Valgrind内存泄露检测工具使用初步

一、前言

上次阿里电话面试，被问到了内存泄露的解决办法，但是我只知道智能指针，面试官问我还有其他办法吗，我没答上来。后来一查才知道可以有专门的工具用来检测，今天把这个工具简单实践一下。

Valgrind是一套可以用于内存检测、线程错误检测、性能分析等的工具集。

memcheck是其中一个内存错误检测器，今天主要学习这个工具。

二、安装

从官网下载源代码并解压：valgrind-3.9.0.tar.bz2

gzip2 -d valgrind-3.9.0.tar.bz2
tar xvf valgrind-3.9.0.tar

安装：

./autogen.sh
./configure --prefix=/usr/bin/valgrind
./make
./make install

最后测试是否成功：

./valgrind ls -l

三、Memcheck使用

1.所需的编译选项

1.用

-g

使目标文件保存调试信息(行号等)

2.用

-O0

或

-O1

优化选项，

-O0

最准确但速度慢,

-O1

可能不准确但速度快，通常效果也不错。

2.检测内存泄露

./valgrind --leak-check=full ./a.out

3.例子

test.c:

#include <stdio.h>
void func()
{
char *temp = new char[100];//memery leak
printf("i lose 100 bytes~\n");
}

int main()
{
func();
return 0;
}

gcc -g -o test test.c

用valgrind运行程序：

./valgrind --leak-check=full ./test

结果如下：

==25108== Memcheck, a memory error detector
==25108== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==25108== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==25108== Command: ./test
==25108==
==25108==
==25108== HEAP SUMMARY:
==25108==     in use at exit: 100 bytes in 1 blocks
==25108==   total heap usage: 1 allocs, 0 frees, 100 bytes allocated
==25108==
==25108== 100 bytes in 1 blocks are definitely lost in loss record 1 of 1
==25108==    at 0x40078C6: operator new[](unsigned int) (vg_replace_malloc.c:357)
==25108==    by 0x80484D5: func() (test.cc:5)
==25108==    by 0x80484F1: main (test.cc:11)
==25108==
==25108== LEAK SUMMARY:
==25108==    definitely lost: 100 bytes in 1 blocks
==25108==    indirectly lost: 0 bytes in 0 blocks
==25108==      possibly lost: 0 bytes in 0 blocks
==25108==    still reachable: 0 bytes in 0 blocks
==25108==         suppressed: 0 bytes in 0 blocks
==25108==
==25108== For counts of detected and suppressed errors, rerun with: -v
==25108== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 15 from 8)

从中可以发现是在func()中new操作导致的内存泄露。