GDB 调试 Mysql 实战(二)GDB 调试打印
来源:SegmentFault
时间:2023-01-22 19:23:16 191浏览 收藏
哈喽!今天心血来潮给大家带来了《GDB 调试 Mysql 实战(二)GDB 调试打印》,想必大家应该对数据库都不陌生吧,那么阅读本文就都不会很困难,以下内容主要涉及到MySQL,若是你正在学习数据库,千万别错过这篇文章~希望能帮助到你!
背景
在 https://mengkang.net/1328.html 实验中,我们通过
[root@localhost ~]# ps -ef|grep mysql root 3739 1 0 09:36 ? 00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/localhost.localdomain.pid mysql 3894 3739 0 09:36 ? 00:00:01 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/var/lib/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/var/log/mariadb/mariadb.log --pid-file=/var/lib/mysql/localhost.localdomain.pid --socket=/var/lib/mysql/mysql.sock root 3956 3940 0 09:48 pts/1 00:00:00 mysql -uroot -px xxxx root 4002 3985 0 10:11 pts/2 00:00:00 grep --color=auto mysql
启动 gdb
[root@localhost ~]# gdb GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-114.el7 Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http:> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". For bug reporting instructions, please see: <http:></http:>.</http:>
attach pid
(gdb) attach 3894
设置断点
(gdb) b trace_tmp_table Breakpoint 1 at 0x15e1eeb: file /root/newdb/mysql-server/sql/sql_tmp_table.cc, line 2300.
或者
(gdb) b /root/newdb/mysql-server/sql/sql_tmp_table.cc:2306 Breakpoint 1 at 0x15e1f8e: file /root/newdb/mysql-server/sql/sql_tmp_table.cc, line 2306.
客户端连接
[root@localhost ~]# mysql -uroot -p123456 test mysql: [Warning] Using a password on the command line interface can be insecure.
阻塞中
打印 backtrace
(gdb) bt #0 0x00007effcf4ec20d in poll () from /lib64/libc.so.6 #1 0x0000000001667759 in Mysqld_socket_listener::listen_for_connection_event (this=0x42e6360) at /root/newdb/mysql-server/sql/conn_handler/socket_connection.cc:852 #2 0x0000000000eb14fc in Connection_acceptor<mysqld_socket_listener>::connection_event_loop (this=0x42ea0a0) at /root/newdb/mysql-server/sql/conn_handler/connection_acceptor.h:66 #3 0x0000000000ea8f7a in mysqld_main (argc=12, argv=0x41a60e8) at /root/newdb/mysql-server/sql/mysqld.cc:5149 #4 0x0000000000ea00ed in main (argc=8, argv=0x7ffece17c7e8) at /root/newdb/mysql-server/sql/main.cc:25</mysqld_socket_listener>
因为主进程在 poll 一直在等待客户端连接请求。
执行 continue
(gdb) c Continuing.
此时,mysql 客户端则进入 mysql 命令行界面
[root@localhost ~]# mysql -uroot -p123456 test mysql: [Warning] Using a password on the command line interface can be insecure. Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 Server version: 5.7.25-debug Source distribution Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>
客户端执行查询
SET optimizer_trace='enabled=on'; select aid,sum(pv) as num from article_rank force index(idx_day_aid_pv) where day>20181223 group by aid order by num desc LIMIT 10;
查看断点处信息
[Switching to Thread 0x7f7f20145700 (LWP 4392)] Breakpoint 1, trace_tmp_table (trace=0x7eff94003088, table=0x7eff94937200) at /root/newdb/mysql-server/sql/sql_tmp_table.cc:2306 warning: Source file is more recent than executable. 2306 trace_tmp.add("row_length",table->s->reclength). (gdb) p table->s->reclength $1 = 20 (gdb) p table->s->fields $2 = 2 (gdb) p (*(table->field+0))->field_name $3 = 0x7eff94010b0c "aid" (gdb) p (*(table->field+1))->field_name $4 = 0x7eff94007518 "num" (gdb) p (*(table->field+0))->row_pack_length() $5 = 4 (gdb) p (*(table->field+1))->row_pack_length() $6 = 15 (gdb) p (*(table->field+0))->type() $7 = MYSQL_TYPE_LONG (gdb) p (*(table->field+1))->type() $8 = MYSQL_TYPE_NEWDECIMAL (gdb)
总结
原来和
[root@localhost ~]# gdb GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-114.el7 Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http:> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". For bug reporting instructions, please see: <http:></http:>. (gdb) attach 3894 Attaching to process 3894 Reading symbols from /usr/local/mysql/bin/mysqld...done. Reading symbols from /lib64/libpthread.so.0...