What are async context managers for HTTP sessions?

Question

Accepted Answer

**Async HTTP sessions** use context managers for **connection pooling**.

```python
import asyncio
import aiohttp

# Single session for multiple requests
async def fetch_all(urls):
    async with aiohttp.ClientSession() as session:
        tasks = [fetch_one(session, url) for url in urls]
        return await asyncio.gather(*tasks)

async def fetch_one(session, url):
    async with session.get(url) as response:
        return await response.json()

# Custom async context manager
from contextlib import asynccontextmanager

@asynccontextmanager
async def api_client(base_url):
    async with aiohttp.ClientSession(base_url=base_url) as session:
        yield ApiWrapper(session)

class ApiWrapper:
    def __init__(self, session):
        self.session = session

async def get(self, path):
        async with self.session.get(path) as resp:
            return await resp.json()

# Usage
async def main():
    async with api_client("https://api.example.com") as api:
        data = await api.get("/users")
        print(data)

asyncio.run(main())
```

**Benefits:**
- Connection reuse.
- Automatic cleanup.
- Session-level settings.

Python: What are async context managers for HTTP sessions?