Async timer stall behavior

Question

In service to my unending quest to understand async timers ...
I have an app with two async timers, each with its own callback, and I understand both run on the same thread.
So if one of the callbacks stalls, will the other ever get scheduled?  If they're truly on the same, single thread, then if you lock up one of the two callbacks (e.g. put it into an endless loop), then the other callback should never get called.
Thanks.
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Answer 1

Thanks for the info!
Yes, I had seen behavior over long runs (application runs for weeks at a time, constantly using two async callbacks) that caused me to believe there was some unobvious semantic to the async timer scheduling, which you've just explained.  If this is NI implmentation detail, it's never been explained anywhere that I can find.
I do need to prevent the 30 second callback from taking longer than the timer period - it normally doesn't, and in that case everything works as expected.
I create the 15 second timer first, and that's the one that continues to get callbacks after the 30 sec timer stops getting its.
What I still don't have a grip on, is that if it's the 15 second timer that gets priority, and it has enqueued a bunch of callbacks missed because the 30 second timer was stuck in it's callback, why doesn't the 15 second timer flush out all of it's enqueued callbacks once it's able to?  Otherwise, queueing them up doesn't make sense.  I would have thought that the 15 sec timer would flush it's enqueud callbacks out as fast as they were serviced, and then both timers would resume getting their callbacks per their schedules.
Here's my code:
#define POLL_INTERVAL 15
#define CONTROL_INTERVAL 30
// Create polling and control async timers, start callbacks
   iPollTimer    = NewAsyncTimer (POLL_INTERVAL, -1, 1, MeasurementPoll, 0);
   iControlTimer = NewAsyncTimer (CONTROL_INTERVAL, -1, 1, Control, 0);
Another thought I have is that this is a fast, 8 core PC.  I wonder if there's some weirdness getting in due to the true parallel execution that can take place, though the async timers are on the same thread so shouldn't be a race there.
When the 30 sec timer stops getting callbacks, the 15 sec timer callback interval gets stretched out to about 25 seconds - up until then, I see the expected, regular 15 and 30 sec callbacks.
Thanks again.