toBeGCed = null;
    GcFinalization.awaitClear(ref);
  }

  private static Callable<String> toStringCallable(Object object) {
    return object::toString;
  }

  public void testCancellationDuringReentrancy() throws Exception {
    TestLogHandler logHandler = new TestLogHandler();
    Logger.getLogger(AbstractFuture.class.getName()).addHandler(logHandler);

    List<Future<?>> results = new ArrayList<>();