# 이벤트: startup과 shutdown

필요에 따라 응용 프로그램이 시작되기 전이나 종료될 때 실행되는 이벤트 핸들러(함수)를 정의할 수 있습니다.

이 함수들은 `async def` 또는 평범하게 `def`으로 선언할 수 있습니다.

!!! warning "경고"
    이벤트 핸들러는 주 응용 프로그램에서만 작동합니다. [하위 응용 프로그램 - 마운트](./sub-applications.md){.internal-link target=_blank}에서는 작동하지 않습니다.

## `startup` 이벤트

응용 프로그램을 시작하기 전에 실행하려는 함수를 "startup" 이벤트로 선언합니다:

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

    final CountDownLatch started = new CountDownLatch(1);
    FakeService service =
        new FakeService() {
          @Override
          protected void startUp() throws Exception {
            super.startUp();
            started.await();
          }
        };
    service.startAsync();
    service.stopAsync();
    started.countDown();
    service.awaitTerminated();

[19515] [INFO] Booting worker with pid: 19515
[19511] [INFO] Started server process [19511]
[19511] [INFO] Waiting for application startup.
[19511] [INFO] Application startup complete.
[19513] [INFO] Started server process [19513]
[19513] [INFO] Waiting for application startup.
[19513] [INFO] Application startup complete.
[19514] [INFO] Started server process [19514]
[19514] [INFO] Waiting for application startup.
[19514] [INFO] Application startup complete.

    **FastAPI** 只执行主应用中的事件处理器，不执行[子应用 - 挂载](sub-applications.md){.internal-link target=_blank}中的事件处理器。

## `startup` 事件

使用 `startup` 事件声明 `app` 启动前运行的函数：

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

本例中，`startup` 事件处理器函数为项目数据库（只是**字典**）提供了一些初始值。

**FastAPI** 支持多个事件处理器函数。

只有所有 `startup` 事件处理器运行完毕，**FastAPI** 应用才开始接收请求。

## `shutdown` 事件

使用 `shutdown` 事件声明 `app` 关闭时运行的函数：

  public void testStart_failed() {
    final Exception exception = new Exception("deliberate");
    TestService service =
        new TestService() {
          @Override
          protected void startUp() throws Exception {
            super.startUp();
            throw exception;
          }
        };
    assertEquals(0, service.startUpCalled);
    RuntimeException e =

[19515] [INFO] Booting worker with pid: 19515
[19511] [INFO] Started server process [19511]
[19511] [INFO] Waiting for application startup.
[19511] [INFO] Application startup complete.
[19513] [INFO] Started server process [19513]
[19513] [INFO] Waiting for application startup.
[19513] [INFO] Application startup complete.
[19514] [INFO] Started server process [19514]
[19514] [INFO] Waiting for application startup.
[19514] [INFO] Application startup complete.

### Run Automatically on Startup

In general, you will probably want the server program (e.g. Uvicorn) to be started automatically on server startup, and without needing any **human intervention**, to have a process always running with your API (e.g. Uvicorn running your FastAPI app).

### Separate Program

    final CountDownLatch started = new CountDownLatch(1);
    FakeService service =
        new FakeService() {
          @Override
          protected void startUp() throws Exception {
            super.startUp();
            started.await();
          }
        };
    service.startAsync();
    service.stopAsync();
    started.countDown();
    service.awaitTerminated();

        }
      };

  /** Constructor for use by subclasses. */
  protected AbstractExecutionThreadService() {}

  /**
   * Start the service. This method is invoked on the execution thread.
   *
   * <p>By default this method does nothing.
   */
  protected void startUp() throws Exception {}

  /**
   * Run the service. This method is invoked on the execution thread. Implementations must respond

Essas funções podem ser declaradas com `async def` ou `def` normal.

### Evento `startup`

Para adicionar uma função que deve rodar antes da aplicação iniciar, declare-a com o evento `"startup"`:

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

Nesse caso, a função de manipulação de evento `startup` irá inicializar os itens do "banco de dados" (só um `dict`) com alguns valores.