我使用QIcon（Qt 4.8.1和MSVC 2008）面临一些内存泄漏。 这种情况发生在简单的QAction（如菜单条目，甚至是由Qt Designer自动生成的条目）或容器项（如QTreeWidgetItem）。 例如：
QTreeWidgetItem *newItem = new QTreeWidgetItem();
newItem->setText(0, "Item");
// This causes a memory leak!
newItem->setIcon(0, QIcon("D:\\Dnl\\QtSandBoxApp\\Resources\\dataset2.png"));
treeWidget->addTopLevelItem(newItem);
经过大量的调试后，我发现QIcon内部使用的是QImage，它似乎被正确销毁（参考计数器降至零）。 我可以生成的最简单的例子如下：
#include "stdafx.h"
#include <QtGui/QApplication>
#include <crtdbg.h>
int main(int argc, char *argv[])
{
_CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
QApplication a(argc, argv);
//QPixmapCache::setCacheLimit(0);
// MEMORY LEAK!
// Internally uses QImageReader
QImage image("D:\\Dnl\\QtSandBoxApp\\Resources\\dataset2.png");
// NO MEMORY LEAK!
//QImage image(QSize(16, 16), QImage::Format_ARGB32);
return 0;
}
我错过了什么吗？ 这是一个非常烦人的问题，因为它会阻止正确的内存泄漏跟踪（即由应用程序引起，而不是由Qt引起）。
编辑：这是内存泄漏报告
Detected memory leaks!
Dumping objects ->
{5637} normal block at 0x00A46020, 76 bytes long.
Data: <d ,g ^ L Bg> 64 D2 2C 67 E8 5E A4 00 00 00 00 00 4C B9 42 67
{5636} normal block at 0x00A45EE8, 12 bytes long.
Data: < z ` z > 14 7A D3 00 20 60 A4 00 00 7A D3 00
{5634} normal block at 0x00A46148, 128 bytes long.
Data: < 6 6 Za > 01 00 00 00 36 00 00 00 36 00 00 00 5A 61 A4 00
{5614} normal block at 0x00A45DC8, 76 bytes long.
Data: <d ,g x L Bg> 64 D2 2C 67 E8 78 A4 00 00 00 00 00 4C B9 42 67
{5613} normal block at 0x00A478E8, 12 bytes long.
Data: < ] > A4 96 CA 00 C8 5D A4 00 90 96 CA 00
{5611} normal block at 0x00A45C48, 128 bytes long.
Data: < 6 5 Z\ > 01 00 00 00 36 00 00 00 35 00 00 00 5A 5C A4 00
{5591} normal block at 0x00A477C8, 76 bytes long.
Data: <d ,g u L Bg> 64 D2 2C 67 10 75 A4 00 00 00 00 00 4C B9 42 67
{5590} normal block at 0x00A47510, 12 bytes long.
Data: < w > B8 96 C6 00 C8 77 A4 00 A4 96 C6 00
{5588} normal block at 0x00A45B88, 128 bytes long.
Data: < 6 5 [ > 01 00 00 00 36 00 00 00 35 00 00 00 9A 5B A4 00
{5566} normal block at 0x00A473F0, 76 bytes long.
Data: <d ,g s L Bg> 64 D2 2C 67 A8 73 A4 00 00 00 00 00 4C B9 42 67
{5565} normal block at 0x00A473A8, 12 bytes long.
Data: < s > E0 D7 C3 00 F0 73 A4 00 CC D7 C3 00
{5563} normal block at 0x00A471E0, 128 bytes long.
Data: < 6 5 q > 01 00 00 00 36 00 00 00 35 00 00 00 F2 71 A4 00
{5543} normal block at 0x00A47008, 76 bytes long.
Data: <d ,g o L Bg> 64 D2 2C 67 C0 6F A4 00 00 00 00 00 4C B9 42 67
{5542} normal block at 0x00A46FC0, 12 bytes long.
Data: <La p 8a > 4C 61 BB 00 08 70 A4 00 38 61 BB 00
{5540} normal block at 0x00A46DF8, 128 bytes long.
Data: < 6 6 n > 01 00 00 00 36 00 00 00 36 00 00 00 0A 6E A4 00
{5520} normal block at 0x003ED9A8, 76 bytes long.
Data: <d ,g` > L Bg> 64 D2 2C 67 60 D9 3E 00 00 00 00 00 4C B9 42 67
{5519} normal block at 0x003ED960, 12 bytes long.
Data: < > > A4 C6 B4 00 A8 D9 3E 00 90 C6 B4 00
{5517} normal block at 0x00A46D38, 128 bytes long.
Data: < 6 5 Jm > 01 00 00 00 36 00 00 00 35 00 00 00 4A 6D A4 00
{5496} normal block at 0x003ED8D8, 76 bytes long.
Data: <d ,g > L Bg> 64 D2 2C 67 80 D7 3E 00 00 00 00 00 4C B9 42 67
{5495} normal block at 0x003ED780, 12 bytes long.
Data: << > ( > 3C CA 00 10 D8 D8 3E 00 28 CA 00 10
{5491} normal block at 0x00A412A0, 128 bytes long.
Data: < 6 5 > 01 00 00 00 36 00 00 00 35 00 00 00 B2 12 A4 00
{5260} normal block at 0x00A48448, 64 bytes long.
Data: < Z > 01 00 00 00 16 00 00 00 13 00 00 00 5A 84 A4 00
{5233} normal block at 0x00A48380, 56 bytes long.
Data: < Ha Bg> 00 00 CD 00 C0 82 A4 00 48 61 A4 00 04 BA 42 67
{5231} normal block at 0x00A482C0, 128 bytes long.
