[Qt-qml] QML memory usage with "import QtWebKit"

[Gregory Schlomoff]

Thanks guys for those explanations.

Now I understand what is going on

Cheers,

Greg

On Thu, Dec 16, 2010 at 7:25 AM,  <warwick.allison at nokia.com> wrote:
> This is why it depends on exactly which memory you’re measuring – linking in
> a library DOES use memory, because of the way virtual tables work in C++:
> just “knowing about” the type – i.e. the metaobject information, even with
> no instances, means the vtable must be loaded, and that of course has
> references to all the virtual functions (often much of the class), in
> addition to all signals and slots and property accessors in Qt’s metaobject
> info.
>
>
>
> Importing a module means making types available, and that means loading and
> processing. While in theory QML could delay some of that until it comes
> across a type it doesn’t know about yet, that seems a pointless
> optimization.
>
>
>
> So if the memory is mainly read-only shared code pages, there is nothing
> unexpected happening.
>
>
>
> As for documentation, this is internal detail that is not really relevant to
> QML authors, and could in theory change at any time, so not something anyone
> should be relying on one way or another.
>
>
>
> --
>
> Warwick
>
>
>
>
>
> I'm sharing those numbers not because I think they are somehow too high, or
> too low, but because I am surprised to see memory usage *grow by a
> significant amount* even when I'm *not instantiating* anything.
>
>
>
> Put it another way: the fact that a single "import WebKit 1.0" line adds 10
> MB of memory usage, even though I'm NOT instantiating any WebView element is
> an unexpected behaviour to me, and may indicate either a bug with the way
> QML deals with imports, or a normal but unexpected behavior that should be
> explained / documented.
>
>