async def contextmanager_in_threadpool(
    cm: AbstractContextManager[_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:

///

En Python, puedes crear Context Managers <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">creando una clase con dos métodos: `__enter__()` y `__exit__()`</a>.

También puedes usarlos dentro de las dependencias de **FastAPI** con `yield` usando
`with` o `async with` en la función de dependencia:

{* ../../docs_src/dependencies/tutorial010_py39.py hl[1:9,13] *}

这是一个更为"高级"的想法。

如果你刚开始使用 **FastAPI** ，你可以暂时可以跳过它。

///

在Python中，你可以通过<a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">创建一个带有`__enter__()`和`__exit__()`方法的类</a>来创建上下文管理器。

你也可以在 **FastAPI** 的 `yield` 依赖项中通过 `with` 或者 `async with` 语句来使用它们：

{* ../../docs_src/dependencies/tutorial010.py hl[1:9,13] *}

/// tip | 提示

另一种创建上下文管理器的方法是：

**FastAPI** を使い始めたばかりの方は、とりあえずスキップした方がよいかもしれません。

///

Pythonでは、<a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">以下の２つのメソッドを持つクラスを作成する: `__enter__()`と`__exit__()`</a>ことでコンテキストマネージャを作成することができます。

また、依存関数の中で`with`や`async with`文を使用することによって`yield`を持つ **FastAPI** の依存関係の中でそれらを使用することができます:

{* ../../docs_src/dependencies/tutorial010.py hl[1,2,3,4,5,6,7,8,9,13] *}

/// tip | 豆知識

///

В Python можно создавать менеджеры контекста, <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">создав класс с двумя методами: `__enter__()` и `__exit__()`</a>.

Их также можно использовать внутри зависимостей **FastAPI** с `yield`, применяя операторы
`with` или `async with` внутри функции зависимости:

{* ../../docs_src/dependencies/tutorial010_py39.py hl[1:9,13] *}

///

In Python können Sie Kontextmanager erstellen, indem Sie <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">eine Klasse mit zwei Methoden erzeugen: `__enter__()` und `__exit__()`</a>.

Sie können solche auch innerhalb von **FastAPI**-Abhängigkeiten mit `yield` verwenden, indem Sie `with`- oder `async with`-Anweisungen innerhalb der Abhängigkeits-Funktion verwenden:

///

Em Python, você pode criar Gerenciadores de Contexto ao <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">criar uma classe com dois métodos: `__enter__()` e `__exit__()`</a>.

Você também pode usá-los dentro de dependências com `yield` do **FastAPI** ao utilizar
`with` ou `async with` dentro da função da dependência:

{* ../../docs_src/dependencies/tutorial010_py39.py hl[1:9,13] *}

///

In Python, you can create Context Managers by <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">creating a class with two methods: `__enter__()` and `__exit__()`</a>.

You can also use them inside of **FastAPI** dependencies with `yield` by using
`with` or `async with` statements inside of the dependency function:

///

Python에서는 다음을 통해 컨텍스트 관리자를 생성할 수 있습니다. <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank"> 두 가지 메서드가 있는 클래스를 생성합니다: `__enter__()` and `__exit__()`</a>.

**FastAPI**의 `yield`가 있는 의존성 내에서
`with` 또는 `async with`문을 사용하여 이들을 활용할 수 있습니다:

{* ../../docs_src/dependencies/tutorial010.py hl[1:9,13] *}

/// tip | 팁

컨텍스트 관리자를 생성하는 또 다른 방법은 다음과 같습니다: