c++ - 不同机器上的不同 Valgrind 输出

Question

我有一个奇怪的情况，即完全相同的可执行文件的 Valgrind 输出在一台机器上与另一台机器上不同。

我正在用 C++ 编写一个 Windows 注册表读/写库，并且我一直试图在编写代码时非常健壮。因此，我一直在运行 Valgrind 并修复内存泄漏，因为它们是通过从一组单元测试生成的可执行文件引入的。

我的主要开发 PC 运行的是 Linux Mint Debian Edition x86_64。一个周末，我将我的存储库克隆到运行 Arch x86_64 的笔记本电脑上，然后我开始在 Valgrind 中出现内存泄漏(或者更确切地说，仍然可访问的 block )。经过多次摸索后，我意识到即使是最后一次在 Mint DE 上干净的提交在 Arch 上也显示出泄漏。我还注意到 Arch 盒子上的 allocs 数量超过四倍，尽管我不知道这是否意味着什么。

这是我在两台机器上使用相同 exe 的结果(在一台机器上编译并复制到另一台机器):

薄荷德 x86_64:

valgrind --leak-check=full --show-leak-kinds=all ./regnixtest
==12248== Memcheck, a memory error detector
==12248== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==12248== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==12248== Command: ./regnixtest
==12248== 
Testing Create Valid NK...passed
[ normal command output snipped for brevity ]
==12248== 
==12248== HEAP SUMMARY:
==12248==     in use at exit: 0 bytes in 0 blocks
==12248==   total heap usage: 603 allocs, 603 frees, 608,657,070 bytes allocated
==12248== 
==12248== All heap blocks were freed -- no leaks are possible
==12248== 
==12248== For counts of detected and suppressed errors, rerun with: -v
==12248== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

架构 x86_64:

valgrind --leak-check=full --show-leak-kinds=all ./regnixtest 
==5006== Memcheck, a memory error detector
==5006== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==5006== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==5006== Command: ./regnixtest
==5006== 
Testing Create Valid NK...passed
[ normal command output snipped for brevity ]
==5006== 
==5006== HEAP SUMMARY:
==5006==     in use at exit: 72,704 bytes in 1 blocks
==5006==   total heap usage: 2,927 allocs, 2,926 frees, 608,844,359 bytes allocated
==5006== 
==5006== 72,704 bytes in 1 blocks are still reachable in loss record 1 of 1
==5006==    at 0x4C29F90: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==5006==    by 0x4EC01EF: pool (eh_alloc.cc:117)
==5006==    by 0x4EC01EF: __static_initialization_and_destruction_0 (eh_alloc.cc:244)
==5006==    by 0x4EC01EF: _GLOBAL__sub_I_eh_alloc.cc (eh_alloc.cc:307)
==5006==    by 0x400F0E9: call_init.part.0 (in /usr/lib/ld-2.21.so)
==5006==    by 0x400F1FA: _dl_init (in /usr/lib/ld-2.21.so)
==5006==    by 0x4000DB9: ??? (in /usr/lib/ld-2.21.so)
==5006== 
==5006== LEAK SUMMARY:
==5006==    definitely lost: 0 bytes in 0 blocks
==5006==    indirectly lost: 0 bytes in 0 blocks
==5006==      possibly lost: 0 bytes in 0 blocks
==5006==    still reachable: 72,704 bytes in 1 blocks
==5006==         suppressed: 0 bytes in 0 blocks
==5006== 
==5006== For counts of detected and suppressed errors, rerun with: -v
==5006== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

这是我 Arch box 上的某个库的问题吗？以下是 ldd 的输出，以防万一:

薄荷德 x86_64:

ldd ./regnixtest
linux-vdso.so.1 (0x00007ffc76ffc000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f080dcaa000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f080d9a9000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f080d792000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f080d3e9000)
/lib64/ld-linux-x86-64.so.2 (0x00007f080dfd2000)

架构 x86_64:

ldd ./regnixtest
linux-vdso.so.1 (0x00007ffd81bd5000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007fcf9d788000)
libm.so.6 => /usr/lib/libm.so.6 (0x00007fcf9d484000)
libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007fcf9d26e000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007fcf9cecc000)
/lib64/ld-linux-x86-64.so.2 (0x00007fcf9db0a000)

这个项目最终会开源，但我还没有准备好将代码放在那里。如果有帮助，我可以继续将它放在 GitHub 上。

Answer 1

在撰写本文时，Mint 具有 gcc 4.x 而 Arch 具有 gcc 5.2，因此存在差异。这个用 g++ 5.2 编译并在 Arch 上使用相同的 valgrind 选项运行的简单程序显示了相同的“泄漏”。

int main(void)
{
    return 0;
}

如果您担心噪声会隐藏实际问题，只需对此警告添加抑制。