/// note | 技術細節

一個 `async` 任務只能在抵達某個 `await` 時才能被取消。如果沒有 `await`，該產生器（帶有 `yield` 的函式）將無法被正確取消，甚至在請求取消後仍可能持續執行。

因為這個小範例不需要任何 `await` 陳述式，我們加入 `await anyio.sleep(0)`，讓事件迴圈有機會處理取消。

對於大型或無限的串流來說，這點更為重要。

///

/// tip

與其直接回傳 `StreamingResponse`，你大概會想遵循[資料串流](./stream-data.md)中的作法，這樣更方便，並且會在底層幫你處理取消。

				logger.Info("Waiting for AuthN to be initialized.. (retrying in %s)", retryInterval)
			}
			if !authZInit {
				logger.Info("Waiting for AuthZ to be initialized.. (retrying in %s)", retryInterval)
			}
			time.Sleep(retryInterval)
			continue
		}

		break
	}

	// Initialize IAM store
	sys.Lock()

	sys.initStore(objAPI, etcdClient)

	// Initialize RoleARNs

      }

      OverrideParam.ReadTimeout -> {
        client =
          client
            .newBuilder()
            .socketFactory(
              DelayingSocketFactory(onRead = {
                Thread.sleep(100L)
              }),
            ).build()

        overrideBadImplementation(override = override.override, testItFails = testItFails)
      }

      OverrideParam.ConnectTimeout -> {
        client =

    // Service b startup takes at least 353 millis, but starting the timer is delayed by at least
    // 150 milliseconds. so in a perfect world the timing would be 353-150=203ms, but since either
    // of our sleep calls can be arbitrarily delayed we should just assert that there is a time
    // recorded.
    assertThat(startupTimes.get(b)).isNotNull();
  }

  public void testServiceStartStop() {

                    String command;
                    while (true) {
                        try {
                            while (!reader.ready()) {
                                ThreadUtil.sleep(1000L);
                            }
                            command = reader.readLine().trim();
                            if (logger.isDebugEnabled()) {

	user.Age = 20
	if err := DB.Create(&user).Error; err != nil {
		t.Errorf("failed to create user, got error %v", err)
	}

	var user2 User
	DB.First(&user2, user.ID)
	user2.Age = 30
	time.Sleep(time.Second)
	if err := DB.Clauses(clause.OnConflict{UpdateAll: true}).Create(&user2).Error; err != nil {
		t.Fatalf("failed to onconflict create user, got error %v", err)
	} else {
		var user3 User
		DB.First(&user3, user.ID)

			<-ctx.Done()
			return
		}
		duration := max(time.Duration(r.Float64()*float64(time.Minute)),
			// Make sure to sleep at least a second to avoid high CPU ticks.
			time.Second)
		time.Sleep(duration)
	}
}

// Loads bucket replication resync statuses into memory.

    assertThat(server.takeRequest().exchangeIndex).isEqualTo(0)

    // Give the server time to enact the socket policy if it's one that could happen after the
    // client has received the response.
    Thread.sleep(500)
    val response2 = getResponse(newRequest("/b"))
    response1.body
      .source()
      .timeout()
      .timeout(100, TimeUnit.MILLISECONDS)

   * (IOException) e.getCause()} throws a {@link ClassCastException} that discards the original
   * exception {@code e} if the cause is not an {@link IOException}, but {@code
   * Throwables.getCauseAs(e, IOException.class)} keeps {@code e} as the {@link
   * ClassCastException}'s cause.
   *
   * @throws ClassCastException if the cause cannot be cast to the expected type. The {@code
   *     ClassCastException}'s cause is {@code throwable}.

Those two tasks are what **consume time the most**. That's the main work of maintaining FastAPI.

If you can help me with that, **you are helping me maintain FastAPI** and making sure it keeps **advancing faster and better**. 🚀

## Join the chat { #join-the-chat }

Join the 👥 [Discord chat server](https://discord.gg/VQjSZaeJmf) 👥 and hang out with others in the FastAPI community.

/// tip