dmalloc用法快速入门

原文链接

常用内存泄露检测手段有

• 1 mtrace
• 2 memwatch
• 3 mpatrol
• 4 dmalloc
• 5 dbgmem
• 6 valgrind
• 7 Electric Fence

dmalloc是一个简单易用的C/C++内存leak检查工具，以一个运行库的方式发布。

dmalloc能够检查出直到程序运行结束还没有释放的内存，并且能够精确指出在
哪个源文件的第几行。

dmalloc 主页： http://dmalloc.com

支持的平台：AIX, BSD/OS, DG/UX, Free/Net/OpenBSD, GNU/Hurd, HPUX, Irix, Linux, MS-DOG, NeXT, OSF, SCO, Solaris, SunOS, Ultrix, Unixware, Windoze, and even Unicos on a Cray T3E

最新版本： 5.5.2

安装：下载 http://dmalloc.com/releases/dmalloc-5.5.2.tgz

1. tar zxvf dmalloc-5.5.2.tgz
2. cd dmalloc-5.5.2
3. ./configure
4. make
5. make install

设置环境变量：
对于 Bash, ksh, and zsh (http://www.zsh.org/), 在 `.bashrc', `.profile', or `.zshrc'
文件中加入一行 ( -b 参数表示针对Bash的输出):

function dmalloc { eval `command dmalloc -b $*`; }

然后重新登陆用户，或者执行: source ~/.bashrc 或 source ~/.profile

接下面执行:

1. dmalloc -l logfile -i 100 low

在源文件中添加下面的C代码：

#ifdef DMALLOC
#include "dmalloc.h"
#endif

编译使用的CFLAGS: -DDMALLOC -DDMALLOC_FUNC_CHECK

如： gcc -DDMALLOC -DDMALLOC_FUNC_CHECK dm_test.c

执行:
./a.out

运行上面的命令会在当前目录下生成 logfile文件，查看logfile的内容如下：

cat logfile

1. 1214894489: 2: Dmalloc version '5.5.2' from 'http://dmalloc.com/'
2. 1214894489: 2: flags = 0x4e48503, logfile 'logfile'
3. 1214894489: 2: interval = 100, addr = 0, seen # = 0, limit = 0
4. 1214894489: 2: starting time = 1214894489
5. 1214894489: 2: process pid = 9560
6. 1214894489: 2: Dumping Chunk Statistics:
7. 1214894489: 2: basic-block 4096 bytes, alignment 8 bytes
8. 1214894489: 2: heap address range: 0xb8020000 to 0xb8029000, 36864 bytes
9. 1214894489: 2:     user blocks: 1 blocks, 4043 bytes (10%)
10. 1214894489: 2:    admin blocks: 8 blocks, 32768 bytes (89%)
11. 1214894489: 2:    total blocks: 9 blocks, 36864 bytes
12. 1214894489: 2: heap checked 1
13. 1214894489: 2: alloc calls: malloc 2, calloc 0, realloc 0, free 0
14. 1214894489: 2: alloc calls: recalloc 0, memalign 0, valloc 0
15. 1214894489: 2: alloc calls: new 0, delete 0
16. 1214894489: 2:   current memory in use: 11 bytes (2 pnts)
17. 1214894489: 2:  total memory allocated: 11 bytes (2 pnts)
18. 1214894489: 2:  max in use at one time: 11 bytes (2 pnts)
19. 1214894489: 2: max alloced with 1 call: 6 bytes
20. 1214894489: 2: max unused memory space: 53 bytes (82%)
21. 1214894489: 2: top 10 allocations:
22. 1214894489: 2:  total-size  count in-use-size  count  source
23. 1214894489: 2:           6      1           6      1  dm_test.c:71
24. 1214894489: 2:           5      1           5      1  dm_test.c:69
25. 1214894489: 2:          11      2          11      2  Total of 2
26. 1214894489: 2: Dumping Not-Freed Pointers Changed Since Start:
27. 1214894489: 2:  not freed: '0xb8028fc8|s1' (6 bytes) from 'dm_test.c:71'
28. 1214894489: 2:  not freed: '0xb8028fe8|s1' (5 bytes) from 'dm_test.c:69'
29. 1214894489: 2:  total-size  count  source
30. 1214894489: 2:           6      1  dm_test.c:71
31. 1214894489: 2:           5      1  dm_test.c:69
32. 1214894489: 2:          11      2  Total of 2
33. 1214894489: 2: ending time = 1214894489, elapsed since start = 0:00:00

那么，哪个地方的内存leak就一目了然了。

//====== dm_test.c 源代码 =============

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
4.  
5. #ifdef DMALLOC
6. #include <dmalloc.h>
7. #endif
8.  
9. int main(int argc, char **argv)
10. {
11.    
12.     char *str;
13.  
14.     str = malloc(5);
15.  
16.     str = malloc(6);
17.    
18.     return 0;
19. }