await asyncio.sleep

Concurrency & Async

Meaning

Suspends the current coroutine for a specified number of seconds while yielding control back to the event loop so other tasks can execute. It addresses the problem of blocking the entire event loop with a synchronous delay, which would freeze all concurrent coroutines. Reach for it whenever you need a non-blocking pause, such as throttling requests, simulating latency in tests, or implementing retry backoff.

Primary Function

Async control flow

Communicative Purpose

Introduce a non-blocking delay or yield point in asynchronous code.

Pattern

await asyncio.sleep(duration)

Core Structure

await asyncio.sleep(...)

Função primária

Async control flow

Propósito comunicativo

Introduce a non-blocking delay or yield point in asynchronous code.

Situações de gatilho

Testing: simulating network latency or slow I/O in async unit tests. Web scraping: throttling requests to avoid rate-limiting. Retry logic: implementing exponential backoff between failed attempts.

Contextos

Python asyncio applications, web scrapers, async web servers, network clients.

Padrão

await asyncio.sleep(duration)

Estrutura central

await asyncio.sleep(...)

Slots de substituição

duration: numeric seconds (float or int)

Colocados típicos

async def
await
asyncio.create_task
asyncio.gather
asyncio.wait_for

Substituições comuns

asyncio.sleep(0) to yield control
use asyncio.wait_for for timeout
use asyncio.sleep for exponential backoff

Erros comuns

Using time.sleep instead of asyncio.sleep: misconception that any sleep works in async code → blocks the event loop, freezing all concurrent coroutines; Forgetting the await keyword: syntax oversight → coroutine object is created but never awaited, delay is silently skipped; Passing a non-numeric duration: type error → raises TypeError at runtime.

Similar / contraste

time.sleep(1) – blocking synchronous sleep; asyncio.wait_for(task, timeout) – waits with timeout; asyncio.sleep(0) – yields control without delay.

Interferências

Coming from threading or languages with blocking sleep: may incorrectly use time.sleep, which halts the entire event loop.

Família do chunk

asyncio.sleep
asyncio.wait
asyncio.shield
asyncio.gather

Nuance

The delay is a minimum; actual resumption may be later if the event loop is busy. Not suitable for precise timing or real‑time scheduling.

Efeito pragmático

Prevents blocking, allows other coroutines to progress, making async programs responsive.

Dica de memória

Imagine your coroutine taking a coffee break.

Nota

Remember that the delay is a minimum; actual resume time depends on event loop load.

Upgrade path

Use asyncio.wait_for with a timeout, or implement exponential backoff with asyncio.sleep(2**attempt).

Frequência: HighFormulaicidade: Semi-fixedTipo de construção: async delay constructPrioridade de aquisição: Active recallPrioridade de output: BothTag de espaçamento: Medium-term

Examples

import asyncio async def main(): print("Start") await asyncio.sleep(1) print("After 1 second") asyncio.run(main())

import asyncio async def worker(name): for i in range(3): print(f"{name} step {i}") await asyncio.sleep(0) # yield to event loop async def main(): await asyncio.gather(worker("A"), worker("B")) asyncio.run(main())

import asyncio import random async def fetch_with_retry(url, max_attempts=5): for attempt in range(1, max_attempts + 1): try: if random.choice([True, False]): return f"Data from {url}" raise ConnectionError("Failed") except ConnectionError: if attempt == max_attempts: raise delay = 2 ** attempt await asyncio.sleep(delay) async def main(): result = await fetch_with_retry("http://example.com") print(result) asyncio.run(main())