http://www.jackxiang.com/index.php zh-cn http://www.jackxiang.com/post// jack <xdy108@126.com> Sat, 13 Aug 2011 09:01:42 +0000 http://www.jackxiang.com/post// Valgrind工具包包含多个工具，如Memcheck,Cachegrind,Helgrind, Callgrind，Massif。下面分别介绍个工具的作用：
Memcheck 工具主要检查下面的程序错误：
• 使用未初始化的内存 (Use of uninitialised memory)
• 使用已经释放了的内存 (Reading/writing memory after it has been free’d)
• 使用超过 malloc分配的内存空间(Reading/writing off the end of malloc’d blocks)
• 对堆栈的非法访问 (Reading/writing inappropriate areas on the stack)
• 申请的空间是否有释放 (Memory leaks – where pointers to malloc’d blocks are lost forever)
• malloc/free/new/delete申请和释放内存的匹配(Mismatched use of malloc/new/new [] vs free/delete/delete [])
• src和dst的重叠(Overlapping src and dst pointers in memcpy() and related functions)
Valgrind不检查静态分配数组的使用情况。
Valgrind占用了更多的内存--可达两倍于你程序的正常使用量。如果你用Valgrind来检测使用大量内存的程序就会遇到问题，它可能会用很长的时间来运行测试
2.1. 下载安装
http://www.valgrind.org
安装
./configure;make;make install
2.2. 编译程序
被检测程序加入 –g   -fno-inline 编译选项保留调试信息。

2.3. 内存泄露检测
$ valgrind --leak-check=full --show-reachable=yes --trace-children=yes    ./iquery   -f ../conf/se.conf_forum -t   ~/eragon/forum_thread_data/f.log -NT   -cache 0
其中--leak-check=full 指的是完全检查内存泄漏，--show-reachable=yes是显示内存泄漏的地点，--trace-children=yes是跟入子进程。当程序正常退出的时候valgrind自然会输出内存泄漏的信息。

来自: http://hi.baidu.com/benbendy/blog/item/905f7638a3233bfab211c709.html
参看：http://zyan.cc/post/419/

