[FIXED] await till the end of exectuion of dynamically generated async code in python

Issue

I am creating an async python function during runtime. It can be created as a plain string / python ast object. Then I execute the code using exec().

I want to run the generated code and wait till the execution ends for it. I generate the function, and then inejcting code so that the final code looks like this-

import asyncio

async def my_app():
    # some async calls etc

loop = asyncio.get_event_loop()
task = loop.create_task(my_app())

In my caller code, I am doing

exec(my_code)
await asyncio.sleep(0)

I was having trouble doing await my_app() in the python code (caller is already an async function). According to my understanding, the sleep(0) gives control to the event loop to process other tasks. But I am not sure how this will work out if the code generated makes multiple async calls (which it possibly will). How to assure the exectuon finished.

Solution

If you really do need to: generate an async function, exec it in a namespace, grab the reference to the function, and run it as usual.

import asyncio

generated_code = """
import asyncio

async def my_app():
    print("hello!")
    await asyncio.sleep(1)
    print("hoi!")
    # some async calls etc

"""


async def go():
    ns = {}
    exec(generated_code, ns)
    my_task = asyncio.create_task(ns["my_app"]())
    await my_task


asyncio.run(go())

EDIT: Re the comments; instead of global variables, pass in an object to modify (a dataclass here for brevity's sake):

import asyncio
from dataclasses import dataclass

generated_code = """
import asyncio

async def my_app(state):
    print("hello!")
    state.age *= 2
    state.name = state.name[::-1]
    await asyncio.sleep(1)
    print("hoi!")

"""


@dataclass
class MyState:
    name: str
    age: int


async def go():
    state = MyState(name="Arthur", age=42)
    ns = {}
    exec(generated_code, ns)
    print("State before", state)
    my_task = asyncio.create_task(ns["my_app"](state))
    await my_task
    print("State after", state)


asyncio.run(go())

This outputs

State before MyState(name='Arthur', age=42)
hello!
hoi!
State after MyState(name='ruhtrA', age=84)

Answered By - AKX