// stop it.
    blockingCallable.waitForStart();

    // This time, cancel the future for the first task. The task remains running, only the future
    // is cancelled.
    future1.cancel(false);

    // Give the second task a chance to (incorrectly) start up while the first task is running.
    // (This is the assertion that fails.)

    // stop it.
    blockingCallable.waitForStart();

    // This time, cancel the future for the first task. The task remains running, only the future
    // is cancelled.
    future1.cancel(false);

    // Give the second task a chance to (incorrectly) start up while the first task is running.
    // (This is the assertion that fails.)

    } finally {
      Thread.interrupted();
    }
  }

  public void testGetUnchecked_cancelled() {
    SettableFuture<String> future = SettableFuture.create();
    future.cancel(true);
    try {
      getUnchecked(future);
      fail();
    } catch (CancellationException expected) {
    }
  }

  public void testGetUnchecked_ExecutionExceptionChecked() {
    try {

    future = service.schedule(runnable, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());
    delegateFuture = (ScheduledFuture<?>) delegateQueue.element();
    assertTrue(delegateFuture.isCancelled());

    delegateQueue.clear();

    future = service.scheduleAtFixedRate(runnable, 5, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());

            resultBuf.append(e.getMessage()).append("\n");
        } finally {
            if (timeoutTask != null && !timeoutTask.isCanceled()) {
                timeoutTask.cancel();
            }
        }

        return resultBuf.toString();

    }

    protected void executePython() {
        final List<String> cmdList = new ArrayList<>();

            assertFalse(called);
            assertThat(t).isInstanceOf(CancellationException.class);
            called = true;
          }
        };
    addCallback(f, callback, directExecutor());
    f.cancel(true);
  }

  public void testThrowErrorFromGet() {
    Error error = new AssertionError("ASSERT!");
    ListenableFuture<String> f = UncheckedThrowingFuture.throwingError(error);

            logger.error("ThumbnailGenerator does not work correctly.", t);
            exitCode = Constants.EXIT_FAIL;
        } finally {
            if (systemMonitorTask != null) {
                systemMonitorTask.cancel();
            }
            destroyContainer();
        }

        System.exit(exitCode);
    }

    private static void destroyContainer() {
        TimeoutManager.getInstance().stop();

    return future;
  }

  /*
   * In certain circumstances, this field might theoretically not be visible to an afterDone() call
   * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
   */
  @CheckForNull @LazyInit ListenableFuture<? extends V> inputFuture;
  @CheckForNull @LazyInit Class<X> exceptionType;
  @CheckForNull @LazyInit F fallback;

   * write.
   *
   * 2. visibility of the writes to an afterDone() call triggered by cancel():
   *
   * Since these fields are non-final that means that TimeoutFuture is not being 'safely published',
   * thus a motivated caller may be able to expose the reference to another thread that would then
   * call cancel() and be unable to cancel the delegate.

    public final void addListener(Runnable listener, Executor executor) {
      super.addListener(listener, executor);
    }

    @CanIgnoreReturnValue
    @Override
    public final boolean cancel(boolean mayInterruptIfRunning) {
      return super.cancel(mayInterruptIfRunning);
    }
  }

  private static final Logger log = Logger.getLogger(AbstractFuture.class.getName());

  private State state;
  private V value;