在编译安装完MySQL后，就可以使用gdb来跟踪mysql服务器的执行了。
gdb --args /usr/local/mysql/libexec/mysqld
(gdb) b mysql_select Breakpoint 1 at 0x8228b7d: file sql_select.cc, line 2315. (gdb) b my_net_read Breakpoint 2 at 0x81a13e4: file net_serv.cc, line 993. (gdb) run Starting program: /usr/local/mysql/libexec/mysqld [Thread debugging using libthread_db enabled] [New Thread 0xb7feeb70 (LWP 1373)] [Thread 0xb7feeb70 (LWP 1373) exited] [New Thread 0xb77edb70 (LWP 1374)] 110225 22:36:33 [Note] Event Scheduler: Loaded 0 events 110225 22:36:33 [Note] /usr/local/mysql/libexec/mysqld: ready for connections. Version: '5.1.34-debug' socket: '/tmp/mysql.sock' port: 3306 Source distribution
此时在登陆客户端，通过另外一个shelll运行mysql客户端
gdb会出现如下信息：
[New Thread 0xb77ccb70 (LWP 1410)] [Switching to Thread 0xb77ccb70 (LWP 1410)]
Breakpoint 2, my_net_read (net=0x85610bc) at net_serv.cc:993 993 if (!net->compress) (gdb)
表明设置断点成功。。。。