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【Visual Leak Detector】配置项 SkipHeapFreeLeaks

  • Post category:C++

说明

使用 VLD 内存泄漏检测工具辅助开发时整理的学习笔记。本篇介绍 VLD 配置文件中配置项 SkipHeapFreeLeaks 的使用方法。同系列文章目录可见 《内存泄漏检测工具》目录

目录

1. 配置文件使用说明

在程序中通过 #include "vld.h" 的方式检测内存泄漏时，VLD 首先会尝试在程序的生成目录下读取 vld.ini 文件，若未读取成功，则会尝试在 VLD 的安装目录下读取 vld.ini 文件，若仍未读取成功，则会使用内置的默认配置，内置的默认配置如果不动源码是无法更改的，因此通过修改相应目录下的 vld.ini 文件来定制 VLD 功能是最好的选择。当配置参数等号右边为空，或者给配置了不合法值时，在使用过程中会被程序重置到默认值。

2. 设置是否跳过堆内存泄漏检测

参数名：SkipHeapFreeLeaks。

有效赋值：yes，no。

默认值：no。

功能说明：文档原话 是 Determines whether or not report memory leaks when missing HeapFree calls. 但是当我把这个变量设置为 yes 时仍可以检测到堆上的内存泄漏，这个配置项的实际作用有待进一步研究。

2.1 测试代码

#include <QCoreApplication>
#include "Windows.h"
#include "vld.h"

void testFun(int i)
{
    int *ptr = new int(i);
    printf("ptr = %08x, *ptr = %08x.\n", ptr, *ptr);

    int *pData= (int *)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(int));
    printf("pData = %08x, *pData = %08x.\n", pData, *pData);
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    testFun(1);

    return a.exec();
}

测试环境：QT 5.9.2，MSVC 2015 32bit，Debug 模式，VLD 版本为 2.5.1，VLD 配置文件只对该参数做修改，测试工程所在路径为：E:\Cworkspace\Qt 5.9\QtDemo\testVLD。

2.2 SkipHeapFreeLeaks = no 时的输出

标准输出窗显示：

ptr = 00539498, *ptr = 00000001.
pData = 00535720, *pData = 00000000.

VLD 输出报告：

Visual Leak Detector read settings from: D:\Program Files (x86)\Visual Leak Detector\vld.ini
Visual Leak Detector Version 2.5.1 installed.
WARNING: Visual Leak Detector detected memory leaks!
---------- Block 2 at 0x00535720: 4 bytes ----------
  Leak Hash: 0x426C3DE0, Count: 1, Total 4 bytes
  Call Stack (TID 30052):
    ntdll.dll!RtlAllocateHeap()
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (10): testVLD.exe!testFun() + 0x11 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (18): testVLD.exe!main() + 0x7 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (74): testVLD.exe!invoke_main() + 0x1B bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (264): testVLD.exe!__scrt_common_main_seh() + 0x5 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (309): testVLD.exe!__scrt_common_main()
    f:\dd\vctools\crt\vcstartup\src\startup\exe_main.cpp (17): testVLD.exe!mainCRTStartup()
    KERNEL32.DLL!BaseThreadInitThunk() + 0x19 bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0x11E bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0xEE bytes
  Data:
    00 00 00 00                                                  ........ ........


---------- Block 1 at 0x00539498: 4 bytes ----------
  Leak Hash: 0x19BB156F, Count: 1, Total 4 bytes
  Call Stack (TID 30052):
    ucrtbased.dll!malloc()
    f:\dd\vctools\crt\vcstartup\src\heap\new_scalar.cpp (19): testVLD.exe!operator new() + 0x9 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (7): testVLD.exe!testFun() + 0x7 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (18): testVLD.exe!main() + 0x7 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (74): testVLD.exe!invoke_main() + 0x1B bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (264): testVLD.exe!__scrt_common_main_seh() + 0x5 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (309): testVLD.exe!__scrt_common_main()
    f:\dd\vctools\crt\vcstartup\src\startup\exe_main.cpp (17): testVLD.exe!mainCRTStartup()
    KERNEL32.DLL!BaseThreadInitThunk() + 0x19 bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0x11E bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0xEE bytes
  Data:
    01 00 00 00                                                  ........ ........


Visual Leak Detector detected 2 memory leaks (44 bytes).
Largest number used: 44 bytes.
Total allocations: 44 bytes.
Visual Leak Detector is now exiting.

2.3 SkipHeapFreeLeaks = yes 时的输出

标准输出窗显示：

ptr = 014e9450, *ptr = 00000001.
pData = 014e84b0, *pData = 00000000.

VLD 输出报告：

Visual Leak Detector read settings from: D:\Program Files (x86)\Visual Leak Detector\vld.ini
Visual Leak Detector Version 2.5.1 installed.
WARNING: Visual Leak Detector detected memory leaks!
---------- Block 2 at 0x014E84B0: 4 bytes ----------
  Leak Hash: 0x7C37FF93, Count: 1, Total 4 bytes
  Call Stack (TID 7564):
    ntdll.dll!RtlAllocateHeap()
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (10): testVLD.exe!testFun() + 0x11 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (18): testVLD.exe!main() + 0x7 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (74): testVLD.exe!invoke_main() + 0x1B bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (264): testVLD.exe!__scrt_common_main_seh() + 0x5 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (309): testVLD.exe!__scrt_common_main()
    f:\dd\vctools\crt\vcstartup\src\startup\exe_main.cpp (17): testVLD.exe!mainCRTStartup()
    KERNEL32.DLL!BaseThreadInitThunk() + 0x19 bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0x11E bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0xEE bytes
  Data:
    00 00 00 00                                                  ........ ........


---------- Block 1 at 0x014E9450: 4 bytes ----------
  Leak Hash: 0x8876C556, Count: 1, Total 4 bytes
  Call Stack (TID 7564):
    ucrtbased.dll!malloc()
    f:\dd\vctools\crt\vcstartup\src\heap\new_scalar.cpp (19): testVLD.exe!operator new() + 0x9 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (7): testVLD.exe!testFun() + 0x7 bytes
    e:\cworkspace\qt 5.9\qtdemo\testvld\main.cpp (18): testVLD.exe!main() + 0x7 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (74): testVLD.exe!invoke_main() + 0x1B bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (264): testVLD.exe!__scrt_common_main_seh() + 0x5 bytes
    f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl (309): testVLD.exe!__scrt_common_main()
    f:\dd\vctools\crt\vcstartup\src\startup\exe_main.cpp (17): testVLD.exe!mainCRTStartup()
    KERNEL32.DLL!BaseThreadInitThunk() + 0x19 bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0x11E bytes
    ntdll.dll!RtlGetAppContainerNamedObjectPath() + 0xEE bytes
  Data:
    01 00 00 00                                                  ........ ........


Visual Leak Detector detected 2 memory leaks (44 bytes).
Largest number used: 44 bytes.
Total allocations: 44 bytes.
Visual Leak Detector is now exiting.

2.4 输出结果对比

SkipHeapFreeLeaks = no 与 SkipHeapFreeLeaks = yes 的输出结果似乎没有什么实质性的差异，不过有一点需注意，使用 new 分配堆内存时，会额外添加 36 bytes 大小的内存用于追踪管理，但使用 HeapAlloc() 函数分配堆内存时，则没有额外的内存使用，因此上述测试例的 Total allocations 为 44 bytes，而不是 80 bytes。

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