CODEWITHSUNDEEP
c++qtvalgrind
Christopher Pisz
Christopher Pisz

Reputation: 4000

Qt QMainWindow - Valgrind reports memory leaks

I was getting reports of memory leaks from valgrind in my production code. So, naturally, I narrowed it down to a minimal compilable example. Strange thins is, I had to "minimize it", so much, that there is nothing left except instantiation of a Qt Window!

Is Qt bugged? Did I not invoke valgrind properly?

My tools and versions, from Centos 7:

cmake3 3.17.2
gcc 8.3.1
Qt 5.14
valgrind 3.14.0

It is currently checked it into my github at https://github.com/ChristopherPisz/QMainWindowLeaks However, I will list it here for the future when it isn't there any longer.

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Qt MainWindow Leaks</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <property name="sizePolicy">
    <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
     <horstretch>1</horstretch>
     <verstretch>1</verstretch>
    </sizepolicy>
   </property>
   <layout class="QHBoxLayout" name="horizontalLayout"/>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>25</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
  <action name="actionExit">
   <property name="text">
    <string>Exit</string>
   </property>
  </action>
 </widget>
 <resources/>
 <connections/>
</ui>

mainwindow.hpp

#ifndef QTPROBLEMS_MAINWINDOW_HPP
#define QTPROBLEMS_MAINWINDOW_HPP

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui
{
    class MainWindow;
}
QT_END_NAMESPACE


class MainWindow final : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget* parent = nullptr);
    ~MainWindow() override;

private:
    Ui::MainWindow* m_ui;  ///< Qt generated object that is the main window
};
#endif

mainwindow.cpp

#include "mainwindow.hpp"
#include "./ui_mainwindow.h"


MainWindow::MainWindow(QWidget* parent)
        : QMainWindow(parent)
        , m_ui(new Ui::MainWindow)
{
    m_ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete m_ui;
}

main.cpp

#include "mainwindow.hpp"
#include <iostream>
#include <QtWidgets/QApplication>


int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    MainWindow window;
    window.show();

    int returnCode = 1;
    try
    {
        returnCode = QApplication::exec();
    }
    catch(std::exception& e)
    {
        std::cerr << "An unhandled std::exception has escaped the main event loop: {}", e.what();
    }
    catch(...)
    {
        std::cerr << "An unhandled exception, of unknown type, has escaped the main event loop";
    }

    return returnCode;
}

CmakeLists.txt

cmake_minimum_required(VERSION 3.0)
project(qtproblems)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTORCC ON)

find_package(Qt5 5.14 REQUIRED COMPONENTS Core Widgets)

set(MOC_HEADERS
    mainwindow.hpp
    )

set(UI_FORMS
    mainwindow.ui
    )


add_executable(qtproblems
        ${MOC_HEADERS}
        ${UI_FORMS}
        mainwindow.cpp
        main.cpp
        )

target_link_libraries(qtproblems PRIVATE
        Qt5::Core
        Qt5::Widgets
        )

Output:

