打印程序動態分配內存的信息

例子

#include <stdio.h>
#include <malloc.h>

int main(void)
{
        char *p[10];
        int i = 0;

        for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
        {
                p[i] = malloc(100000);
        }
        return 0;
}

技巧

用gdb調試程序時，可以用下面的自定義命令，打印程序動態分配內存的信息：

define mallocinfo
  set $__f = fopen("/dev/tty", "w")
  call malloc_info(0, $__f)
  call fclose($__f)
end

以上面程序為例：

Temporary breakpoint 5, main () at a.c:7
7               int i = 0;
(gdb) mallocinfo 
<malloc version="1">
<heap nr="0">
<sizes>
</sizes>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="135168"/>
<system type="max" size="135168"/>
<aspace type="total" size="135168"/>
<aspace type="mprotect" size="135168"/>
</heap>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="135168"/>
<system type="max" size="135168"/>
<aspace type="total" size="135168"/>
<aspace type="mprotect" size="135168"/>
</malloc>
$20 = 0
$21 = 0
(gdb) n
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) mallocinfo 
<malloc version="1">
<heap nr="0">
<sizes>
</sizes>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="532480"/>
<system type="max" size="532480"/>
<aspace type="total" size="532480"/>
<aspace type="mprotect" size="532480"/>
</heap>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="532480"/>
<system type="max" size="532480"/>
<aspace type="total" size="532480"/>
<aspace type="mprotect" size="532480"/>
</malloc>
$22 = 0
$23 = 0
(gdb) n
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) 
11                      p[i] = malloc(100000);
(gdb) 
9               for (i = 0; i < sizeof(p)/sizeof(p[0]); i++)
(gdb) mallocinfo 
<malloc version="1">
<heap nr="0">
<sizes>
</sizes>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="1134592"/>
<system type="max" size="1134592"/>
<aspace type="total" size="1134592"/>
<aspace type="mprotect" size="1134592"/>
</heap>
<total type="fast" count="0" size="0"/>
<total type="rest" count="0" size="0"/>
<system type="current" size="1134592"/>
<system type="max" size="1134592"/>
<aspace type="total" size="1134592"/>
<aspace type="mprotect" size="1134592"/>
</malloc>
$24 = 0
$25 = 0

可以看到gdb輸出了動態分配內存的變化信息。
參見stackoverflow.

貢獻者

nanxiao