The Java doc of ScheduledExecutorService.scheduleWithFixedDelay describes as the below:
Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next. . Otherwise, the task will only terminate via cancellation or termination of the executor.
So in IoTDB there're some important schedule tasks but without exception protection, which may be the risk of unexcepted non-schedule of them. We should fix it.
Note that WrappedSingleThreadScheduledExecutor and WrappedScheduledExecutorService should be unchanged as they are just the implementations of ScheduledExecutorService and should obey the interface definition.