for (int i = 0; i < 500; i++) {
      System.gc();

      CacheTesting.drainReferenceQueues(cache);
      if (cache.size() == 1) {
        break;
      }
      try {
        Thread.sleep(10);
      } catch (InterruptedException e) {
        /* ignore */
      }
      try {
        // Fill up heap so soft references get cleared.
        filler = new byte[Math.max(filler.length, filler.length * 2)];

    while (!isThreadBlockedOnInstanceOf(t, blocker)) {
      if (t.getState() == Thread.State.TERMINATED) {
        throw new RuntimeException("Thread " + t + " exited unexpectedly");
      }
      Thread.sleep(1);
    }
  }

  private static boolean isThreadBlockedOnInstanceOf(Thread t, Class<?> blocker) {
    return t.getState() == Thread.State.WAITING && blocker.isInstance(LockSupport.getBlocker(t));
  }

      this.everyMillis = everyMillis;
      this.interruptee = interruptee;
    }

    @Override
    public void run() {
      while (true) {
        try {
          Thread.sleep(everyMillis);
        } catch (InterruptedException e) {
          // ok. just stop sleeping.
        }
        if (shouldStop) {
          break;
        }
        interruptee.interrupt();
      }
    }

          public void run() {
            taskDone = true;
          }
        };
    ScheduledFuture<?> future =
        TestingExecutors.noOpScheduledExecutor().schedule(task, 10, TimeUnit.MILLISECONDS);
    Thread.sleep(20);
    assertFalse(taskDone);
    assertFalse(future.isDone());
  }

  public void testNoOpScheduledExecutorShutdown() {
    ListeningScheduledExecutorService executor = TestingExecutors.noOpScheduledExecutor();