==26444== Memcheck, a memory error detector
==26444== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==26444== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==26444== Command: /home/cpisz/git-workspace/QMainWindowLeaks/cmake-build-debug/qtproblems
==26444== Parent PID: 31394
==26444== 
==26444== 
==26444== HEAP SUMMARY:
==26444==     in use at exit: 305,230 bytes in 6,852 blocks
==26444==   total heap usage: 107,812 allocs, 100,960 frees, 232,668,695 bytes allocated
==26444== 
==26444== 38 bytes in 1 blocks are definitely lost in loss record 73 of 284
==26444==    at 0x4C29E63: malloc (vg_replace_malloc.c:309)
==26444==    by 0x1664CF1E: ???
==26444==    by 0x1662FC54: ???
==26444==    by 0x1327FC80: q_dbus_bus_get_private(DBusBusType, DBusError*) (qdbus_symbols_p.h:198)
==26444==    by 0x13280818: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:263)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444==    by 0x670D63C: QtPrivate::QSlotObjectBase::call(QObject*, void**) (qobjectdefs_impl.h:394)
==26444==    by 0x673DB2E: QMetaCallEvent::placeMetaCall(QObject*) (qobject.cpp:619)
==26444==    by 0x673EAF3: QObject::event(QEvent*) (qobject.cpp:1339)
==26444==    by 0x649CA55: QThread::event(QEvent*) (qthread.cpp:980)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   obj:*
   obj:*
   fun:_ZL22q_dbus_bus_get_private11DBusBusTypeP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
   fun:_ZN9QtPrivate15QSlotObjectBase4callEP7QObjectPPv
   fun:_ZN14QMetaCallEvent13placeMetaCallEP7QObject
   fun:_ZN7QObject5eventEP6QEvent
   fun:_ZN7QThread5eventEP6QEvent
}
==26444== 72 (24 direct, 48 indirect) bytes in 1 blocks are definitely lost in loss record 141 of 284
==26444==    at 0x4C29E63: malloc (vg_replace_malloc.c:309)
==26444==    by 0x1664ED05: ???
==26444==    by 0x1664ED66: ???
==26444==    by 0x1662F97D: ???
==26444==    by 0x1327FC80: q_dbus_bus_get_private(DBusBusType, DBusError*) (qdbus_symbols_p.h:198)
==26444==    by 0x13280818: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:263)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444==    by 0x670D63C: QtPrivate::QSlotObjectBase::call(QObject*, void**) (qobjectdefs_impl.h:394)
==26444==    by 0x673DB2E: QMetaCallEvent::placeMetaCall(QObject*) (qobject.cpp:619)
==26444==    by 0x673EAF3: QObject::event(QEvent*) (qobject.cpp:1339)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   obj:*
   obj:*
   obj:*
   fun:_ZL22q_dbus_bus_get_private11DBusBusTypeP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
   fun:_ZN9QtPrivate15QSlotObjectBase4callEP7QObjectPPv
   fun:_ZN14QMetaCallEvent13placeMetaCallEP7QObject
   fun:_ZN7QObject5eventEP6QEvent
}
==26444== 73 bytes in 1 blocks are definitely lost in loss record 142 of 284
==26444==    at 0x4C29E63: malloc (vg_replace_malloc.c:309)
==26444==    by 0x1664CF1E: ???
==26444==    by 0x1662F3B4: ???
==26444==    by 0x1662FAC2: ???
==26444==    by 0x1327FC80: q_dbus_bus_get_private(DBusBusType, DBusError*) (qdbus_symbols_p.h:198)
==26444==    by 0x13280818: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:263)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444==    by 0x670D63C: QtPrivate::QSlotObjectBase::call(QObject*, void**) (qobjectdefs_impl.h:394)
==26444==    by 0x673DB2E: QMetaCallEvent::placeMetaCall(QObject*) (qobject.cpp:619)
==26444==    by 0x673EAF3: QObject::event(QEvent*) (qobject.cpp:1339)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   obj:*
   obj:*
   obj:*
   fun:_ZL22q_dbus_bus_get_private11DBusBusTypeP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
   fun:_ZN9QtPrivate15QSlotObjectBase4callEP7QObjectPPv
   fun:_ZN14QMetaCallEvent13placeMetaCallEP7QObject
   fun:_ZN7QObject5eventEP6QEvent
}
==26444== 73 bytes in 1 blocks are definitely lost in loss record 143 of 284
==26444==    at 0x4C29E63: malloc (vg_replace_malloc.c:309)
==26444==    by 0x1664CF1E: ???
==26444==    by 0x1662FCAD: ???
==26444==    by 0x1327FC80: q_dbus_bus_get_private(DBusBusType, DBusError*) (qdbus_symbols_p.h:198)
==26444==    by 0x13280818: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:263)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444==    by 0x670D63C: QtPrivate::QSlotObjectBase::call(QObject*, void**) (qobjectdefs_impl.h:394)
