tests/extmod/asyncio_fair.py


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# Test fairness of scheduler

try:
    import asyncio
except ImportError:
    print("SKIP")
    raise SystemExit


async def task(id, t):
    print("task start", id)
    while True:
        if t > 0:
            print("task work", id)
        await asyncio.sleep(t)


async def main():
    t1 = asyncio.create_task(task(1, -0.01))
    t2 = asyncio.create_task(task(2, 0.1))
    t3 = asyncio.create_task(task(3, 0.18))
    t4 = asyncio.create_task(task(4, -100))
    await asyncio.sleep(0.45)  # t2 prints 5 times, t3 prints 3 times
    t1.cancel()
    t2.cancel()
    t3.cancel()
    t4.cancel()
    print("finish")


asyncio.run(main())