Linux C/C++ 内存泄漏检测工具:Valgrind

Linux C/C++ 内存泄漏检测工具:Valgrind

2015-02-05 作者: giser 浏览: 4138 次

摘要: Valgrind是一款Linux下(支持 x86、x86_64和ppc32)程序的内存调试工具,它可以对编译后的二进制程序进行内存使用监测(C语言中的malloc和free,以及C++中的new和delete),找出内存泄漏问题。 Valgrind 中包含的 ...

Valgrind是一款Linux下(支持 x86、x86_64和ppc32)程序的内存调试工具,它可以对编译后的二进制程序进行内存使用监测(C语言中的malloc和free,以及C++中的new和delete),找出内存泄漏问题。 Valgrind 中包含的 Memcheck 工具可以检查以下的程序错误:

  • 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)

重复free

  • 1、编译安装 Valgrind:

    wget http://valgrind.org/downloads/valgrind-3.4.1.tar.bz2 
    tar xvf valgrind-3.4.1.tar.bz2 
    cd valgrind-3.4.1/
    ./configure --prefix=/usr/local/webserver/valgrind 
    make 
    make install
    

  • 2、使用示例:对“ls”程序进程检查,返回结果中的“definitely lost: 0 bytes in 0 blocks.”表示没有内存泄漏。

    [root@xoyo42 /]# /usr/local/webserver/valgrind/bin/valgrind --tool=memcheck
    --leak-check=full ls / 
    ==1157== Memcheck, a memory error detector. 
    ==1157== Copyright (C) 2002-2008, and GNU GPL'd, by Julian Seward et al. 
    ==1157== Using LibVEX rev 1884, a library for dynamic binary translation. 
    ==1157== Copyright (C) 2004-2008, and GNU GPL'd, by OpenWorks LLP. 
    ==1157== Using valgrind-3.4.1,a dynamic binary instrumentation framework. 
    ==1157== Copyright (C) 2000-2008, and GNU GPL'd, by Julian Seward et al. 
    ==1157== For more details, rerun with: -v 
    ==1157== 
    bin data0 dev home lib64 media mnt opt root selinux sys tcsql.db.idx.pkey.dec 
    ttserver.pid var boot data1 etc lib lost+found misc net proc sbin srv tcsql.db tmp usr 
    ==1157== 
    ==1157== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 5 from 1) 
    ==1157== malloc/free: in use at exit: 28,471 bytes in 36 blocks. 
    ==1157== malloc/free: 166 allocs, 130 frees, 51,377 bytes allocated. 
    ==1157== For counts of detected errors, rerun with: -v 
    ==1157== searching for pointers to 36 not-freed blocks. ==1157== checked 174,640 bytes.
    ==1157== 
    ==1157== LEAK SUMMARY: 
    ==1157== definitely lost: 0 bytes in 0 blocks.
    ==1157== possibly lost: 0 bytes in 0 blocks. 
    ==1157== still reachable: 28,471
    bytes in 36 blocks. 
    ==1157== suppressed: 0 bytes in 0 blocks.
    ==1157==Reachable blocks (those to which a pointer was found) are not shown. 
    ==1157==To see them, rerun with: --leak-check=full --show-reachable=yes
    

3、使用示例:对一个使用libevent库编写的“httptest”程序进程检查,返回结果中的“definitely lost: 255 bytes in 5 blocks.”表示发生内存泄漏。

[root@xoyo42 tcsql-0.1]#/usr/local/webserver/valgrind/bin/valgrind 
--tool=memcheck --leak-check=full./httptest 
==1274== Memcheck, a memory error detector. 
==1274== Copyright (C)2002-2008, and GNU GPL'd, by Julian Seward et al. 
==1274== Using LibVEX rev 1884, a library for dynamic binary translation. 
==1274== Copyright (C)2004-2008, and GNU GPL'd, by OpenWorks LLP. 
==1274== Using valgrind-3.4.1, adynamic binary instrumentation framework. 
==1274== Copyright (C) 2000-2008,and GNU GPL'd, by Julian Seward et al. 
==1274== For more details, rerun with: -v 
==1274== 
==1274== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 1005 from 2) 
==1274== malloc/free: in use at exit: 402,291 bytes in 74 blocks.
==1274== malloc/free: 15,939 allocs, 15,865 frees, 6,281,523 bytes allocated.
==1274== For counts of detected errors, rerun with: -v 
==1274== searching for pointers to 74 not-freed blocks. 
==1274== checked 682,468,160 bytes. 
==1274==
==1274== 255 bytes in 5 blocks are definitely lost in loss record 17 of 32
==1274== at 0x4A05FBB: malloc (vg_replace_malloc.c:207) 
==1274== by 0x3C1D809BC6: evhttp_decode_uri (http.c:2105) 
==1274== by 0x401C75:tcsql_handler (in /data0/tcsql/cankao/tcsql-0.1/tcsql) 
==1274== by 0x3C1D80C88F: evhttp_get_body (http.c:1582) 
==1274== by 0x3C1D8065F7: event_base_loop (event.c:392) 
==1274== by 0x403E2F: main (in /data0/tcsql/cankao/tcsql-0.1/tcsql) 
==1274== 
==1274== LEAK SUMMARY: 
==1274== definitely lost: 255 bytes in 5 blocks. 
==1274== possibly lost: 0 bytes in 0 blocks. 
==1274== still reachable: 402,036 bytes in 69 blocks. 
==1274== suppressed: 0 bytes in 0 blocks. 
==1274== Reachable blocks (those to which a pointer was found) are not shown. 
==1274== To see them, rerun with: --leak-check=full --show-reachable=yes 

检查httptest程序,发现有一处“char *decode_uri = evhttp_decode_uri(evhttp_request_uri(req));”中的“decode_uri”没有被free,再程序处理完成后加上“free(decode_uri);”后,再使用Valgrind检查,结果已经是“definitely lost: 0 bytes in 0 blocks.”。

Gentoo下安装的问题 在Gentoo下安装完成后,发现有下面问题:

Valgrind will not work on ppc, ppc64 or amd64 if glibc does not have debug symbols (see
https://bugs.gentoo.org/show_bug.cgi?id=214065 and http://bugs.gentoo.org/show_bug.cgi?id=274771). To fix this you can add splitdebug to FEATURES in make.conf and remerge glibc. 

因此,需要针对上面的提示进行相应的处理。

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