Python Asyncio ile Asenkron Programlama

Asyncio Neden

IO-bound islemlerde (ag, disk) thread kullanmak yerine asyncio ile tek thread'de binlerce eszamanli islem yapilabilir.

Temel Coroutine

import asyncio

async def selamla(isim: str, bekleme: float) -> str:
    await asyncio.sleep(bekleme)
    return f'Merhaba, {isim}!'

async def main():
    sonuc = await selamla('Emre', 1.0)
    print(sonuc)

asyncio.run(main())

Paralel Islemler

async def main():
    # Sirayla: 3 saniye
    # await selamla('A', 1)
    # await selamla('B', 2)

    # Paralel: 2 saniye (en uzun kadar)
    sonuclar = await asyncio.gather(
        selamla('A', 1),
        selamla('B', 2),
        selamla('C', 0.5),
    )
    print(sonuclar)

HTTP Istekleri

import aiohttp
import asyncio

async def url_getir(session: aiohttp.ClientSession, url: str) -> dict:
    async with session.get(url) as yanit:
        return {'url': url, 'durum': yanit.status, 'boyut': len(await yanit.text())}

async def main():
    urls = [
        'https://httpbin.org/delay/1',
        'https://httpbin.org/delay/2',
        'https://httpbin.org/get',
    ]
    async with aiohttp.ClientSession() as session:
        gorevler = [url_getir(session, u) for u in urls]
        sonuclar = await asyncio.gather(*gorevler)
        for s in sonuclar:
            print(f"{s['url']}: {s['durum']} ({s['boyut']} byte)")

asyncio.run(main())

Timeout ve Hata Yonetimi

async def guvenli_getir(url: str) -> str | None:
    try:
        async with asyncio.timeout(5.0):
            async with aiohttp.ClientSession() as s:
                async with s.get(url) as r:
                    return await r.text()
    except asyncio.TimeoutError:
        print(f'Timeout: {url}')
        return None
    except Exception as e:
        print(f'Hata: {e}')
        return None

asyncio, Python'da yuksek performansli IO islemleri icin guclu bir araçtir.