Scheduler - Time Based Tasks and Compensating for Lag

Does anyone have a good idea for a way to compensate for resource lag which causes ticks to be slower?

For instance, if I determine a task should run at 7:15 and at 7:00 I schedule it to run in 18,000 ticks (15mins * 60secs * 20ticks) but then the server lags and ticks happen at less than 20/second during that 15 minute period, the task will run later than 7:15.

Here is an example of such where the task ended up running at 7:24, which is 9 mins late:

I figure I might be able to do something where a task runs every 20 ticks and checks if something is due to run, but that just seems excessive. Is there a smarter way I'm overlooking?

 

This MIGHT work, but it could freeze/crash your server.

Code:text

 
...
Thread t = new Thread(new DelayedThing);
t.start();
 

Code:java

 
public class DelayedThing extends Thread
{
   public void run()
   {
      try
      {
         sleep(1000);//1000 milliseconds, so 1000*seconds for more configurability
      }
      catch(InterruptedException ie({}
      //do something
      @SuppressWarnings("deprecation")
      stop();//stop this thread, to prevent it from running again/or to save system resources
   }  
}