await asyncio.sleep

Learn waiting with await asyncio.sleep.

await asyncio.sleep

asyncio.sleep is the async counterpart of time.sleep. It waits a given duration without blocking the event loop; other coroutines can run in the meantime.

async def task():
    print("start")
    await asyncio.sleep(0)
    print("end")

Here await asyncio.sleep(0) yields control to the event loop so other coroutines can run. The control point applies even with zero seconds.

time.sleep instead freezes the whole program; that's why it is not used in async code.

Waiting and control points

When a coroutine reaches an await point, it yields control to the event loop. The loop moves to another pending coroutine. This is the basis of the concurrent appearance.

Wait times are in seconds; they can be fractional. await asyncio.sleep(0.5) waits half a second. Even with zero, control is yielded.

This model gives high concurrency even under the GIL: while waiting on I/O, other work happens.

Exercise Write task with await asyncio.sleep

Start with import asyncio. The function async def task() first prints print("start"), then await asyncio.sleep(0), finally print("end") and return "ok". Add print(asyncio.run(task())).

Show example solution

import asyncio

async def task():
    print("start")
    await asyncio.sleep(0)
    print("end")
    return "ok"

print(asyncio.run(task()))

Test yourself

Why is time.sleep not used in async code?
- Because it is slower
- Because it raises errors
- Because it blocks the event loop
- Because it only works on Windows
Show answer

Because it blocks the event loop — time.sleep freezes the whole program; other coroutines cannot run.

asyncio.sleep call

import asyncio

async def task():
    await ____(0)

Show answer

import asyncio

async def task():
    await asyncio.sleep(0)

Match the sleep concepts

asyncio.sleep

Non-blocking wait
time.sleep

Blocks
await asyncio.sleep(0)

Control point
await asyncio.sleep(0.5)

Half a second

Next lesson: create_task

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies