[Qt-interest] QFileIconProvider "leaks" DLL's (qgifd4.dll, qicod4.dll, QtSvgd4.dll, etc.)

[Thiago Macieira]

Em Terça-feira 18 Agosto 2009, às 19:20:24, Niels Dekker - no return address 
escreveu:
> QFileIconProvider loads some DLL files that aren't unloaded anymore.
> When I step over the QFileIconProvider constructor in the debugger (MSVC
> 2008), I get the following debug output:
> 
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qgifd4.dll'
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qicod4.dll'
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qjpegd4.dll'
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qmngd4.dll'
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qsvgd4.dll'
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\bin\QtSvgd4.dll', Symbols loaded.
>  'Foo.exe': Loaded 'C:\Qt\4.5.2\plugins\imageformats\qtiffd4.dll'
> 
> Those DLL's remain in memory, and thereby, QtGui4.DLL and QtCore4.dll
> also remain there. Is that a bug? Shouldn't the destructor of
> QFileIconProvider unload those DLL's?  Or should I unload those DLL's
> myself, after using QFileIconProvider, in my own code?  (If so, how
> should I do so?)
> 
> It appears that the DLL's are loaded inside QFileIconProviderPrivate(),
> when it does:
>   trashcan = style->standardIcon(QStyle::SP_TrashIcon);
> (In "C:\Qt\4.5.2\src\gui\itemviews\qfileiconprovider.cpp")

Those are standard Qt plugins. They are loaded by the QImageReader class, when 
trying to parse icon images.

They should get unloaded automatically when QtCore is unloaded.

You're saying that QtGui isn't unloaded because those plugins are still 
loaded. But the plugins only get unloaded when QtCore is unloaded.

So, chicken and the egg problem.

No solution that I can think of.
-- 
Thiago Macieira - thiago.macieira (AT) nokia.com
  Senior Product Manager - Nokia, Qt Development Frameworks
     Sandakerveien 116, NO-0402 Oslo, Norway

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