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Message-ID: <5607CF32.7030707@yandex.ru>
Date: Sun, 27 Sep 2015 14:12:50 +0300
From: Nikolai Zhubr <n-a-zhubr@yandex.ru>
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Subject: Re: [pgadmin-support] Stability and compatability issues on windows
 xp
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Hi,
27.09.2015 8:20, J.F. Oster wrote:
> Hello,
>
> NZ>  So, is it planned e.g. to publish some beta windows binaries?
>
> +1 for publishing beta binaries.
>
> NZ>  I'm on windows xp sp3 (32-bit).
>
> Windows XP is not supported officially, http://www.pgadmin.org/download/windows.php
>    From v1.16.0, Windows XP/2003 or later is required, and from 1.20.0, Windows Vista/2008 is required.

Indeed, thanks, I've somehow overlooked this one.
And its a real pity (for me at least).

I wouldn't dismiss windows xp here just for that, and I can't imagine 
any real new feature of windows vista that pgadmin needs so much now.

Rather, it is probably that officially preferred version of microsoft 
build tools has dropped support for windows xp target (which is 
certainly logical from microsoft pov) and maintainers might have not 
enough resources and/or motivation to deal with a number of various 
microsoft compilers simultaneously (which is actually logical too).

And this leads to a somewhat ridiculous situation, that I've just easily 
updated postgresql from 9.0 to 9.4 here, all my apps are running fine, 
except that an (important, but still) auxilary productivity utility 
(which saves me lots of typing and is nice, yes) now wants me to change 
an operating system.

On the other hand, AFAIK wxwidgets is _just_ dropping support for win9x 
(!) now, and furthermore, the 2.8 version of wxwidgets used in 
officially released pgadmin 1.20 is somewhat antique (and AFAICS cannot 
be officially obtained other than compiled from source) so I'm not sure 
one could expect any fixes for it even if one needed some.

> But there was a commit related to XP after 1.20 release:
> http://git.postgresql.org/gitweb/?p=pgadmin3.git;a=commit;h=b845880cc1352820b14a1e9af7b56eb3a513a38b
> So probably it is supposed to work :)

Ah, this change was applied after 1.20 release, so yes, despite 
officially not supported, it might happen that a binary valid for 
windows xp will also appear in an upcoming release.

> Building on Windows is somewhat tricky. I can assist but note that I
> build on Windows 7 and have never seen the bug you described.

Ok, thanks. I'd suppose build process on windows should not depend much 
on the build host version.

Some more about the bug itself.
It is triggered easily in the SQL-query panel by just some typing, then 
clicking back and forth between the editor and tabs below, and some 
moving this panel window as a whole. In order to notice the problem 
quickly, I just fire taskmanager before and minimize it so I can see CPU 
load increase immediately.

The bug looks like a (in)famous invalidate-repaint-invalidate dead loop. 
That is: CPU load increases to the max, GUI responsiveness drops, window 
contents gradually become corrupt (not properly repainted), finally the 
window becomes completely dead and can not even be closed by the 'close' 
button. Or sometimes the window might come back to life subsequently, 
depending on how exactly I move and click it. If connected via remote 
desktop, visual artifacts get much more noticable.

Generally such problem (on windows) typically happens when an 
application tries to automatically rearrange window elements as a 
reaction so some GUI event (like e.g. window resize by user) and while 
doing such rearrangement it ocasionally (maybe indirectly) fires some 
other GUI event (of the same or another type), which in turn causes yet 
another rearrangement and so on, sometimes with visible flickering, 
sometimes without. (Seen this plenty.)

Now starting with vista, if I understand it correctly, window 
invalidation and repainting technique has changed somewhat, so, what is 
relevant to the issue in question, less invalidation events are exposed 
to an application (as they are now processed by window manager or 
whatever). While probably a reasonable change, it certainly doesn't drop 
a requirement that repainting must not cause cyclic invalidation. But if 
all of develpoment and testing is performed on windows 7 then it is 
perfectly clear the bug could well stay unnoticed.

I think it would be good to fix it. It might be even not so difficult. I 
could maybe provide remote access to a VM with windows xp if some 
developer is interested.
Besides, I suspect that with some luck the problem might also trigger on 
vista+ when running pgadmin through a remote desktop, although I'm not 
quite sure.


Thank you,
Nikolai


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