[Interest] Is here memory leaks?

[Thiago Macieira]

On Thursday 08 October 2015 21:57:09 Igor Mironchik wrote:
> Hi guys,
> 
> Can anybody explain me, please. Is here memory leaks or no?
> 
> Please look in the attachment...

Yes, these look like real leaks:

==3533== 136 (16 direct, 120 indirect) bytes in 1 blocks are definitely lost in 
loss record 396 of 514
==3533==    at 0x4C2C100: operator new(unsigned long) (in 
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3533==    by 0x5EDF731: QQmlFileSelectorPrivate::QQmlFileSelectorPrivate() 
(in /home/igor/Qt/5.5/gcc_64/lib/libQt5Qml.so.5.5.0)
==3533==    by 0x5EDF949: QQmlFileSelector::QQmlFileSelector(QQmlEngine*, 
QObject*) (in /home/igor/Qt/5.5/gcc_64/lib/libQt5Qml.so.5.5.0)
==3533==    by 0x5ED8C26: QQmlApplicationEnginePrivate::init() (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Qml.so.5.5.0)
==3533==    by 0x40272C: Application::Application(int, char**) 
(application.cpp:15)
==3533==    by 0x402658: main (main.cpp:11)

==3533== 152 (112 direct, 40 indirect) bytes in 1 blocks are definitely lost in 
loss record 400 of 514
==3533==    at 0x4C2C100: operator new(unsigned long) (in 
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3533==    by 0x650EF21: QObject::QObject(QObject*) (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Core.so.5.5.0)
==3533==    by 0x4F74A73: ??? (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)
==3533==    by 0x4F8340C: QSGRenderContext::initialize(QOpenGLContext*) (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)

==3533== 224 (72 direct, 152 indirect) bytes in 1 blocks are definitely lost in 
loss record 414 of 514
==3533==    at 0x4C2C100: operator new(unsigned long) (in 
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3533==    by 0x4F7536B: ??? (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)
==3533==    by 0x4F8364B: QSGRenderContext::createTexture(QImage const&) const 
(in /home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)
==3533==    by 0x4F2DF5B: ??? (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)
==3533==    by 0x4F8554B: 
QSGRenderContext::textureForFactory(QQuickTextureFactory*, QQuickWindow*) (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Quick.so.5.5.0)

The backtrace of the first one goes all the way back to your Application 
constructor (which is missing the & for argc!!), so the leak might be in your 
code, not in Qt.

I'm assuming that all ??? that your log shows are not Qt frames and not of 
Qt's fault. In most cases, I'm probably right. There are some that I'd like 
more information on, like:

==3533== 42 bytes in 1 blocks are definitely lost in loss record 212 of 514
==3533==    at 0x4C2BBA0: malloc (in /usr/lib/valgrind/vgpreload_memcheck-
amd64-linux.so)
==3533==    by 0x142E5F6E: ???
==3533==    by 0x142C9314: ???
==3533==    by 0xEA7D163: ???
==3533==    by 0xEA7D518: ???
==3533==    by 0xDCBAF59: ???
==3533==    by 0xDCB1D11: ???
==3533==    by 0xDC3D0DD: ???
==3533==    by 0x54D46D6: QAccessible::setRootObject(QObject*) (in 
/home/igor/Qt/5.5/gcc_64/lib/libQt5Gui.so.5.5.0)

Please recompile in debug mode and set the XCB plugin to no-unload (add to the 
linker flags: -Wl,-z,nodelete).
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center