POV-Ray : Newsgroups : povray.bugreports : Right-click menu in Windows Explorer : Re: Right-click menu in Windows Explorer Server Time
28 Sep 2021 14:52:00 EDT (-0400)
  Re: Right-click menu in Windows Explorer  
From: clipka
Date: 22 Jan 2018 05:47:19
Message: <5a65c137@news.povray.org>
Am 21.01.2018 um 23:40 schrieb Kenneth:
> With v3.7.1 beta 9 (in Win 7), and "keep single instance" active, I'm actually
> getting *both* behaviors, seemingly at random. Sometimes 2 files open 2 copies
> of POV-Ray, sometimes only one copy with the usual "You've decided to keep
> single instance" warning (and then both files are loaded into that single
> instance.) I haven't yet nailed down the reason for this-- perhaps it depends on
> whether or not  one (or both?) of the chosen files have already been loaded
> previously? or maybe/also on which of the 2 files is chosen from the desktop to
> 'Edit with POV-Ray'? I've tried a few tests of those permutations, but I still
> don't get completely consistent results.

From a theoretical point of view, that seemingly random behaviour
actually makes kind of sense: I guess Windows will always run POV-Ray
for each individual file separately, and each instance of POV-Ray will
in turn try to figure out whether it should actually open the file
itself or defer that job to another instance (which I'll refer to as the
"king of the hill").

Now when an instance is started, it presumably first looks around
whether there already is a king of the hill, and only if such a king
isn't there it will declare itself king. This leaves a small time window
in which another instance looking for a king will see none, although one
is already in the process of declaring itself king.

In informatics, such situations are referred to as "race conditions",
and they are a real pain in the ass when trying to properly synchronize
multiple portions of a system (in this case two instances of POV-Ray).

This is probably non-trivial to solve, and given that we want to get rid
of that old POV-Ray for Windows anyway, I doubt whether it would be
worth the time and energy.


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