Why label text doesn't update and clock doesn't trigger until the procedure count ends?

[Martin_Herraiz]

Hi. I made a little app to check a doubt I have.
The doubt is about if a series of procedures calling each other would be "interrupted" by some other event (like the press of a button, or the trigger of a clock).
So my app has a clock triggering every second, and a counter from 0 to 9999.
I read App Inventor is single threaded, so I think I understand why, once I hit the button and start the counter, the clock stops triggering until the count ends. And then the clock starts triggering again.
I expected to see the count in the label increase from 0 to 1, and so on, until 9999.
But, to my surprise all I see when I hit the button, is the clock stops. And then, only when the count ends, the label changes suddently to 9999. (And also the background color of the button only then changes to green).
Is there an explanation for this?

Interrup.aia (3.5 KB)

[ABG]

That's how it works,

Essays on this are at

FAQ Section: Waiting and Timing

Async Procedure extension - kodular How to do something long running - Taifun How to run an accurate metronome Pause and Break in Loops Extension - Juan Antonio Why you can't wait in AI2 Event-Based programming in AI2 - FTurbak CCSCNE14-AI2-events-first-paper.pdf (432.1 KB) How to avoid using delay() in Arduino - JuanAntonio, docs.arduino.cc

[Martin_Herraiz]

Thanks a lot for the links (I didn't know wich were the correct keywords to search for more info).