Apoapsis increasing by itself - rapidly

[Gordon Dry]

Edit:

ah, I see: http://bugs.kerbalspaceprogram.com/issues/9619

 

RO / RSS / RemoteTech / MJ / Trajectories and more, see log

No thrust, just coasting. No RCS. Only reaction wheels to hold prograde later, the first screenshots show no interaction at all (slightly rotating).

After I circularized an Earth orbit at 800,000 km my apoapsis is increasing rapidly at about more than 100 km a second ... not long and I will achieve Earth escape without doing anything for it ...
It does not happen on timewarp on-rails.

Some screenshots to compare:

Log until now:
https://www.dropbox.com/s/zh1fivqv6p9a9br/2016-06-04-1 Apoapsis increasing by itself - rapidly.7z?dl=0

btw why for heavens sake is the picture order here not the same as setup on imgur itself?
The pictures are ordered wrong, first is last. After a couple of hours they magically appear in the correct order...
And this WYSIWIG editor is bad, difficult to place the album at another spot and trying to it's not where I set it.
Needed several edits to place it.

Edited June 5, 2016 by Gordon Dry

[Gordon Dry]

Hopefully the bug is kinda "unnecessary recalculation of the orbit trajectory" and fixing it will increase game performance by avoiding these extra calculations.
Worst case would be that fixing this would decrease game performance.
... aaand also it would be magic if fixing this also decreases the GC stutter issue...

[Gordon Dry]

Interesting fact, dunno if this was mentioned before.

I just launched a new vessel and later I recognized that the one mentioned in my OP that went Earth eject now was still on rails at 800,000 km like it was after finishing the last maneuver (and before I started doing screenshots).

So internally data-wise everything is correct (and stays correct) but on focus it's going nuts.

[Padishar]

19 hours ago, Gordon Dry said:

.. aaand also it would be magic if fixing this also decreases the GC stutter issue...

It certainly would be magic because the code concerned has nothing whatsoever to do with GC stutter.  The bug is not "unnecessary" anything.  When a vessel is off rails, Unity/PhysX changes its velocity and acceleration constantly and these calculations are not as accurate as the on-rails orbit calculations.  This means that adjustments are required to the off-rails vessel to try to stop the reported orbit changing.  There was always a periodic change to the orbit of off-rails vessels but this didn't result in the specific orbital energy changing (much).  An attempt was made to improve the drifting orbits and, while it did greatly reduce the periodic nature of the drift, it also effectively caused the energy of the orbit to decrease constantly.

Squad have clearly stated that they are looking at this and it should be fixed in 1.1.3 but it has nothing to do with GC stutter and the fix is unlikely to affect the performance in any noticeable way.