@Singleton
public class TaskRunner {
    public void doTask () {
        try {
            System.out.println("performs scheduled task");
        } catch (Exception e) {
            logger.error("Error performing task. failed with error: {}", e);
        }
    }
}

@Singleton
public class TaskScheduler {

    private final Runnable runnable;
    private final ScheduledExecutorService executorService;
    private static final Logger logger = LoggerFactory.getLogger(TaskScheduler.class);

    @Inject
    public TaskScheduler(TaskRunner taskRunner, int initialDelay, int period, String timeUnits) {
        this.executorService = Executors.newScheduledThreadPool(1);
        this.runnable = taskRunner::doTask;

        this.scheduledFuture = this.executorService.scheduleAtFixedRate(this.runnable, initialDelay, period,
             TimeUnit.valueOf(timeUnits));
    }

    public static void main(String[] args) {
        TaskRunner taskRunner = new TaskRunner();
        new TaskScheduler(taskRunner);
    }
}

ScheduledThreadPoolExecutor executor = (ScheduledThreadPoolExecutor) schedulerService;
this.queueSize = executor.getQueue().size();
this.remainingCapacity = executor.getQueue().remainingCapacity();
this.terminated = schedulerService.isTerminated();
this.shutdown = schedulerService.isShutdown();
this.taskCount = executor.getTaskCount();
this.activeTaskCount = executor.getActiveCount();
this.completedTaskCount = executor.getCompletedTaskCount();
this.keepAliveTime = executor.getKeepAliveTime(TimeUnit.SECONDS);
this.coreThreadTimeOut = executor.allowsCoreThreadTimeOut();
this.cancelled = scheduledFuture.isCancelled();
this.delay = scheduledFuture.getDelay(TimeUnit.MINUTES);

{
  "queueSize": 1,
  "remainingCapacity": 2147483647,
  "terminated": false,
  "shutdown": false,
  "taskCount": 2,
  "activeTaskCount": 0,
  "completedTaskCount": 1,
  "keepAliveTime": 0,
  "coreThreadTimeOut": false,
  "periodic": true,
  "cancelled": false
}

{
  "queueSize": 0,
  "remainingCapacity": 2147483647,
  "terminated": false,
  "shutdown": false,
  "taskCount": 2,
  "activeTaskCount": 0,
  "completedTaskCount": 2,
  "keepAliveTime": 0,
  "coreThreadTimeOut": false,
  "periodic": true,
  "cancelled": false
}