Python asyncio: Mastering Async/Await Programming

Async programming in Python lets you handle thousands of concurrent operations without threads. Here's how to use asyncio effectively.

Complete Code Example

import asyncio
import httpx
from datetime import datetime

# Basic async function
async def fetch_price(symbol: str) -> float:
    async with httpx.AsyncClient() as client:
        r = await client.get(
            "https://api.binance.com/api/v3/ticker/price",
            params={"symbol": f"{symbol}USDT"}
        )
        return float(r.json()["price"])

# Running multiple tasks concurrently
async def fetch_all_prices():
    symbols = ["BTC", "ETH", "SOL", "BNB"]
    # Run all requests at the same time!
    prices = await asyncio.gather(*[fetch_price(s) for s in symbols])
    return dict(zip(symbols, prices))

# Async context manager
class AsyncTimer:
    async def __aenter__(self):
        self.start = datetime.now()
        return self

    async def __aexit__(self, *args):
        elapsed = (datetime.now() - self.start).total_seconds()
        print(f"Elapsed: {elapsed:.3f}s")

async def main():
    async with AsyncTimer():
        prices = await fetch_all_prices()
        for symbol, price in prices.items():
            print(f"{symbol}: ${price:,.2f}")

asyncio.run(main())

# Async generator
async def count_up(n: int):
    for i in range(n):
        await asyncio.sleep(0.01)  # simulate async work
        yield i

async def use_generator():
    async for value in count_up(5):
        print(value)

💡 Pro Tips

• Use asyncio.gather() to run multiple coroutines concurrently
• Never use time.sleep() in async code — use asyncio.sleep() instead
• httpx is the best async HTTP library for Python

Why This Matters

Understanding these Python features will help you write more:

• ✅ Readable and maintainable code
• ✅ Memory-efficient applications
• ✅ Pythonic, idiomatic solutions

Summary

Mastering Python's built-in features is key to becoming a better developer. Practice these examples in your own projects, and you'll quickly see the benefits.

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