Re: Excessive events

[David Ross <david netwebconsultants com>]

On Thu, 2005-03-17 at 23:53, Lars Clausen wrote:
> On Thu, 2005-03-17 at 14:06 -0500, Larry Dennison wrote:
> > Hello,
> >
> > I did notice something the other night.  I was working on Dia remotely - 
> > xterm'd at home via a VPN connection to work.  When I fired up Dia, I get a 
> > lot of network traffic on the VPN monitor, even though I'm not doing 
> > anything in Dia.  Response was very sluggish.
> >
> > I had seen this before when working on another GTK application.  I had been 
> > writing directing to a window, instead of using a backing store.  GTK 
> > seemed to be stuck in this cycle of "you drew to it, now you need to draw 
> > it again".  When I used a backing store, the problem went away.
>
> I have managed to run Dia over remote X across the atlantic.  Not
> pleasant, but it worked.  Dia itself only updates at some tenths of
> seconds frequency, but we can't do much for GTK.  Why it would be doing
> stuff when nothing's going on I don't grok.
Hi,

This is just a SWAG (sophisticated wild-aXX guess). Its an interesting
problem. I wish I had the time to check it out myself. Here's a story
that (IMHO) provides a plausible explanation.

The pattern described seems similar to a MVC (model view controller)
interface. GTK is supporting views (windows) for multiple applications
(models). A change event in one triggers update messages in all/others
to construct a consistent image. The backing store is a display server
cache allowing a bitmap merge with just the delta(s) transmitted from
the application server.

Using the backing store was a great idea. I remember discussions of
protocol changes, 10 or more years ago, because X traffic was sucking up
LAN bandwidth. Its been so long that if you hadn't included that
information I would have been clueless (fer sur :-) ).

________________________________________________________________________
david

email:    david netwebconsultants com
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