async def contextmanager_in_threadpool(
    cm: ContextManager[_T],
) -> AsyncGenerator[_T, None]:
    # blocking __exit__ from running waiting on a free thread
    # can create race conditions/deadlocks if the context manager itself
    # has its own internal pool (e.g. a database connection pool)
    # to avoid this we let __exit__ run without a capacity limit
    # since we're creating a new limiter for each call, any non-zero limit

class MySuperContextManager:
    def __init__(self):
        self.db = DBSession()

    def __enter__(self):
        return self.db

    def __exit__(self, exc_type, exc_value, traceback):
        self.db.close()


async def get_db():
    with MySuperContextManager() as db:

		{unescaped: "for", escaped: "__for__"},
		{unescaped: "function", escaped: "__function__"},
		{unescaped: "if", escaped: "__if__"},
		{unescaped: "import", escaped: "__import__"},
		{unescaped: "let", escaped: "__let__"},
		{unescaped: "loop", escaped: "__loop__"},
		{unescaped: "package", escaped: "__package__"},
		{unescaped: "namespace", escaped: "__namespace__"},
		{unescaped: "return", escaped: "__return__"},

    🚥 👆 ▶️ ⏮️ **FastAPI** 👆 💪 💚 🚶 ⚫️ 🔜.

🐍, 👆 💪 ✍ 🔑 👨‍💼 <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">🏗 🎓 ⏮️ 2️⃣ 👩‍🔬: `__enter__()` &amp; `__exit__()`</a>.

👆 💪 ⚙️ 👫 🔘 **FastAPI** 🔗 ⏮️ `yield` ⚙️
`with` ⚖️ `async with` 📄 🔘 🔗 🔢:

```Python hl_lines="1-9  13"
{!../../../docs_src/dependencies/tutorial010.py!}
```

!!! tip