private void addUtilityTasks(TaskContainer tasks, GradleDocumentationExtension extension) {
        tasks.register("serveDocs", ServeDocs.class, task -> {
            task.setDescription("Runs a local webserver to serve generated documentation.");
            task.setGroup("documentation");

            int webserverPort = 8000;
            task.getJavaLauncher().set(

```Python hl_lines="6-9"
{!../../docs_src/background_tasks/tutorial001.py!}
```

## バックグラウンドタスクの追加

*path operations 関数* 内で、`.add_task()` メソッドを使用してタスク関数を *background tasks* オブジェクトに渡します。

```Python hl_lines="14"
{!../../docs_src/background_tasks/tutorial001.py!}
```

`.add_task()` は以下の引数を受け取ります:

* バックグラウンドで実行されるタスク関数 (`write_notification`)。
* タスク関数に順番に渡す必要のある引数の列 (`email`)。

            task.setGroup("release notes");
            task.setDescription("Generate release notes HTML page from Markdown.");

            task.getInputEncoding().convention(Charset.defaultCharset().name());
            task.getOutputEncoding().convention(Charset.defaultCharset().name());

        ObjectFactory objects = project.getObjects();
        // TODO: This breaks if version is changed later
        Object version = project.getVersion();

        TaskProvider<Javadoc> javadocAll = tasks.register("javadocAll", Javadoc.class, task -> {
            task.setGroup("documentation");
            task.setDescription("Generate Javadocs for all API classes");

 * cancelled).
 *
 * <p>This class serializes execution of <i>submitted</i> tasks but not any <i>listeners</i> of
 * those tasks.
 *
 * <p>Submitted tasks have a happens-before order as defined in the Java Language Specification.
 * Tasks execute with the same happens-before order that the function calls to {@link #submit} and
 * {@link #submitAsync} that submitted those tasks had.
 *

        TaskProvider<Docbook2Xhtml> dslHtml = tasks.register("dslHtml", Docbook2Xhtml.class, task -> {
            task.setGroup("documentation");
            task.setDescription("Generates DSL reference HTML documentation.");
            task.onlyIf(t -> !extension.getQuickFeedback().get());

            task.source(dslStandaloneDocbook);
            task.getStylesheetDirectory().convention(dslReference.getStylesheetDirectory());

   * is running when that time is reached, that task is allowed to complete before this task is
   * started. Similarly the task will be delayed if the host lacks compute resources.
   *
   * @throws RejectedExecutionException if the queue is shut down and the task is not cancelable.
   */
  fun schedule(
    task: Task,
    delayNanos: Long = 0L,
  ) {
    taskRunner.lock.withLock {
      if (shutdown) {

    Preconditions.checkNotNull(task, "task must not be null!");
    return delegate.submit(task);
  }

  @Override
  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
      throws InterruptedException {
    Preconditions.checkNotNull(tasks, "tasks must not be null!");
    return delegate.invokeAll(tasks);
  }

  @Override
  public <T> List<Future<T>> invokeAll(

    Preconditions.checkNotNull(task, "task must not be null!");
    return delegate.submit(task);
  }

  @Override
  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
      throws InterruptedException {
    Preconditions.checkNotNull(tasks, "tasks must not be null!");
    return delegate.invokeAll(tasks);
  }

  @Override
  public <T> List<Future<T>> invokeAll(

  private static class FakeExecutor implements Executor {
    Queue<Runnable> tasks = Queues.newArrayDeque();

    @Override
    public void execute(Runnable command) {
      tasks.add(command);
    }

    boolean hasNext() {
      return !tasks.isEmpty();
    }

    void runNext() {
      assertTrue("expected at least one task to run", hasNext());
      tasks.remove().run();
    }

    void runAll() {