QML Loader leaks memory

[chiragbprajapati]

Hi,

Yes exactly, Loader is not releasing memory when i specify source as null. but if now i assign new qml file (other than before assigned) it will allot memory from previously unfreed memory if possible. you can check by simply making Loader element which simply loads two different file which just contains lots of rectangles.

[altera_2011]

Have you been able to resolve this? I'm running into this exact same thing.

[aabc]

How serious is that memory leak ?

[njeisecke]

I've made similar observations. I suspect it's memory fragmentation.

[altera_2011]

Our leak is very serious, on a fully loaded QML (images and stuff) it leaks about 1MB per load. Which is really bad considering we have about 128MB total memory on the Windows CE device we use. We have to reboot the Windows CE device way to often. (several times a day, TPHB is not really happy about that, nor am I).

[chiragbprajapati]

Hi altera,

I havent sort out this problem but rather to reduce start up delay leakage in my application i have loaded files only once and afterwards setting visible to true/false so finally i am not unloading file.

[altera_2011]

Yes, that is what I tried as well but sadly due to the memory constraints that pushed us up right to the maximum. Which caused more out of memory errors.

[aabc]

Are you sure the memory leaks are not because you forgot to free memory you allocated on the heap ?

[altera_2011]

No I'm 100% sure on top of that I've recreated the leak using 2 empty QMLs

https://bugreports.qt-project.org/browse/QTBUG-26032?focusedCommentId=179280#comment-179280

[altera_2011]

One thing that I did notice is that when I add

@m_View->engine()->clearComponentCache();@

The leak is 10 times worse!

[sierdzio]

This is all rather scary. Happens for me, too - due to big JPGs/PNGs loaded, it adds +40MB per unload.

[aabc]

Does it happen only on Qt 4.7.4 or also on Qt 4.7.3 Qt 4.8 and Qt 5 ?

[altera_2011]

4.7.4 + 4.8.2 I have not tested 5 since we require Windows CE support.

[sierdzio]

In my case:

4.7.4, 4.8.1 - QtQuick 1.
Qt5.0.0 - QtQuick 2.

[aabc]

I also saw it on embedded linux.
Its a very serious leak.
It happens all the time there is a loading of new qml pages

[aabc]

We found that the reason for the memory leak is Qt's function:

QDeclarativeEngine::clearComponentCache()

[andre]

Please report a bug in the bug tracker then. Not many Qt Developers (those building Qt itself, not so much those using it) read these forums.

[aabc]

Can you please send me a link ?

[andre]

The "bugtracker":https://bugreports.qt-project.org we usually call "Jira" (after the name of the system it is using). If you report a bug, please:

Put a link to this forum topic in the bugreport, and

Put a link to the bugreport in this forum topic.

[antonio]

somebody has resolved this issue?