I have memory leak on every Qt3/4 application, Qt bug?

Hello, I experience problem,:
When I create project from Kdevelop template(for example KDE "Hello world") and run untouched program with valgrind I get leaks!

I use Kdevlop 3.5.0.1 (2007-October-24 - Third binary snapshot of the stable KDevelop 3.5.x release series) on Kubuntu 7.10


code is untouched after generated with new project template

main.cpp

Code:

---

#include "kdesimpleapp.h"
#include <kapplication.h>
#include <kaboutdata.h>
#include <kcmdlineargs.h>
#include <klocale.h>
 
static const char description[] =
    I18N_NOOP("A KDE KPart Application");
 
static const char version[] = "0.1";
 
static KCmdLineOptions options[] =
{
//    { "+[URL]", I18N_NOOP( "Document to open" ), 0 },
    KCmdLineLastOption
};
 
int main(int argc, char **argv)
{
    KAboutData about("kdesimpleapp", I18N_NOOP("KDEsimpleapp"), version, description,
		     KAboutData::License_GPL, "(C) 2007 unknown,,,", 0, 0, "unknown@unknown");
    about.addAuthor( "unknown,,,", 0, "unknown@unknown" );
    KCmdLineArgs::init(argc, argv, &about);
    KCmdLineArgs::addCmdLineOptions( options );
    KApplication app;
    KDEsimpleapp *mainWin = 0;
 
    if (app.isRestored())
    {
        RESTORE(KDEsimpleapp);
    }
    else
    {
        // no session.. just start up normally
        KCmdLineArgs *args = KCmdLineArgs::parsedArgs();
 
        /// @todo do something with the command line args here
 
        mainWin = new KDEsimpleapp();
        app.setMainWidget( mainWin );
        mainWin->show();
 
        args->clear();
    }
 
    // mainWin has WDestructiveClose flag by default, so it will delete itself.
    return app.exec();
}

---

kdesimpleapp.cpp

Code:

---

#include "kdesimpleapp.h"
 
#include <qlabel.h>
 
#include <kmainwindow.h>
#include <klocale.h>
 
KDEsimpleapp::KDEsimpleapp()
    : KMainWindow( 0, "KDEsimpleapp" )
{
    // set the shell's ui resource file
    setXMLFile("kdesimpleappui.rc");
 
    new QLabel( "Hello World", this, "hello label" );
}
 
KDEsimpleapp::~KDEsimpleapp()
{
}
 
#include "kdesimpleapp.moc"

---

kdesimpleapp.h

Code:

---

#ifndef _KDESIMPLEAPP_H_
#define _KDESIMPLEAPP_H_
 
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
 
#include <kmainwindow.h>
 
/**
 * @short Application Main Window
 * @author unknown,,, <unknown@unknown>
 * @version 0.1
 */
class KDEsimpleapp : public KMainWindow
{
    Q_OBJECT
public:
    /**
     * Default Constructor
     */
    KDEsimpleapp();
 
    /**
     * Default Destructor
     */
    virtual ~KDEsimpleapp();
};
 
#endif // _KDESIMPLEAPP_H_

---

part of my valgrind output:

Code:

