Tasks & Concurrency — Series 3

Preview — 3 of 10 questions

What is the output of the following code?

javascript

import asyncio

async def main():
    q = asyncio.Queue(maxsize=2)
    q.put_nowait(1)
    q.put_nowait(2)
    try:
        q.put_nowait(3)
    except asyncio.QueueFull:
        print("QueueFull")

    print(q.get_nowait())
    print(q.get_nowait())
    try:
        q.get_nowait()
    except asyncio.QueueEmpty:
        print("QueueEmpty")

asyncio.run(main())

AQueueFull, 1, 2, QueueEmpty

B1, 2, 3, QueueEmpty

CQueueFull, 1, 2, 3

DQueueFull, 2, 1, QueueEmpty

What is the output of the following code?

javascript

import asyncio

async def fail():
    raise ValueError("bad")

async def main():
    task = asyncio.create_task(fail())
    await asyncio.sleep(0.01)
    print(task.done())
    try:
        task.result()
    except ValueError as e:
        print("ValueError:", e)

asyncio.run(main())

ATrue, ValueError: bad, then the program crashes anyway once main() returns

BTrue, ValueError: bad

CFalse, ValueError: bad

DTrue, None

What is the output of the following code?

javascript

import asyncio

async def worker(n, delay):
    await asyncio.sleep(delay)
    return n

async def main():
    t1 = asyncio.create_task(worker(1, 0.05))
    t2 = asyncio.create_task(worker(2, 0.3))
    done, pending = await asyncio.wait([t1, t2], timeout=0.1)
    print(len(done), len(pending))
    print(t1 in done)
    print(t2 in pending)
    t2.cancel()

asyncio.run(main())

A0 2, False, True

B1 1, False, False

C1 1, True, True

D2 0, True, False

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