Hi Gunnar,
I am sorry if I appear to be unconvincable but I still don't get it.
You suggested disposing toplevel objects manually which I do (see my code
below). Yet there is a noticeable memory leak left.
I created a couple of dump files of the heap using jconsole and had a look at
those using jhat. My findings are that there are many instances of (ordered by
count)
-
com.trolltech.qt.internal.QSignalEmitterInternal$AbstractSignalInternal$Connection
- com.trolltech.qt.QSignalEmitter$Signal1
- com.trolltech.qt.QSignalEmitter$Signal0
- com.trolltech.qt.gui.QHBoxLayout
- com.trolltech.qt.gui.QPushButton
- QtLeak
Most interestingly the "Instance Counts" (jhat) are much less than the number
of instances that I created when pushing the "create button". Still their
number increases when I hit that button a couple of times more. So it seems
that some toplevel QtLeak objects do get disposed while others don't. How can
that be?
I ran my sample on Java 1.6.0_06 with qtjambi-win32-gpl-4.4.0_01 under Windows
XP.
Kind regards, Curt
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QHBoxLayout;
import com.trolltech.qt.gui.QLayout;
import com.trolltech.qt.gui.QPushButton;
import com.trolltech.qt.gui.QWidget;
public class QtLeak extends QWidget{
public static void main(String[] args) {
QApplication.initialize(args);
QtLeak testQtLeak = new QtLeak(null);
testQtLeak.show();
QApplication.exec();
}
public QtLeak(QWidget parent){
super(parent);
QLayout layout = new QHBoxLayout(this);
QPushButton buttonCreate = new QPushButton("Create", this);
buttonCreate.clicked.connect(this, "create()");
layout.addWidget(buttonCreate);
this.setLayout(layout);
}
@SuppressWarnings("unused")
private void create()
{
for(int i=0; i<1000; i++){
QtLeak leak = new QtLeak(null);
leak.dispose();
}
}
}
________________________________
Von: Gunnar Sletta [mailto:[EMAIL PROTECTED]
Gesendet: Fr 28.11.2008 10:41
An: Curt Nowak
Cc: [email protected]
Betreff: Re: AW: [Qt-jambi-interest] Memory Leaks - any updates?
<snip>
The problem is still the same though, just with a few levels of
indirection.
When you do
button.clicked.connect(this, "create()");
you create a reference from the signal to back to the toplevel and you
have a circular reference that is inpenetrable for the garbage collector.
This is in fact a huge problem, and hopefully we can minimize some of
the impact using weak java references in connections, but that will
introduce regressions in cases where references to the target objects
are not being kept.
Given this happens with all connections, it seems that one must
explicitly dispose all toplevels.
best regards,
Gunnar
_______________________________________________
Qt-jambi-interest mailing list
[email protected]
http://lists.trolltech.com/mailman/listinfo/qt-jambi-interest