==26444==    by 0x673DB2E: QMetaCallEvent::placeMetaCall(QObject*) (qobject.cpp:619)
==26444==    by 0x673EAF3: QObject::event(QEvent*) (qobject.cpp:1339)
==26444==    by 0x649CA55: QThread::event(QEvent*) (qthread.cpp:980)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   obj:*
   obj:*
   fun:_ZL22q_dbus_bus_get_private11DBusBusTypeP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
   fun:_ZN9QtPrivate15QSlotObjectBase4callEP7QObjectPPv
   fun:_ZN14QMetaCallEvent13placeMetaCallEP7QObject
   fun:_ZN7QObject5eventEP6QEvent
   fun:_ZN7QThread5eventEP6QEvent
}
==26444== 520 bytes in 13 blocks are definitely lost in loss record 198 of 284
==26444==    at 0x4C29E63: malloc (vg_replace_malloc.c:309)
==26444==    by 0x16655141: ???
==26444==    by 0x16648EF4: ???
==26444==    by 0x16649068: ???
==26444==    by 0x1664D509: ???
==26444==    by 0x16641F8A: ???
==26444==    by 0x1327FDED: q_dbus_get_local_machine_id() (qdbus_symbols_p.h:435)
==26444==    by 0x13282716: QDBusConnection::localMachineId() (qdbusconnection.cpp:1251)
==26444==    by 0x163F7054: QIBusPlatformInputContextPrivate::getSocketPath() (qibusplatforminputcontext.cpp:733)
==26444==    by 0x163F72B0: QIBusPlatformInputContextPrivate::createConnection() (qibusplatforminputcontext.cpp:741)
==26444==    by 0x163F675F: QIBusPlatformInputContextPrivate::initBus() (qibusplatforminputcontext.cpp:648)
==26444==    by 0x163F669E: QIBusPlatformInputContextPrivate::QIBusPlatformInputContextPrivate() (qibusplatforminputcontext.cpp:638)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   fun:_ZL27q_dbus_get_local_machine_idv
   fun:_ZN15QDBusConnection14localMachineIdEv
   fun:_ZN32QIBusPlatformInputContextPrivate13getSocketPathEv
   fun:_ZN32QIBusPlatformInputContextPrivate16createConnectionEv
   fun:_ZN32QIBusPlatformInputContextPrivate7initBusEv
   fun:_ZN32QIBusPlatformInputContextPrivateC1Ev
}
==26444== 545 (184 direct, 361 indirect) bytes in 1 blocks are definitely lost in loss record 199 of 284
==26444==    at 0x4C2BF79: calloc (vg_replace_malloc.c:762)
==26444==    by 0x1663CA74: ???
==26444==    by 0x166414AE: ???
==26444==    by 0x16649CB7: ???
==26444==    by 0x16649DD2: ???
==26444==    by 0x1664A87E: ???
==26444==    by 0x1664B0F0: ???
==26444==    by 0x16649A77: ???
==26444==    by 0x16632FCC: ???
==26444==    by 0x1328AB07: q_dbus_watch_handle(DBusWatch*, unsigned int) (qdbus_symbols_p.h:275)
==26444==    by 0x13290700: QDBusConnectionPrivate::socketRead(int) (qdbusintegrator.cpp:1213)
==26444==    by 0x132A6513: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<int>, void, void (QDBusConnectionPrivate::*)(int)>::call(void (QDBusConnectionPrivate::*)(int), QDBusConnectionPrivate*, void**) (qobjectdefs_impl.h:152)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:calloc
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   fun:_ZL19q_dbus_watch_handleP9DBusWatchj
   fun:_ZN22QDBusConnectionPrivate10socketReadEi
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJiEEEvM22QDBusConnectionPrivateFviEE4callES7_PS5_PPv
}
==26444== 727 (184 direct, 543 indirect) bytes in 1 blocks are definitely lost in loss record 208 of 284
==26444==    at 0x4C2BF79: calloc (vg_replace_malloc.c:762)
==26444==    by 0x1663CA74: ???
==26444==    by 0x1663D871: ???
==26444==    by 0x1662F774: ???
==26444==    by 0x1327FC3B: q_dbus_bus_register(DBusConnection*, DBusError*) (qdbus_symbols_p.h:195)
==26444==    by 0x132808BE: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:276)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444==    by 0x670D63C: QtPrivate::QSlotObjectBase::call(QObject*, void**) (qobjectdefs_impl.h:394)
==26444==    by 0x673DB2E: QMetaCallEvent::placeMetaCall(QObject*) (qobject.cpp:619)
==26444==    by 0x673EAF3: QObject::event(QEvent*) (qobject.cpp:1339)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:calloc
   obj:*
   obj:*
   obj:*
   fun:_ZL19q_dbus_bus_registerP14DBusConnectionP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
   fun:_ZN9QtPrivate15QSlotObjectBase4callEP7QObjectPPv
   fun:_ZN14QMetaCallEvent13placeMetaCallEP7QObject
   fun:_ZN7QObject5eventEP6QEvent
}
==26444== 727 (184 direct, 543 indirect) bytes in 1 blocks are definitely lost in loss record 209 of 284
==26444==    at 0x4C2BF79: calloc (vg_replace_malloc.c:762)
