* interned, and so does not prevent these instances from being garbage-collected. This most
   * likely does not perform as well as {@link #newStrongInterner}, but is the best alternative when
   * the memory usage of that implementation is unacceptable.
   */
  @GwtIncompatible // java.lang.ref.WeakReference
  public static <E> Interner<E> newWeakInterner() {
    return newBuilder().weak().build();

Dans certains cas, vous pouvez vouloir surcharger la logique utilisée par les classes `Request` et `APIRoute`.

En particulier, cela peut être une bonne alternative à une logique dans un middleware.

Par exemple, si vous voulez lire ou manipuler le corps de la requête avant qu'il ne soit traité par votre application.

/// danger | Danger

Ceci est une fonctionnalité « avancée ».

# Clase personalizada de Request y APIRoute { #custom-request-and-apiroute-class }

En algunos casos, puede que quieras sobrescribir la lógica utilizada por las clases `Request` y `APIRoute`.

En particular, esta puede ser una buena alternativa a la lógica en un middleware.

Por ejemplo, si quieres leer o manipular el request body antes de que sea procesado por tu aplicación.

/// danger | Advertencia

Esta es una funcionalidad "avanzada".

The class `BackgroundTasks` comes directly from [`starlette.background`](https://www.starlette.dev/background/).

It is imported/included directly into FastAPI so that you can import it from `fastapi` and avoid accidentally importing the alternative `BackgroundTask` (without the `s` at the end) from `starlette.background`.

Have a simple and easy to use routing system.

///

### [Requests](https://requests.readthedocs.io) { #requests }

**FastAPI** is not actually an alternative to **Requests**. Their scope is very different.

It would actually be common to use Requests *inside* of a FastAPI application.

But still, FastAPI got quite some inspiration from Requests.

     * below, we actually run the AbstractFutureTest methods under that scenario.
     */
    checkHelperVersion(NO_ATOMIC_REFERENCE_FIELD_UPDATER, "SynchronizedHelper");

    // Then, run the actual tests under each alternative classloader:

    /*
     * We don't need to test further under NO_UNSAFE: We verified that it selects
     * AtomicReferenceFieldUpdaterAtomicHelper, which is the default, which means that it's used

   * href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/package-summary.html#Spurious">
   * fail spuriously</a> and does not provide ordering guarantees, so is only rarely an appropriate
   * alternative to {@code compareAndSet}.
   *
   * @param expect the expected value
   * @param update the new value
   * @return {@code true} if successful
   */

        Cell a = as[i];
        if (a != null) sum += a.value;
      }
    }
    return sum;
  }

  /**
   * Resets variables maintaining the sum to zero. This method may be a useful alternative to
   * creating a new adder, but is only effective if there are no concurrent updates. Because this
   * method is intrinsically racy, it should only be used when it is known that no threads are
   * concurrently updating.

    checkHelperVersion(NO_UNSAFE, "AtomicReferenceFieldUpdaterAtomicHelper");
    checkHelperVersion(NO_ATOMIC_REFERENCE_FIELD_UPDATER, "SynchronizedHelper");

    // Then, run the actual tests under each alternative classloader:

    /*
     * Under Java 8, there is no need to test the no-VarHandle case here: It's already tested by the
     * main AbstractFutureTest, which uses the default AtomicHelper, which we verified above to be

Ela é importada/incluída diretamente no FastAPI para que você possa importá-la de `fastapi` e evitar importar acidentalmente a alternativa `BackgroundTask` (sem o `s` no final) de `starlette.background`.