—————————————————试着调一个epoll的多进程测试小程序————————————————————
刚运行起来没有泄漏，多请求几次后再ctrl+C退出时，发现有泄漏情况了，如下所示：
[root@test multepoolserver]# valgrind --tool=memcheck --leak-check=full ./multipepollserver
[root@test multepoolserver]# valgrind --tool=memcheck --leak-check=full multipepollserver / valgrind: multipepollserver: command not found [root@test multepoolserver]# valgrind --tool=memcheck --leak-check=full multipepollserver valgrind: multipepollserver: command not found [root@test multepoolserver]# valgrind --tool=memcheck --leak-check=full multipepollserver valgrind: multipepollserver: command not found [root@test multepoolserver]# valgrind --tool=memcheck --leak-check=full ./multipepollserver ==24877== Memcheck, a memory error detector ==24877== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==24877== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info ==24877== Command: ./multipepollserver ==24877== ==24877== Conditional jump or move depends on uninitialised value(s) ==24877==    at 0x3C9A2436B0: vfprintf (in /lib64/libc-2.5.so) ==24877==    by 0x3C9A263B48: vsprintf (in /lib64/libc-2.5.so) ==24877==    by 0x4019A1: prename_setproctitle(char const*, ...) (multipepollserver.cpp:286) ==24877==    by 0x40298D: main (multipepollserver.cpp:481) ==24877== ==24877== Use of uninitialised value of size 8 ==24877==    at 0x4A08EA2: strlen (mc_replace_strmem.c:404) ==24877==    by 0x3C9A246B68: vfprintf (in /lib64/libc-2.5.so) ==24877==    by 0x3C9A263B48: vsprintf (in /lib64/libc-2.5.so) ==24877==    by 0x4019A1: prename_setproctitle(char const*, ...) (multipepollserver.cpp:286) ==24877==    by 0x40298D: main (multipepollserver.cpp:481) ==24877== ==24877== Use of uninitialised value of size 8 ==24877==    at 0x4A08EB4: strlen (mc_replace_strmem.c:404) ==24877==    by 0x3C9A246B68: vfprintf (in /lib64/libc-2.5.so) ==24877==    by 0x3C9A263B48: vsprintf (in /lib64/libc-2.5.so) ==24877==    by 0x4019A1: prename_setproctitle(char const*, ...) (multipepollserver.cpp:286) ==24877==    by 0x40298D: main (multipepollserver.cpp:481) ==24877== ==24877== Use of uninitialised value of size 8 ==24877==    at 0x3C9A26E256: _IO_default_xsputn (in /lib64/libc-2.5.so) ==24877==    by 0x3C9A246502: vfprintf (in /lib64/libc-2.5.so) ==24877==    by 0x3C9A263B48: vsprintf (in /lib64/libc-2.5.so) ==24877==    by 0x4019A1: prename_setproctitle(char const*, ...) (multipepollserver.cpp:286) ==24877==    by 0x40298D: main (multipepollserver.cpp:481) ==24877== parent process id 24877 ==24877== Warning: ignored attempt to set SIGKILL handler in sigaction(); ==24877==          the SIGKILL signal is uncatchable child process id 24878,parent id 24877 ==24878== Warning: ignored attempt to set SIGKILL handler in sigaction(); ==24878==          the SIGKILL signal is uncatchable 进入线程举旗：sync_additional_writing_worker... ==24878== Conditional jump or move depends on uninitialised value(s) ==24878==    at 0x3C9A2436B0: vfprintf (in /lib64/libc-2.5.so) ==24878==    by 0x3C9A263B48: vsprintf (in /lib64/libc-2.5.so) ==24878==    by 0x4019A1: prename_setproctitle(char const*, ...) (multipepollserver.cpp:286) ==24878==    by 0x402B93: main (multipepollserver.cpp:558) ==24878== thread id is 94632256,procees id is 24877,waiting for into while... ==24878== Warning: invalid file descriptor -1 in syscall close() ==24878== Syscall param epoll_ctl(event) points to uninitialised byte(s) ==24878==    at 0x3C9A2D3F9A: epoll_ctl (in /lib64/libc-2.5.so) ==24878==    by 0x401DAA: Process(int, int*) (multipepollserver.cpp:102) ==24878==    by 0x402BA0: main (multipepollserver.cpp:560) ==24878==  Address 0xfff000688 is on thread 1's stack 浏览器多请求几次，于是出现了 definitely lost，如下： ==24877== ==24877== HEAP SUMMARY: ==24877==     in use at exit: 1,901 bytes in 31 blocks ==24877==   total heap usage: 32 allocs, 1 frees, 2,469 bytes allocated ==24877== ==24878== ==24878== HEAP SUMMARY: ==24878==     in use at exit: 1,906 bytes in 60 blocks ==24878==   total heap usage: 61 allocs, 1 frees, 2,474 bytes allocated ==24878== ==24878== 293 (240 direct, 53 indirect) bytes in 1 blocks are definitely lost in loss record 2 of 4 ==24878==    at 0x4A072D0: malloc (vg_replace_malloc.c:291) ==24878==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24878==    by 0x402B80: main (multipepollserver.cpp:557) ==24878== ==24878== 1,613 (240 direct, 1,373 indirect) bytes in 1 blocks are definitely lost in loss record 4 of 4 ==24878==    at 0x4A072D0: malloc (vg_replace_malloc.c:291) ==24878==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24878==    by 0x40297A: main (multipepollserver.cpp:480) ==24878== ==24878== LEAK SUMMARY: ==24878==    definitely lost: 480 bytes in 2 blocks ==24878==    indirectly lost: 1,426 bytes in 58 blocks ==24878==      possibly lost: 0 bytes in 0 blocks ==24878==    still reachable: 0 bytes in 0 blocks ==24878==         suppressed: 0 bytes in 0 blocks ==24878== ==24878== For counts of detected and suppressed errors, rerun with: -v ==24878== Use --track-origins=yes to see where uninitialised values come from ==24878== ERROR SUMMARY: 41 errors from 8 contexts (suppressed: 4 from 4) ==24877== 288 bytes in 1 blocks are possibly lost in loss record 1 of 3 ==24877==    at 0x4A0652F: calloc (vg_replace_malloc.c:618) ==24877==    by 0x3C9920FEF2: _dl_allocate_tls (in /lib64/ld-2.5.so) ==24877==    by 0x3C9AE06C29: pthread_create@@GLIBC_2.2.5 (in /lib64/libpthread-2.5.so) ==24877==    by 0x402A36: main (multipepollserver.cpp:512) ==24877== ==24877== 1,613 (240 direct, 1,373 indirect) bytes in 1 blocks are definitely lost in loss record 3 of 3 ==24877==    at 0x4A072D0: malloc (vg_replace_malloc.c:291) ==24877==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24877==    by 0x40297A: main (multipepollserver.cpp:480) ==24877== ==24877== LEAK SUMMARY: ==24877==    definitely lost: 240 bytes in 1 blocks ==24877==    indirectly lost: 1,373 bytes in 29 blocks ==24877==      possibly lost: 288 bytes in 1 blocks ==24877==    still reachable: 0 bytes in 0 blocks ==24877==         suppressed: 0 bytes in 0 blocks ==24877== ==24877== For counts of detected and suppressed errors, rerun with: -v ==24877== Use --track-origins=yes to see where uninitialised values come from ==24877== ERROR SUMMARY: 21 errors from 6 contexts (suppressed: 4 from 4) [root@test multepoolserver]# ————————————————返回结果中的“definitely lost: 480 bytes in 2 blocks”表示发生内存泄漏————————————————— 重点性查一下,multipepollserver.cpp:261 行,main (multipepollserver.cpp:512)： ==24878==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24878==    by 0x402B80: main (multipepollserver.cpp:557) ==24878== ==24878== 1,613 (240 direct, 1,373 indirect) bytes in 1 blocks are definitely lost in loss record 4 of 4 ==24878==    at 0x4A072D0: malloc (vg_replace_malloc.c:291) ==24878==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24878==    by 0x40297A: main (multipepollserver.cpp:480) ==24878== ==24878== LEAK SUMMARY: ==24878==    definitely lost: 480 bytes in 2 blocks ==24877==    by 0x402A36: main (multipepollserver.cpp:512) ==24877== ==24877== 1,613 (240 direct, 1,373 indirect) bytes in 1 blocks are definitely lost in loss record 3 of 3 ==24877==    at 0x4A072D0: malloc (vg_replace_malloc.c:291) ==24877==    by 0x401AF4: prename_setproctitle_init(int, char**, char**) (multipepollserver.cpp:261) ==24877==    by 0x40297A: main (multipepollserver.cpp:480) ==24877== ==24877== LEAK SUMMARY: ==24877==    definitely lost: 240 bytes in 1 blocks

