uasyncio.create_task does not run coroutine (micropython)

Question

Before I start an issue on github, just wanted to know, if I am doing smth wrong. This basic example should start a loop and after one calls the stop method it should stop. However, the print("while loop") gets not executed at all.

rp2040 Zero (Pico)
Thonny IDE

import uasyncio
import utime

class Test:
    def __init__(self):
        pass
    
    def run_loop(self):
        self.should_run = 1
        uasyncio.create_task(self._while_loop())

    async def _while_loop(self):
        print("while loop") # <--------- gets never called!
        counter = 0
        while self.should_run == 1:
            counter += 1
            print(counter)
            await uasyncio.sleep_ms(100)
    
    def stop(self):
        self.should_run = 0
        print("should stop now")

test = Test()
test.run_loop()
print("looop started.. wait..")
utime.sleep(3)
print("...waited..")
test.stop()

webdeb · Accepted Answer · 2023-01-02 13:29:30Z

In a python script all executions are sync by default. To provide async functionality one has to create an async context. this is done via asyncio.run() // which will wait due to pythons nature till all inner async tasks are terminated.

As the micropython-uasyncio docs says, a typical async application is wrapped into the async context (e.g. main function).

This is how I solved the problem above:

import uasyncio as asyncio
import utime

class Test:
    run = 0
    def __init__(self):
        pass
    
    def run_loop(self):
        self.run = 1
        asyncio.create_task(self._while_loop())

    async def _while_loop(self):
        print("while loop, should_run:", self.run)
        counter = 0
        while self.run == 1:
            counter += 1
            print(counter)
            await asyncio.sleep_ms(100)

    def stop(self):
        self.run = 0
        print("should stop now")

async def main():
    test = Test()
    test.run_loop()
    print("looop started.. wait..")
    await asyncio.sleep(2)
    test.stop()

asyncio.run(main())

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