Tasks & Concurrency — Series 2

Preview — 3 of 10 questions

What is the output of the following code?

javascript

import asyncio

async def main():
    result = await asyncio.gather()
    print(result)

asyncio.run(main())

A[]

BTypeError: gather() missing 1 required positional argument

CThe program hangs forever waiting for at least one awaitable.

DNone

What is the output of the following code?

javascript

import asyncio

async def quick():
    await asyncio.sleep(0.01)
    return "quick done"

async def slow():
    await asyncio.sleep(0.2)
    return "slow done"

async def main():
    t1 = asyncio.create_task(quick())
    t2 = asyncio.create_task(slow())
    done, pending = await asyncio.wait({t1, t2}, timeout=0.05)
    print(len(done), len(pending))
    print(list(done)[0].result())

asyncio.run(main())

A2 0, quick done — asyncio.wait ignores the timeout argument unless every awaitable has already finished.

B1 1, quick done

C0 2, TypeError: 'set' object has no attribute 'result' — neither task has completed by the time the timeout elapses.

D1 1, slow done

What is the output of the following code?

javascript

import asyncio

async def compute():
    await asyncio.sleep(0.05)
    return "computed"

async def main():
    task = asyncio.create_task(compute())
    print(task.done())
    await asyncio.sleep(0.1)
    print(task.done())
    print(task.result())

asyncio.run(main())

ATrue, True, computed — a Task is immediately marked done the instant it's created.

BFalse, False, TypeError: result is not ready

CFalse, True, computed

DFalse, True, <coroutine object compute at 0x...> — .result() returns the underlying coroutine rather than its resolved value.

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