[Lazarus] Threads and Libraries (dll and so)

[Mark Morgan Lloyd]

Michael Van Canneyt wrote:

> The GUI is for use by humans. That means that there is no point 
> whatsoever in updating the GUI more than 10 times per second: the human 
> eye cannot process information faster than that, let alone that the 
> brain can grasp the *meaning* of what the eye has seen in such a short 
> time.
> 
> Designating 1 GUI thread to update the entire screen 10 times per second 
> should therefor a) be entirely possible with any GUI widgetset.
> b) be complete overkill for any human operator.

I'm afraid I disagree. As a trivial example, the position of the mouse 
pointer is updated much more often than every 100mSec, not to mention 
things like animated pointers and icons. Just because a GUI invites user 
interaction doesn't mean that it can't run asynchronously.

> if I play a video at full HD, 1 thread handles the screen display. It 
> works just fine,
> and probable needs to transfer a lot more data to the screen than any 
> normal program would have to transfer. It would be very surprising if 
> you would not be able to show some statistical data (or whatever) on 
> screen with the same hardware.

I'm afraid I disagree with that even more, since when you play a video 
you're relying on hardware decompression which you can't reliably 
characterise as either single- or multi-threaded. Believe me, I've got 
Linux etc. on so many odd and ageing systems around here that I 
regularly come up against the suppurating lacerations that were 
"bleeding edge" until some developer lost interest and didn't stitch it 
up, and in my experience the thing that's most likely to work is DVD 
playback because the data stream is (as I understand it) sent via a 
backdoor to the graphics chips bypassing most of the kernel and X.

Having said which, I'm not unreservedly siding with MichaelS's position, 
since unless it completely bypassed any existing widget set (and 
preferably drew directly to the framebuffer) it could be screwed at any 
time by off-project developers (i.e. the Gnome, Qt or Windows teams).

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]