/** Queues with tasks that are currently executing their [TaskQueue.activeTask]. */
  private val busyQueues = mutableListOf<TaskQueue>()

  /** Queues not in [busyQueues] that have non-empty [TaskQueue.futureTasks]. */
  private val readyQueues = mutableListOf<TaskQueue>()

  private val runnable: Runnable =
    object : Runnable {
      override fun run() {
        var task: Task =
          withLock {

  private fun serviceSocketTask(socket: BufferedSocket): FutureTask<Void> {
    return FutureTask<Void> {
      socket.source.use {
        socket.sink.use {
          while (true) {
            val action = actions.poll() ?: break
            action(socket)
          }
        }
      }
      return@FutureTask null
    }
  }

        new Runnable() {
          @Override
          public void run() {
            threadLocalCount.set(threadLocalCount.get() + 1);
          }
        };

    FutureTask<@Nullable Void> otherTask =
        new FutureTask<>(
            () -> {
              Future<?> future = executor.submit(incrementTask);
              assertTrue(future.isDone());

        new Runnable() {
          @Override
          public void run() {
            threadLocalCount.set(threadLocalCount.get() + 1);
          }
        };

    FutureTask<@Nullable Void> otherTask =
        new FutureTask<>(
            () -> {
              Future<?> future = executor.submit(incrementTask);
              assertTrue(future.isDone());

    Runnable runChosenTest =
        new Runnable() {
          @Override
          public void run() {
            runChosenTest();
          }
        };
    FutureTask<@Nullable Void> task = new FutureTask<>(runChosenTest, null);
    startThread(
        new Runnable() {
          @Override
          public void run() {
            task.run();
          }
        });

  //   system scheduling and as such we could either miss our deadline, or unpark() could be delayed
  //   so that it looks like we timed out even though we didn't. For comparison FutureTask respects
  //   completion preferably and AQS is non-deterministic (depends on where in the queue the waiter
  //   is). If we wanted to be strict about it, we could store the unpark() time in the Waiter node

  //   system scheduling and as such we could either miss our deadline, or unpark() could be delayed
  //   so that it looks like we timed out even though we didn't. For comparison FutureTask respects
  //   completion preferably and AQS is non-deterministic (depends on where in the queue the waiter
  //   is). If we wanted to be strict about it, we could store the unpark() time in the Waiter node

         * Future might not even be a ListenableFuture, just a plain Future. That said, similar
         * problems can exist with methods like FutureTask.done(), not to mention slow calls to
         * Thread.interrupt() (as discussed in InterruptibleTask). At the end of the day, it's
         * unlikely that cancel() will be slow, so we can probably get away with calling it while

         * Future might not even be a ListenableFuture, just a plain Future. That said, similar
         * problems can exist with methods like FutureTask.done(), not to mention slow calls to
         * Thread.interrupt() (as discussed in InterruptibleTask). At the end of the day, it's
         * unlikely that cancel() will be slow, so we can probably get away with calling it while