Details of how Timers work?

Legacy Open AT
3

I think the big question is: what happens if the handler takes so long that the same timer expires again before the handler has finished…

Start Periodic Timer
  |
  | timer 
  | running
  |
  +--expires--> Enter Handler
  |              |
  | timer        |handler
  | running      |running
  |              |for
  +--expires-->  |a          <<*** WHAT HAPPENS HERE??
  |              |long
  |              |time

See: BUG: In the ongoing saga of timers, our hero boldly codes