Async chores

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examples/async/async_chores.py

import time
import asyncio

async def boil_water(sec):
    print(f"Start boiling water for {sec} seconds")
    await asyncio.sleep(sec)
    print(f"End boiling water for {sec} seconds")

async def washing_machine(sec):
    print(f"Start washing machine for {sec} seconds")
    await asyncio.sleep(sec)
    print(f"End washing machine for {sec} seconds")
    await dryer(3)

async def dryer(sec):
    print(f"Start dryer for {sec} seconds")
    await asyncio.sleep(sec)
    print(f"End dryer for {sec} seconds")

async def dishwasher(sec):
    print(f"Start dishwasher for {sec} seconds")
    await asyncio.sleep(sec)
    print(f"End dishwasher for {sec} seconds")

async def clean_potatoes(pieces):
    print(f"Start cleaning potatoes for {pieces} pieces")
    for ix in range(pieces):
        print(f"Cleaning potato {ix}")
        time.sleep(0.5)
        #await asyncio.sleep(0.0001)
    print(f"End cleaning potatoes for {pieces} pieces")

async def main():
    await asyncio.gather(
        dishwasher(3),
        washing_machine(3),
        boil_water(4),
        clean_potatoes(14))

start = time.time()
asyncio.run(main())
end = time.time()
print(f"Elapsed {end-start}")

From the output you can see that we noticed that the washing machine has finished only after we have finished all the potatoes. That's becasue our potato cleaning process was a long-running CPU-intensive process. This means the dryer only starts working after the potatoes are clean.

Start dishwasher for 3 seconds
Start washing machine for 3 seconds
Start boiling water for 4 seconds
Start cleaning potatoes for 14 pieces
Cleaning potato 0
Cleaning potato 1
Cleaning potato 2
Cleaning potato 3
Cleaning potato 4
Cleaning potato 5
Cleaning potato 6
Cleaning potato 7
Cleaning potato 8
Cleaning potato 9
Cleaning potato 10
Cleaning potato 11
Cleaning potato 12
Cleaning potato 13
End cleaning potatoes for 14 pieces
End dishwasher for 3 seconds
End washing machine for 3 seconds
Start dryer for 3 seconds
End boiling water for 4 seconds
End dryer for 3 seconds
Elapsed 10.01340126991272

If after cleaning each potato we look up for a fraction of a second, if we let the main loop run, then we can notice that the washing machine has ended and we can turn on the dryer before continuing with the next potato. This will allow the dryer to work while we are still cleaning the potatoes.

Start dishwasher for 3 seconds
Start washing machine for 3 seconds
Start boiling water for 4 seconds
Start cleaning potatoes for 14 pieces
Cleaning potato 0
Cleaning potato 1
Cleaning potato 2
Cleaning potato 3
Cleaning potato 4
Cleaning potato 5
End dishwasher for 3 seconds
End washing machine for 3 seconds
Start dryer for 3 seconds
Cleaning potato 6
Cleaning potato 7
End boiling water for 4 seconds
Cleaning potato 8
Cleaning potato 9
Cleaning potato 10
Cleaning potato 11
End dryer for 3 seconds
Cleaning potato 12
Cleaning potato 13
End cleaning potatoes for 14 pieces
Elapsed 7.02296781539917