Geoff Reidy writes:
> The major problem I have with fgfs is that I seem to hit a race
> condition where all graphics and sound stop for extended periods of time
> (up to about 30 secs), long enough for autopilot (or me!) to lose
> control and the plane will always crash.
> During this time there is no disk access happening or lack of memory,
> fgfs still uses 99% CPU.
> Doesn't make any difference whether I use the Mesa files or not. Tried
> compiling with/without random-objects and threading.
> Tried running with textures disabled, 16 or 24 bit.
> 
> It happens after covering a certain amount of terrain. It doesn't matter
> if I'm flying the A4 or a Cessna I will go down about 1000km north of
> Sydney, give or take a couple of hundred.
> Over other parts of the world I usually get further but it always gets
> me in the end. The program itself never crashes.
> 
> It's been happening since before version 8.0 came out but noone else
> seems to have the problem? I had put it down to some gcc3.2 weirdness
> but others are using it now.
> 
> I can sometimes precipitate it by switching to tower view, will get a
> white screen, elevation goes to 40000 ft or so, sound stops, oh-oh.

This most likely relates to freeing tile memory (i.e. moving old tiles
out of the cache and reclaiming their memory.)  This was never a fast
process and could result in frame rate glitches.  When David added
random ground cover objects, the problem got *really* bad because the
scene graph structure of a tile got a lot larger.  David and I worked
really hard to optimize that, and I further worked on a partial tile
free-er so we could spread the load out over multiple frames.  This
should have been all fixed by version 0.8.0 so that you should see
very little frame rate impact when you cross a tile boundary.  What
version of flightgear are you running?

Regards,

Curt.
-- 
Curtis Olson   IVLab / HumanFIRST Program       FlightGear Project
Twin Cities    [EMAIL PROTECTED]                  [EMAIL PROTECTED]
Minnesota      http://www.menet.umn.edu/~curt   http://www.flightgear.org

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