Event Loop Internals — Series 3

Preview — 3 of 10 questions

What is the output of the following code?

javascript

import asyncio

async def main():
    sem = asyncio.BoundedSemaphore(2)
    await sem.acquire()
    await sem.acquire()
    sem.release()
    sem.release()
    try:
        sem.release()
    except ValueError as e:
        print("ValueError:", e)

asyncio.run(main())

AValueError: BoundedSemaphore released too many times

BNo error — the semaphore's internal count simply keeps increasing

CRuntimeError: semaphore already at maximum value

DNothing happens; the third release() call is silently ignored

What is the output of the following code?

javascript

import asyncio
import time

def blocking_work():
    time.sleep(0.05)
    return "done"

async def main():
    loop = asyncio.get_running_loop()
    result = await loop.run_in_executor(None, blocking_work)
    print(result)

asyncio.run(main())

ARuntimeError: blocking_work() cannot be called from an executor

Bdone

CTypeError: run_in_executor() missing 1 required positional argument

DA coroutine object prints instead of the string, since run_in_executor() doesn't actually wait for completion

What is the output of the following code?

javascript

import asyncio

async def worker():
    return 1

async def main():
    coro = worker()
    task = asyncio.create_task(coro)
    print(asyncio.iscoroutine(coro))
    print(asyncio.iscoroutine(task))
    await task

asyncio.run(main())

AFalse, True

BFalse, False

CTrue, False

DTrue, True

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