一查原因，两条遗漏：
for (i = 0; envp[i] != NULL; i++)                  
    environ[i] = strdup(envp[i]);//xstrdup(envp[i]);
environ[i] = NULL;
1.这个for没有把：environ[i] = NULL; 给括号进来，没有释放掉？不对：
strdup
(gdb) print *envp
$2 = 0x7fff72df6afa "HOSTNAME=test.local"
$4 = 0x7fff72df6ac8 "/home/xiangdong/multepoolserver/multipepollserver"
2.没有free掉char *：char * httpmut_prename_child_buf="worker process"; /* 原命令行参数:子进程名字。 */
prename_setproctitle("[httpmut: worker process] %s", httpmut_prename_child_buf);
free(httpmut_prename_child_buf);//这个得free掉。

==26827==    by 0x4029CA: main (multipepollserver.cpp:484)
(gdb) c
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x0000003c9a27272e in free () from /lib64/libc.so.6
(gdb) bt
#0  0x0000003c9a27272e in free () from /lib64/libc.so.6
#1  0x00000000004029e7 in main (argc=1, argv=0x7fff72df4e08, envp=0x7fff72df4e18) at multipepollserver.cpp:486


用ab.exe压力一下？
D:\wamp\bin\apache\apache2.2.22\bin\ab.exe -c 1000 -n 1000 http://t.jackxiang.com
会提示：[http://]hostname[:port]/path
D:\wamp\bin\apache\apache2.2.22\bin\ab.exe -c 1000 -n 1000 http://t.jackxiang.com/

C语言调指针可真是个小心活儿，还得有工具，有经验啊EOF。
]]> http://www.jackxiang.com/post//#blogcomment <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 http://www.jackxiang.com/post//#blogcomment