==26444==    by 0x1663CA74: ???
==26444==    by 0x166409BA: ???
==26444==    by 0x16643857: ???
==26444==    by 0x166336FD: ???
==26444==    by 0x166339BF: ???
==26444==    by 0x1662F793: ???
==26444==    by 0x1327FC3B: q_dbus_bus_register(DBusConnection*, DBusError*) (qdbus_symbols_p.h:195)
==26444==    by 0x132808BE: QDBusConnectionManager::executeConnectionRequest(QDBusConnectionManager::ConnectionRequestData*) (qdbusconnection.cpp:276)
==26444==    by 0x13286D27: QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void, void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:152)
==26444==    by 0x13286ABC: void QtPrivate::FunctionPointer<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*)>::call<QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>(void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QDBusConnectionManager*, void**) (qobjectdefs_impl.h:185)
==26444==    by 0x13285FF3: QtPrivate::QSlotObject<void (QDBusConnectionManager::*)(QDBusConnectionManager::ConnectionRequestData*), QtPrivate::List<QDBusConnectionManager::ConnectionRequestData*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:calloc
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   fun:_ZL19q_dbus_bus_registerP14DBusConnectionP9DBusError
   fun:_ZN22QDBusConnectionManager24executeConnectionRequestEPNS_21ConnectionRequestDataE
   fun:_ZN9QtPrivate11FunctorCallINS_11IndexesListIJLi0EEEENS_4ListIJPN22QDBusConnectionManager21ConnectionRequestDataEEEEvMS4_FvS6_EE4callES9_PS4_PPv
   fun:_ZN9QtPrivate15FunctionPointerIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEEE4callINS_4ListIJS3_EEEvEEvS5_PS1_PPv
   fun:_ZN9QtPrivate11QSlotObjectIM22QDBusConnectionManagerFvPNS1_21ConnectionRequestDataEENS_4ListIJS3_EEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb
}
==26444== 1,119 (368 direct, 751 indirect) bytes in 2 blocks are definitely lost in loss record 232 of 284
==26444==    at 0x4C2BF79: calloc (vg_replace_malloc.c:762)
==26444==    by 0x1663CA74: ???
==26444==    by 0x166414AE: ???
==26444==    by 0x16649CB7: ???
==26444==    by 0x16649DD2: ???
==26444==    by 0x1664A87E: ???
==26444==    by 0x1664AFD5: ???
==26444==    by 0x16649B79: ???
==26444==    by 0x166329FB: ???
==26444==    by 0x166333DC: ???
==26444==    by 0x166339D9: ???
==26444==    by 0x1662F793: ???
==26444== 
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:calloc
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
   obj:*
}
==26444== LEAK SUMMARY:
==26444==    definitely lost: 1,648 bytes in 22 blocks
==26444==    indirectly lost: 2,246 bytes in 12 blocks
==26444==      possibly lost: 0 bytes in 0 blocks
==26444==    still reachable: 301,336 bytes in 6,818 blocks
==26444==         suppressed: 0 bytes in 0 blocks
==26444== Reachable blocks (those to which a pointer was found) are not shown.
==26444== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==26444== 
==26444== For counts of detected and suppressed errors, rerun with: -v
==26444== ERROR SUMMARY: 9 errors from 9 contexts (suppressed: 0 from 0)

Upvotes: 1

Views: 1514

Answers (1)

hyde
hyde

Reputation: 62777

This is normal for certain kind of libraries, such as C standard library. This is why you want Valgrind suppression files, so it knows which leaks are normal. To easily have nice suppression data for Qt, run Valgrind under Qt Creator (documentation link).

The reason for this is, libraries reserve memory for things like communicating with the operating system stuff (such as windowing system), but have no control over when your application no longer needs it. It could be released at application exit via exit hooks, but the entire application is going to be removed from memory, so doing memory cleanup would just slow down application shutdown for literally no gain at all.

Note that most memory is still cleaned up as C++ objects go out of scope. C++ objects need to have their destructors called anyway, which is normally done by delete for objects in heap. Also this is definitely not something you should optimize for in a normal C++ application code. The stuff libraries leave allocated at exit (and need Valgrind suppression) are typically low level stuff, global to the whole application and not owned by a single C++ object instance.

Upvotes: 2

Related Questions