---

==23225== ERROR SUMMARY: 25 errors from 12 contexts (suppressed: 97 from 1)
==23225== malloc/free: in use at exit: 190,786 bytes in 2,530 blocks.
==23225== malloc/free: 137,830 allocs, 135,300 frees, 5,833,593 bytes allocated.
==23225== For counts of detected errors, rerun with: -v
==23225== searching for pointers to 2,530 not-freed blocks.
==23225== checked 1,115,428 bytes.
==23225==
==23225==
==23225== 38 bytes in 2 blocks are definitely lost in loss record 71 of 149
==23225==    at 0x4022765: malloc (vg_replace_malloc.c:149)
==23225==    by 0x4F848A7: FcStrCopy (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87DEC: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x538E3D5: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x538F05C: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x539005D: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x5390FA4: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x538878A: XML_ParseBuffer (in /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x4F86F0B: FcConfigParseAndLoad (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87205: FcConfigParseAndLoad (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87307: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87771: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==
==23225==
==23225== 156 (36 direct, 120 indirect) bytes in 1 blocks are definitely lost in loss record 89 of 149
==23225==    at 0x4022765: malloc (vg_replace_malloc.c:149)
==23225==    by 0x531A9B2: (within /lib/tls/i686/cmov/libc-2.6.1.so)
==23225==    by 0x531B208: __nss_database_lookup (in /lib/tls/i686/cmov/libc-2.6.1.so)
==23225==    by 0x5855FDB: ???
==23225==    by 0x585711C: ???
==23225==    by 0x52C7EEB: getpwuid_r (in /lib/tls/i686/cmov/libc-2.6.1.so)
==23225==    by 0x52C789D: getpwuid (in /lib/tls/i686/cmov/libc-2.6.1.so)
==23225==    by 0x448853A: KStandardDirs::addCustomized(KConfig*) (in /usr/lib/libkdecore.so.4.2.0)
==23225==    by 0x448E59C: KConfig::KConfig(QString const&, bool, bool, char const*) (in /usr/lib/libkdecore.so.4.2.0)
==23225==    by 0x448EBBF: KSharedConfig::KSharedConfig(QString const&, bool, bool) (in /usr/lib/libkdecore.so.4.2.0)
==23225==    by 0x448EDC0: KSharedConfig::openConfig(QString const&, bool, bool) (in /usr/lib/libkdecore.so.4.2.0)
==23225==    by 0x448F14D: KInstance::config() const (in /usr/lib/libkdecore.so.4.2.0)
==23225==
==23225==
==23225== 316 (256 direct, 60 indirect) bytes in 2 blocks are definitely lost in loss record 109 of 149
==23225==    at 0x4022765: malloc (vg_replace_malloc.c:149)
==23225==    by 0x4F82363: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F82C63: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F82D67: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87CD0: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x538E3D5: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x538F05C: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x539005D: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x5390FA4: (within /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x538878A: XML_ParseBuffer (in /usr/lib/libexpat.so.1.0.0)
==23225==    by 0x4F86F0B: FcConfigParseAndLoad (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F87205: FcConfigParseAndLoad (in /usr/lib/libfontconfig.so.1.2.0)
==23225==
==23225==
==23225== 2,224 (768 direct, 1,456 indirect) bytes in 2 blocks are definitely lost in loss record 138 of 149
==23225==    at 0x4022862: realloc (vg_replace_malloc.c:306)
==23225==    by 0x4F822A3: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F82C63: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F8315B: (within /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F7FA0F: FcFontRenderPrepare (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F7FBF7: FcFontSetMatch (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4F7FDA9: FcFontMatch (in /usr/lib/libfontconfig.so.1.2.0)
==23225==    by 0x4EF2A3F: XftFontMatch (in /usr/lib/libXft.so.2.1.2)
==23225==    by 0x492B66B: (within /usr/lib/libqt-mt.so.3.3.7)
==23225==    by 0x4930E7C: QFontDatabase::findFont(QFont::Script, QFontPrivate const*, QFontDef const&, int) (in /usr/lib/libqt-mt.so.3.3.7)
==23225==    by 0x48AC988: QFontPrivate::load(QFont::Script) (in /usr/lib/libqt-mt.so.3.3.7)
==23225==    by 0xso.3.3.7)
==23225==
==23225== LEAK SUMMARY:
==23225==    definitely lost: 1,098 bytes in 7 blocks.
==23225==    indirectly lost: 1,636 bytes in 85 blocks.
==23225==      possibly lost: 0 bytes in 0 blocks.
==23225==    still reachable: 188,052 bytes in 2,438 blocks.
==23225==         suppressed: 0 bytes in 0 blocks.
==23225== Reachable blocks (those to which a pointer was found) are not shown.
==23225== To see them, rerun with: --leak-check=full --show-reachable=yes

---

None of the leaks are caused by Qt but for example by fontconfig.

few leaks are related to libqt-mt:

Code:

---

#
==23225==    by 0x4930E7C: QFontDatabase::findFont(QFont::Script, QFontPrivate const*, QFontDef const&, int) (in /usr/lib/libqt-mt.so.3.3.7)
#
==23225==    by 0x48AC988: QFontPrivate::load(QFont::Script) (in /usr/lib/libqt-mt.so.3.3.7)

---

but I noticed other strange thing:
I checked some KDE apps, and every app I checked have small leaks(form various fonts libraries, X11 libraries, KDE libraries, is it normal to linux or it's KDE/Qt related problem? (i used windows before)

Quote:

---

Originally Posted by saugumas

few leaks are related to libqt-mt:

---

No, they are not. If you make a function that leaks memory and I call your function, the leak is in your function, not mine. Look that fontconfig is being called from the function you quote. I'm sure Qt has no memory leaks - Qt devs are very cautious about it.

Quote:

---

I checked some KDE apps, and every app I checked have small leaks(form various fonts libraries, X11 libraries, KDE libraries, is it normal to linux or it's KDE/Qt related problem? (i used windows before)

---

Dependencies' devs don't tend to be as cautious about memory leaks as Qt devs. Qt has nothing to do with it. How is it in KDE, I don't know.