In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Add the background task { #add-the-background-task }

Neste caso, a função da tarefa escreverá em um arquivo (simulando o envio de um e-mail).

E como a operação de escrita não usa `async` e `await`, definimos a função com um `def` normal:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Adicione a tarefa em segundo plano { #add-the-background-task }

        )

    tasks.add_task(bg, state)
    return state


@app.middleware("http")
async def middleware(request, call_next):
    response: StreamingResponse = await call_next(request)
    response.headers["x-state"] = json.dumps(state.copy())
    return response


client = TestClient(app)


def test_async_state():

                logger.error("Failed to update suggest index.", t);
                exitCode.set(1);
                latch.countDown();
            });

            try {
                latch.await();
            } catch (final InterruptedException ignore) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Interrupted.", ignore);
                }
                exitCode.set(1);

      }
    }
  }

  /**
   * Cleans up the given reference and any other references already in the queue. Catches and logs
   * all throwables.
   *
   * @return true if the caller should continue to wait for more references to be added to the
   *     queue, false if the associated FinalizableReferenceQueue is no longer referenced.
   */
  private boolean cleanUp(Reference<?> firstReference) {

백그라운드 작업으로 실행할 함수를 정의합니다.

이것은 단순히 매개변수를 받을 수 있는 표준 함수일 뿐입니다.

**FastAPI**는 이것이 `async def` 함수이든, 일반 `def` 함수이든 내부적으로 이를 올바르게 처리합니다.

이 경우, 아래 작업은 파일에 쓰는 함수입니다. (이메일 보내기 시물레이션)

그리고 이 작업은 `async`와 `await`를 사용하지 않으므로 일반 `def` 함수로 선언합니다.

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## 백그라운드 작업 추가

_경로 작동 함수_ 내에서 작업 함수를 `.add_task()` 함수 통해 _백그라운드 작업_ 개체에 전달합니다.

        TestResource resource = new TestResource("old");
        resourceManager.registerResource(resource);

        assertFalse(resource.isClosed());

        // Wait for automatic cleanup to kick in
        Thread.sleep(300);

        // Perform cleanup
        resourceManager.performCleanup();

        // Old resource should be auto-closed

 *       next task will wait for any running callable (or pending {@code Future} returned by an
 *       {@code AsyncCallable}) to complete, without interrupting it (and without calling {@code
 *       cancel} on the {@code Future}). So beware: <i>Even if you cancel every preceding {@code
 *       Future} returned by this class, the next task may still have to wait.</i>.

			}
		}
	}()

	return objs, nil
}

// Close and release resources.
func (w *metacacheWriter) Close() error {
	if w == nil || w.closer == nil {
		return nil
	}
	w.streamWg.Wait()
	err := w.closer()
	w.closer = nil
	return err
}

// Reset and start writing to new writer.
// Close must have been called before this.
func (w *metacacheWriter) Reset(out io.Writer) {

                    }
                }
            });
        }

        // Start all threads
        for (Thread thread : threads) {
            thread.start();
        }

        // Wait for all threads to complete
        for (Thread thread : threads) {
            thread.join();
        }

        // Verify results
        assertTrue(exceptions.isEmpty());