[webkit-help] How to clear memory held by QtWebkit?

[Konstantin Tokarev]

13.12.2016, 19:35, "Bono Damodi" <probablynotthebestone at gmail.com>:
> Hello,
> is there a way to deinitialise QtWebkit in runtime completely? For example for this code:
>
> #include <QApplication>
> #include <QGraphicsWebView>
> #include <QUrl>
> #include <QTimer>
>
> QGraphicsWebView* graphicsWebView;
>
> class Deleter : public QObject
> {
>     Q_OBJECT
> public slots:
>     void deleteWebView()
>     {
>         delete graphicsWebView;
>     }
> };
>
> int main(int argc, char *argv[])
> {
>     QApplication app(argc, argv);
>     graphicsWebView = new QGraphicsWebView;
>     graphicsWebView->setUrl(QUrl("http://www.google.com"));
>     Deleter d;
>     QTimer::singleShot(10000, &d, SLOT(deleteWebView()));
>     return app.exec();
> }
>
> #include "main.moc"
>
> After deleting graphicsWebView object there is still used about 2mb of physical memory (more than 6 mb of virtual memory) by Webkit's OSAllocator (I tracked mmap's calls by OSAllocator and then correlated with /proc/pid/smaps). Much of the memory seems to be requested by JSC::JIT::compile function.
>
> Is there some way to completely clean QtWebkit after it was initialised?

To clear code compiled by JIT it should be enough to QWebSettings::clearMemoryCaches()

However, note that it's not ever possible to clear 100% of memory allocated by WebKit (any port), because a lot of data structures are by design NeverDestroyed (look for DEFINE_STATIC_LOCAL in your QtWebKit version).

>
> This is Qt 4.8

Please consider upgrading to Qt 5. Qt 4.8 have reached EOL, and all compatible QtWebKit versions are horribly out of date.

>
> Best regards
> ,
>
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-- 
Regards,
Konstantin