valgrind 的一个小缺陷

valgrind 在项目中， 通常被用来做内存泄露的检查， 性能分析。

近期在使用valgrind做内存泄露， 忽略了此处testcode中的泄露提醒， 结果将代码提交上去后， 发现还是有内存的泄露， 被同事“嘲笑”了一番。

写了一小段代码， 来表述这个问题

 

class A

{

public:

  A(size_t s)

{

m_pdata = new int[s];

} 

private:

int *m_pdata; 

} ;

 nt main()

{

    A *pa = new A(5);

    return 0;

}

 

/*****************************************************/

可以看出， 内存泄露的地方有两处， 一个出 main中， 一处是 class A 的构造函数中。 

 而再看看valgrind的提示信息

[tianduo@search041144.sqa.cm4 c++]$ valgrind --leak-check=yes ./a.out  

==4049== Memcheck, a memory error detector.

==4049== Copyright (C) 2002-2006, and GNU GPL'd, by Julian Seward et al.

==4049== Using LibVEX rev 1658, a library for dynamic binary translation.

==4049== Copyright (C) 2004-2006, and GNU GPL'd, by OpenWorks LLP.

==4049== Using valgrind-3.2.1, a dynamic binary instrumentation framework.

==4049== Copyright (C) 2000-2006, and GNU GPL'd, by Julian Seward et al.

==4049== For more details, rerun with: -v

==4049== 

==4049== 

==4049== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 5 from 1)

==4049== malloc/free: in use at exit: 28 bytes in 2 blocks.

==4049== malloc/free: 2 allocs, 0 frees, 28 bytes allocated.

==4049== For counts of detected errors, rerun with: -v

==4049== searching for pointers to 2 not-freed blocks.

==4049== checked 163,288 bytes.

==4049== 

==4049== 28 (8 direct, 20 indirect) bytes in 1 blocks are definitely lost in loss record 1 of 2

==4049==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)

==4049==    by 0x4006AA: main (memory.cpp:14)

==4049== 

==4049== LEAK SUMMARY:

==4049==    definitely lost: 8 bytes in 1 blocks.

==4049==    indirectly lost: 20 bytes in 1 blocks.

==4049==      possibly lost: 0 bytes in 0 blocks.

==4049==    still reachable: 0 bytes in 0 blocks.

==4049==         suppressed: 0 bytes in 0 blocks.

==4049== Reachable blocks (those to which a pointer was found) are not shown.

==4049== To see them, rerun with: --show-reachable=yes 

 粗略一看， 只有  main函数的14行， 如果在测试的时候， 认为忽略这一行， 那就遗漏了 class A中的泄露点。