/** Lock used whenever accessing the state variables (runningTasks, shutdown) of the executor */
    private final Object lock = new Object();

    /*
     * Conceptually, these two variables describe the executor being in
     * one of three states:
     *   - Active: shutdown == false
     *   - Shutdown: runningTasks > 0 and shutdown == true
     *   - Terminated: runningTasks == 0 and shutdown == true
     */

              runningTask = scheduler().schedule(delegate, executorService, task);
              notifyStarted();
            } catch (Throwable t) {
              restoreInterruptIfIsInterruptedException(t);
              notifyFailed(t);
              if (runningTask != null) {
                // prevent the task from running if possible
                runningTask.cancel(false);
              }