Data: < 6 6 > 01 00 00 00 36 00 00 00 36 00 00 00 D2 82 A4 00
{4681} normal block at 0x00A48150, 64 bytes long.
Data: < b > 01 00 00 00 16 00 00 00 13 00 00 00 62 81 A4 00
{4655} normal block at 0x00A47FB8, 56 bytes long.
Data: < ~ H\ Bg> 00 00 CA 00 F8 7E A4 00 48 5C A4 00 04 BA 42 67
{4653} normal block at 0x00A47EF8, 126 bytes long.
Data: < 5 5 > 01 00 00 00 35 00 00 00 35 00 00 00 0A 7F A4 00
{4102} normal block at 0x00A47DB8, 64 bytes long.
Data: < } > 01 00 00 00 16 00 00 00 13 00 00 00 CA 7D A4 00
{4075} normal block at 0x00A47D40, 56 bytes long.
Data: < { [ Bg> 00 00 C6 00 D8 7B A4 00 88 5B A4 00 04 BA 42 67
{4073} normal block at 0x00A47BD8, 126 bytes long.
Data: < 5 5 { > 01 00 00 00 35 00 00 00 35 00 00 00 EA 7B A4 00
{3522} normal block at 0x00A479F8, 64 bytes long.
Data: < z > 01 00 00 00 16 00 00 00 13 00 00 00 0A 7A A4 00
{3496} normal block at 0x00A47AA0, 56 bytes long.
Data: < 8y q Bg> 00 00 BD 00 38 79 A4 00 E0 71 A4 00 04 BA 42 67
{3494} normal block at 0x00A47938, 126 bytes long.
Data: < 5 5 Jy > 01 00 00 00 35 00 00 00 35 00 00 00 4A 79 A4 00
{2943} normal block at 0x00A41220, 64 bytes long.
Data: < 2 > 01 00 00 00 16 00 00 00 13 00 00 00 32 12 A4 00
{2917} normal block at 0x00A40418, 56 bytes long.
Data: < X m Bg> 00 00 B6 00 58 03 A4 00 F8 6D A4 00 04 BA 42 67
{2915} normal block at 0x00A40358, 128 bytes long.
Data: < 6 6 j > 01 00 00 00 36 00 00 00 36 00 00 00 6A 03 A4 00
{2367} normal block at 0x00A40760, 64 bytes long.
Data: < r > 01 00 00 00 16 00 00 00 13 00 00 00 72 07 A4 00
{2341} normal block at 0x00A401D0, 56 bytes long.
Data: < h 8m Bg> 00 00 B4 00 68 00 A4 00 38 6D A4 00 04 BA 42 67
{2339} normal block at 0x00A40068, 126 bytes long.
Data: < 5 5 z > 01 00 00 00 35 00 00 00 35 00 00 00 7A 00 A4 00
{1788} normal block at 0x00A40820, 64 bytes long.
Data: < 2 > 01 00 00 00 16 00 00 00 13 00 00 00 32 08 A4 00
{1762} normal block at 0x00A417B0, 56 bytes long.
Data: < Bg> 00 00 00 10 B0 18 A4 00 A0 12 A4 00 04 BA 42 67
{1760} normal block at 0x00A418B0, 126 bytes long.
Data: < 5 5 > 01 00 00 00 35 00 00 00 35 00 00 00 C2 18 A4 00
{252} normal block at 0x003E8A08, 40 bytes long.
Data: < @B > 00 00 00 00 CC CD CD CD 40 42 0F 00 00 00 00 00
{251} normal block at 0x003E8950, 120 bytes long.
Data: <Lc-g > L Bg> 4C 63 2D 67 08 89 3E 00 00 00 00 00 4C B9 42 67
{250} normal block at 0x003E8908, 8 bytes long.
Data: < c-gP > > 0C 63 2D 67 50 89 3E 00
{249} normal block at 0x003E88A0, 40 bytes long.
Data: < @B > 00 00 00 00 CC CD CD CD 40 42 0F 00 00 00 00 00
{248} normal block at 0x003E8828, 60 bytes long.
Data: < > > 07 00 00 00 08 89 3E 00 80 06 00 00 00 CD CD CD
Object dump complete.
The program '[2808] QtSandBoxApp.exe: Native' has exited with code 0 (0x0).
我解决了这个问题。 似乎使用CrtDbg库API对Qt来说不是一个好主意。
来自http://winfig.com/?p=154的报价：
Qt在其DLL中分配内存，并在卸载DLL时释放此内存。不幸的是，这是在Visual Studio报告所谓的泄漏之后。
这是事实，当我从磁盘请求QImage时，在运行时加载以下模块：
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qgifd4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qicod4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qjpegd4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qmngd4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qsvgd4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\bin\QtSvgd4.dll', Symbols loaded.
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\bin\QtXmld4.dll', Symbols loaded.
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qtgad4.dll'
'QtSandBoxApp.exe': Loaded 'C:\Libraries\Qt\4.8.1\plugins\imageformats\qtiffd4.dll'
Visual Leak Detector正确报告没有内存泄漏。
P.S：来自QtCentre的This wiki条目具有误导性：P
另一种避免内存泄漏的方法，你可以使用QPcon调用QIix，在你的例子中如下：
QTreeWidgetItem *newItem = new QTreeWidgetItem();
newItem->setText(0, "Item");
// This causes a memory leak!
newItem->setIcon(0, QIcon(QPixmap("D:\\Dnl\\QtSandBoxApp\\Resources\\dataset2.png")));
treeWidget->addTopLevelItem(newItem);
正如我在我的博客（https://programmersexception.blogspot.com/2019/04/memory-leak-con-qicon-en-qt-594-y.html）中解释的那样，抱歉是西班牙语，有已知的BUG，我希望他们很快就能解决（https://bugreports.qt.io/browse/QTBUG-59621）。