[Vm-dev] Too many full GCs in Cog/Spur ... while just drawing GUI ...

[Eliot Miranda]

_,,,^..^,,,_ (phone)

> On Apr 7, 2016, at 4:04 AM, marcel.taeumel <Marcel.Taeumel at hpi.de> wrote:
> 
> 
> Hi, there!
> 
> Bert and I discovered a maybe problematic behavior of the Spur-GC. In 4.6
> and before, there was never a full GC when calling "ActiveWorld imageForm"
> (as an extreme re-drawing benchmark) in an endless loop.
> 
> See this picture as an example: 
> <http://forum.world.st/file/n4888823/squeak-spur-gc-problem.png> 
> 
> While the user may not notice that behavior for graphical updates, it is
> annoying for sound glitches. In my system with a 120 ms buffer in
> SoundPlayer, full GCs took 160 ms on average. And there were sound glitches.
> 
> There is something going on here with the new GC in Cog/Spur. Just take this
> re-drawing example/benchmark as an indication for a configuration issue wrt.
> today's image sizes, memory sizes, CPU speeds, etc.
> 
> I just want that my sound has no glitches while resizing a system window.
> (Note that putting the sound player at a higher priority than the WeakArray
> finalizer does not help.)

from http://www.mirandabanda.org/cogblog/cog-projects/

"Spur is released as Squeak 5.0, Newspeak and Pharo 5, and 64-bit Squeak 5.0 is in use, but green.  There are still important missing components:
– an incremental global mark-sweep-compact collector that avoids long pause times running a stop-the-world scan-mark-compact during interactive use.

– an improved per-segment compaction algorithm to replace the second cut compaction algorithm (pig compact) that is slow and reorders objects."

Volunteers welcome...

> Best,
> Marcel
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