

Walking into store with crush
Ordering....
Just ordered...
Making burgers...
Talking, talking, talking...
Burgers ready!
Eating burgers
Eating them

answered Sep 6, 2022 at 11:49

Henro Sutrisno Tanjung

5304 silver badges6 bronze badges

3 Comments

AKX Over a year ago

OP is explicitly asking about async, not threads. Additionally, if you want to use threads, you should never use _thread directly, but threading.

Henro Sutrisno Tanjung Over a year ago

@AKX, he asking how to get with same result in python. CMIIW

AKX Over a year ago

They could get the same result without async or threading, but that's not the point. The title says "Python async", and the post says "The same script using Python asyncio".

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