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Zdravím, v programu používám zatím samé QT widgety nebo třídy z nich odvozené, takže by se o jejich dealokaci mělo QT postarat. Zkusmo jsem to projel Valgrindem a objevil několik memory leaků při volání funkcí přilinkovaných knihoven. Možná, že jsem někde špatně (ne)přiřadil rodiče widgetů, ale radši jsem si napsal jednoduchý program, který má ty samé memory leaky.

mem.h

#include <QWidget>

class Mem : public QWidget
{
	public:
		Mem	(QWidget * parent = NULL);
};

mem.cpp

#include "mem.h"
#include <QVBoxLayout>
#include <QLabel>

	Mem::Mem	(QWidget * parent)
	: QWidget(parent)
{
	QVBoxLayout * vbox = new QVBoxLayout(this);

	QLabel * one = new QLabel("Hello");
	QLabel * two = new QLabel("world!");

	vbox->addWidget(one);
	vbox->addWidget(two);

	setLayout(vbox);
}

main.cpp

#include <QApplication>
#include "mem.h"

int main (int argc, char ** argv)
{
	QApplication app(argc,argv);

	Mem window;
	window.show();

	return app.exec();
}

A teď výpis z Valgrindu:

==26725== HEAP SUMMARY:
==26725==     in use at exit: 83,285 bytes in 1,696 blocks
==26725==   total heap usage: 17,743 allocs, 16,047 frees, 1,890,066 bytes allocated
==26725== 
==26725== LEAK SUMMARY:
==26725==    definitely lost: 192 bytes in 2 blocks
==26725==    indirectly lost: 912 bytes in 34 blocks
==26725==      possibly lost: 1,720 bytes in 9 blocks
==26725==    still reachable: 80,461 bytes in 1,651 blocks
==26725==         suppressed: 0 bytes in 0 blocks

Výpis s --leak-check=full

==27097== Memcheck, a memory error detector
==27097== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==27097== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
==27097== Command: ./memory_leak
==27097== Parent PID: 24134
==27097== 
==27097== 
==27097== HEAP SUMMARY:
==27097==     in use at exit: 83,285 bytes in 1,696 blocks
==27097==   total heap usage: 17,438 allocs, 15,742 frees, 1,884,214 bytes allocated
==27097== 
==27097== 120 bytes in 1 blocks are possibly lost in loss record 116 of 170
==27097==    at 0x4024150: memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x402420E: posix_memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x509FFA9: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A14C8: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A219D: g_slist_prepend (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A516C: g_strsplit (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50BACB8: g_get_language_names (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50BB216: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50AD289: g_thread_init_glib (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50364B5: g_thread_init (in /usr/lib/libgthread-2.0.so.0.2800.6)
==27097==    by 0x4C61941: QEventDispatcherGlibPrivate::QEventDispatcherGlibPrivate(_GMainContext*) (in /usr/lib/qt/lib/libQtCore.so.4.7.0)
==27097==    by 0x4227BB5: ??? (in /usr/lib/qt/lib/libQtGui.so.4.7.0)
==27097== 
==27097== 124 bytes in 1 blocks are definitely lost in loss record 117 of 170
==27097==    at 0x4025BB8: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x53CCE52: ??? (in /usr/lib/libxcb.so.1.1.0)
==27097==    by 0x53CCF54: ??? (in /usr/lib/libxcb.so.1.1.0)
==27097==    by 0x53CC813: xcb_connect_to_display_with_auth_info (in /usr/lib/libxcb.so.1.1.0)
==27097==    by 0x53CCB5B: xcb_connect (in /usr/lib/libxcb.so.1.1.0)
==27097==    by 0x52D5652: _XConnectXCB (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52C5476: XOpenDisplay (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x41FBC5C: ??? (in /usr/lib/qt/lib/libQtGui.so.4.7.0)
==27097==    by 0x417DAD7: QApplicationPrivate::construct(_XDisplay*, unsigned long, unsigned long) (in /usr/lib/qt/lib/libQtGui.so.4.7.0)
==27097==    by 0x417E342: QApplication::QApplication(int&, char**, int) (in /usr/lib/qt/lib/libQtGui.so.4.7.0)
==27097==    by 0x8049E7A: main (in /home/yenn/qt/memory_leak/memory_leak)
==27097== 
==27097== 360 bytes in 3 blocks are possibly lost in loss record 132 of 170
==27097==    at 0x4024150: memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x402420E: posix_memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x509FFA9: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A14E5: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A219D: g_slist_prepend (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A516C: g_strsplit (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50BACB8: g_get_language_names (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50BB216: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50AD289: g_thread_init_glib (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50364B5: g_thread_init (in /usr/lib/libgthread-2.0.so.0.2800.6)
==27097==    by 0x4C61941: QEventDispatcherGlibPrivate::QEventDispatcherGlibPrivate(_GMainContext*) (in /usr/lib/qt/lib/libQtCore.so.4.7.0)
==27097==    by 0x4227BB5: ??? (in /usr/lib/qt/lib/libQtGui.so.4.7.0)
==27097== 
==27097== 980 (68 direct, 912 indirect) bytes in 1 blocks are definitely lost in loss record 150 of 170
==27097==    at 0x4025C9E: realloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x52E9A57: ??? (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52E9FD0: ??? (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52EBC91: ??? (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52EC4B4: _XlcCreateLC (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x530F509: _XlcUtf8Loader (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52F43BB: _XOpenLC (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52F467D: _XrmInitParseInfo (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52DAA10: ??? (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52DE1B7: XrmGetStringDatabase (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52B9ADE: ??? (in /usr/lib/libX11.so.6.3.0)
==27097==    by 0x52B9D0E: XGetDefault (in /usr/lib/libX11.so.6.3.0)
==27097== 
==27097== 1,240 bytes in 5 blocks are possibly lost in loss record 156 of 170
==27097==    at 0x4024150: memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x402420E: posix_memalign (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==27097==    by 0x509FFA9: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50A14E5: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50545F8: g_array_sized_new (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50546D2: g_array_new (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50AD16E: g_static_private_set (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x5064846: g_get_filename_charsets (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50648CC: ??? (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50AD279: g_thread_init_glib (in /usr/lib/libglib-2.0.so.0.2800.6)
==27097==    by 0x50364B5: g_thread_init (in /usr/lib/libgthread-2.0.so.0.2800.6)
==27097==    by 0x4C61941: QEventDispatcherGlibPrivate::QEventDispatcherGlibPrivate(_GMainContext*) (in /usr/lib/qt/lib/libQtCore.so.4.7.0)
==27097== 
==27097== LEAK SUMMARY:
==27097==    definitely lost: 192 bytes in 2 blocks
==27097==    indirectly lost: 912 bytes in 34 blocks
==27097==      possibly lost: 1,720 bytes in 9 blocks
==27097==    still reachable: 80,461 bytes in 1,651 blocks
==27097==         suppressed: 0 bytes in 0 blocks
==27097== Reachable blocks (those to which a pointer was found) are not shown.
==27097== To see them, rerun with: --leak-check=full --show-reachable=yes
==27097== 
==27097== For counts of detected and suppressed errors, rerun with: -v
==27097== ERROR SUMMARY: 5 errors from 5 contexts (suppressed: 75 from 9)

OS: Slackware-current, g++ 4.5.3, QT 4.7

Je to chyba v QT nebo dělám něco špatně já?