如何从 ScheduledExecutorService 获取队列和池大小

Question

我正在创建一个调度程序并以 2 秒的延迟安排作业。但在安排特定作业之前，我想检查 ScheduledExecutorService 的池大小和队列大小，但我找不到任何方法。任何人都可以向我建议如何在安排任何作业之前检查 ScheduledExecutorService 的池大小和队列大小。

   //here i have created ScheduledExecutorService 
private static final ScheduledExecutorService SCHEDULED_EXECUTOR_SERVICE;


static {
     //initialized  ScheduledExecutorService with 30 pool size
    Scheduled_Executor_Service = (ThreadPoolExecutor) Executors.newScheduledThreadPool(30);
}


public void addTaskTOSchedule(){

  //Here i want to check poolsize and queue size of SCHEDULED_EXECUTOR_SERVICE if 
  //ScheduledExecutorService already used more then specific number thread then i will not schedule job

SCHEDULED_EXECUTOR_SERVICE.schedule(() -> {
                    User user = new User();
                    SCHEDULED_EXECUTOR_SERVICE.execute(user);
                }, 2000, TimeUnit.MILLISECONDS);
}

Answer 1

ScheduledExecutorService 接口不允许访问内部队列。您必须将服务转换为实现类以获取队列的大小，如下所示：

ScheduledExecutorService Scheduled_Executor_Service = Executors.newScheduledThreadPool(30);
        if (Scheduled_Executor_Service instanceof ScheduledThreadPoolExecutor) {
            ScheduledThreadPoolExecutor implementation = (ScheduledThreadPoolExecutor) Scheduled_Executor_Service;
            int size = implementation.getQueue().size();

        }