{* ../../docs_src/background_tasks/tutorial001_py39.py hl[1,13] *}

**FastAPI** создаст объект типа `BackgroundTasks` для вас и передаст его через этот параметр.

## Создание функции для фоновой задачи { #create-a-task-function }

Создайте функцию, которую нужно запустить как фоновую задачу.

Это обычная функция, которая может принимать параметры.

  private final ExecutionList executionList = new ExecutionList();

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code
   * Callable}.
   *
   * @param callable the callable task
   * @since 10.0
   */
  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
    return new ListenableFutureTask<>(callable);
  }

  /**

        setupPluginRequirements()
    }

    /**
     * Create projects and files required for plugins applied to the project (including transitively applied plugins).
     * These files are not required to run the task itself, but are required to apply the binary-compatibility plugin.
     */
    protected
    fun setupPluginRequirements() {

      }

      @Override
      public ListenableFuture<V> reload(K key, V oldValue) {
        ListenableFutureTask<V> task =
            ListenableFutureTask.create(() -> loader.reload(key, oldValue).get());
        executor.execute(task);
        return task;
      }

      @Override
      public Map<K, V> loadAll(Iterable<? extends K> keys) throws Exception {
        return loader.loadAll(keys);

Directory for ReplaceSchema task

replace-schema-*.sql:
DDL statements for creation of your schema.
You should write your own DDL statements in this file.
(A SQL separator is semicolon ";")

take-finally-*.sql:
SQL statements for check loaded data (or DDL after data loading)
You should write your own SQL statements in this file.
(basically same specifications as replace-schema.sql)

The "data" directory is for data loading like this:

  private static class QueuingExecutor implements Executor {
    private final Deque<Runnable> tasks = new ArrayDeque<>();

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

    private void runNext() {
      tasks.removeFirst().run();
    }
  }

  public void testAsyncReload() throws Exception {
    AtomicInteger loadCount = new AtomicInteger();

import java.io.IOException
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.LinkedBlockingDeque
import java.util.concurrent.TimeUnit
import okhttp3.internal.concurrent.Task
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.RoutePlanner.ConnectResult
import okhttp3.internal.connection.RoutePlanner.Plan
import okhttp3.internal.okHttpName

/**

    allTasks.add(setFutureCompleteExceptionallyRunnable);
    allTasks.add(setFutureCancelRunnable);
    for (int k = 0; k < 50; k++) {
      // For each listener we add a task that submits it to the executor directly for the blocking
      // get use case and another task that adds it as a listener to the future to exercise both
      // racing addListener calls and addListener calls completing after the future completes.

/// tip

/// tip | Consejo