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MySQL连接数据库函数内存泄露解决方案

WBOY
풀어 주다: 2016-06-07 17:04:18
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Linux 下使用C操作MySQL数据库时写个测试程序 int main(void) { MYSQL m_mysql; mysql_init(m_mysql);

Linux 下使用C操作MySQL数据库时写个测试程序

  • {  
  •     MYSQL m_mysql;  
  •     mysql_init(&m_mysql);  
  •       
  •       
  •     if(mysql_real_connect(&m_mysql,pLocalhost,pUser,pPass,pDB,0,NULL,0) == NULL) 
  • //mysql_connect() 连接一个MySQL服务器。该函数不推荐;使用mysql_real_connect()代替。
  •         cout"connect failed"
  •     else  
  •         cout"connect success"
  •        
  •     mysql_close(&m_mysql);      
  • 编译后使用valgrind检测内存泄露

    [root@localhost string]# valgrind --tool=memcheck --leak-check=full ./mysql 
    ==10352== Memcheck, a memory error detector
    ==10352== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
    ==10352== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
    ==10352== Command: ./mysql
    ==10352== 
    connect success
    ==10352== 
    ==10352== HEAP SUMMARY:
    ==10352==     in use at exit: 61,336 bytes in 16 blocks
    ==10352==   total heap usage: 118 allocs, 102 frees, 115,929 bytes allocated
    ==10352== 
    ==10352== 24,528 bytes in 6 blocks are possibly lost in loss record 4 of 5
    ==10352==    at 0x4005903: malloc (vg_replace_malloc.c:195)
    ==10352==    by 0x30DD75: my_once_alloc (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30E59C: ??? (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30EF96: ??? (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30F111: get_charset_by_csname (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x32C3D2: mysql_init_character_set (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x32DABB: mysql_real_connect (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x8048A76: main (str.cpp:32)
    ==10352== 
    ==10352== 28,616 bytes in 7 blocks are possibly lost in loss record 5 of 5
    ==10352==    at 0x4005903: malloc (vg_replace_malloc.c:195)
    ==10352==    by 0x30DD75: my_once_alloc (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30E57A: ??? (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30EF96: ??? (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x30F111: get_charset_by_csname (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x32C3D2: mysql_init_character_set (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x32DABB: mysql_real_connect (in /usr/lib/mysql/libmysqlclient.so.15.0.0)
    ==10352==    by 0x8048A76: main (str.cpp:32)
    ==10352== 
    ==10352== LEAK SUMMARY:
    ==10352==    definitely lost: 0 bytes in 0 blocks
    ==10352==    indirectly lost: 0 bytes in 0 blocks
    ==10352==      possibly lost: 53,144 bytes in 13 blocks
    ==10352==    still reachable: 8,192 bytes in 3 blocks
    ==10352==         suppressed: 0 bytes in 0 blocks
    ==10352== Reachable blocks (those to which a pointer was found) are not shown.
    ==10352== To see them, rerun with: --leak-check=full --show-reachable=yes
    ==10352== 
    ==10352== For counts of detected and suppressed errors, rerun with: -v
    ==10352== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 3

    2、解决措施

    简单的说是在断开数据库连接后使用

    mysql_library_end()

    关闭MYSQL 使用的库即在mysql_close(。。。)后添加mysql_library_end()就ok了

    再添加一句,在使用mysql API之前最好是调用mysql_library_init(。。。。)

    linux

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