Issues with Sleep(1) called in a loop

[Yaron 53]

I use a thread to update an animated 'please wait' dialog while doing other things in the background.

 

The issue is, I want to be able to dismiss the please wait dialog instantly and since I use animations, I use "Sleep" commands to to time the animation and take minimum CPU time.

 

However, for some reason, doing Sleep(10) returns a vastly different result than calling For I := 0 to 1 do If Terminated = False then Sleep(5); which for some reasons takes ~30ms to complete.

For reference, calling For I := 0 to 9 do If Terminated = False then Sleep(1); takes ~150ms.

 

My problem is with Delphi 7, but I doubt it's specific to this version of Delphi, any ideas?

Edited April 18, 2021 by Yaron

[Yaron 53]

Nevermind, I replaced Sleep with WaitForSingleObject and used an event to break out of the wait when closing the dialog.

[FPiette 384]

You should not access the UI from a thread.

 

[David Heffernan 2345]

14 hours ago, Yaron said:

any ideas?

Answer can be found in the documentation of Sleep. Sleep can only wait for multiples of system ticks. And your system appears to tick at a frequency of 15ms. Which is typical, that being the default tick frequency. There are many many discussions of this online. Here's one: https://stackoverflow.com/questions/3744032/why-are-net-timers-limited-to-15-ms-resolution

[Remy Lebeau 1400]

And also: https://stackoverflow.com/questions/9518106/winapi-sleep-function-call-sleeps-for-longer-than-expected