(no debugging symbols found)...done. [New LWP 4392] [New LWP 4368] [New LWP 4367] [New LWP 4366] [New LWP 4365] [New LWP 4364] [New LWP 4363] [New LWP 4362] [New LWP 4361] [New LWP 4360] [New LWP 4359] [New LWP 4358] [New LWP 4357] [New LWP 4356] [New LWP 4355] [New LWP 4353] [New LWP 4352] [New LWP 4351] [New LWP 4350] [New LWP 4349] [New LWP 4348] [New LWP 4347] [New LWP 4346] [New LWP 4345] [New LWP 4344] [New LWP 4343] [New LWP 4342] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". Loaded symbols for /lib64/libpthread.so.0 Reading symbols from /lib64/libcrypt.so.1...(no debugging symbols found)...done. Loaded symbols for /lib64/libcrypt.so.1 Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/libdl.so.2 Reading symbols from /lib64/librt.so.1...(no debugging symbols found)...done. Loaded symbols for /lib64/librt.so.1 Reading symbols from /lib64/libstdc++.so.6...(no debugging symbols found)...done. Loaded symbols for /lib64/libstdc++.so.6 Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done. Loaded symbols for /lib64/libm.so.6 Reading symbols from /lib64/libgcc_s.so.1...(no debugging symbols found)...done. Loaded symbols for /lib64/libgcc_s.so.1 Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done. Loaded symbols for /lib64/libc.so.6 Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/ld-linux-x86-64.so.2 Reading symbols from /lib64/libfreebl3.so...Reading symbols from /lib64/libfreebl3.so...(no debugging symbols found)...done. (no debugging symbols found)...done. Loaded symbols for /lib64/libfreebl3.so Reading symbols from /lib64/libnss_files.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/libnss_files.so.2 0x00007f7f2c32620d in poll () from /lib64/libc.so.6 Missing separate debuginfos, use: debuginfo-install glibc-2.17-260.el7.x86_64 libgcc-4.8.5-36.el7.x86_64 libstdc++-4.8.5-36.el7.x86_64 nss-softokn-freebl-3.36.0-5.el7_5.x86_64 (gdb) b /root/newdb/mysql-server/sql/sql_tmp_table.cc:2306 Breakpoint 1 at 0x15e1f8e: file /root/newdb/mysql-server/sql/sql_tmp_table.cc, line 2306. (gdb) bt #0 0x00007f7f2c32620d in poll () from /lib64/libc.so.6 #1 0x0000000001667759 in Mysqld_socket_listener::listen_for_connection_event (this=0x3841360) at /root/newdb/mysql-server/sql/conn_handler/socket_connection.cc:852 #2 0x0000000000eb14fc in Connection_acceptor<mysqld_socket_listener>::connection_event_loop (this=0x38450a0) at /root/newdb/mysql-server/sql/conn_handler/connection_acceptor.h:66 #3 0x0000000000ea8f7a in mysqld_main (argc=12, argv=0x37010e8) at /root/newdb/mysql-server/sql/mysqld.cc:5149 #4 0x0000000000ea00ed in main (argc=8, argv=0x7ffdaf5bc2e8) at /root/newdb/mysql-server/sql/main.cc:25 (gdb) c Continuing. [Switching to Thread 0x7f7f20145700 (LWP 4392)] Breakpoint 1, trace_tmp_table (trace=0x7f7ef8016b18, table=0x7f7ef8937380) at /root/newdb/mysql-server/sql/sql_tmp_table.cc:2306 warning: Source file is more recent than executable. 2306 trace_tmp.add("row_length",table->s->reclength). (gdb) p table->s->reclength $1 = 20 (gdb) p table->s->fields $2 = 2 (gdb) p (*(table->field+0))->field_name $3 = 0x7eff94010b0c "aid" (gdb) p (*(table->field+1))->field_name $4 = 0x7eff94007518 "num" (gdb) p (*(table->field+0))->row_pack_length() $5 = 4 (gdb) p (*(table->field+1))->row_pack_length() $6 = 15 (gdb) p (*(table->field+0))->type() $7 = MYSQL_TYPE_LONG (gdb) p (*(table->field+1))->type() $8 = MYSQL_TYPE_NEWDECIMAL (gdb)</mysqld_socket_listener></http:>
今天关于《GDB 调试 Mysql 实战(二)GDB 调试打印》的内容就介绍到这里了,是不是学起来一目了然!想要了解更多关于mysql的内容请关注golang学习网公众号!
声明:本文转载于:SegmentFault 如有侵犯,请联系study_golang@163.com删除
相关阅读
更多>
-
499 收藏
-
244 收藏
-
235 收藏
-
157 收藏
-
101 收藏
最新阅读
更多>
-
278 收藏
-
126 收藏
-
414 收藏
-
320 收藏
-
247 收藏
-
149 收藏
-
392 收藏
-
268 收藏
-
162 收藏
-
349 收藏
-
363 收藏
-
345 收藏
课程推荐
更多>
-
- 前端进阶之JavaScript设计模式
- 设计模式是开发人员在软件开发过程中面临一般问题时的解决方案,代表了最佳的实践。本课程的主打内容包括JS常见设计模式以及具体应用场景,打造一站式知识长龙服务,适合有JS基础的同学学习。
- 立即学习 543次学习
-
- GO语言核心编程课程
- 本课程采用真实案例,全面具体可落地,从理论到实践,一步一步将GO核心编程技术、编程思想、底层实现融会贯通,使学习者贴近时代脉搏,做IT互联网时代的弄潮儿。
- 立即学习 514次学习
-
- 简单聊聊mysql8与网络通信
- 如有问题加微信:Le-studyg;在课程中,我们将首先介绍MySQL8的新特性,包括性能优化、安全增强、新数据类型等,帮助学生快速熟悉MySQL8的最新功能。接着,我们将深入解析MySQL的网络通信机制,包括协议、连接管理、数据传输等,让
- 立即学习 499次学习
-
- JavaScript正则表达式基础与实战
- 在任何一门编程语言中,正则表达式,都是一项重要的知识,它提供了高效的字符串匹配与捕获机制,可以极大的简化程序设计。
- 立即学习 487次学习
-
- 从零制作响应式网站—Grid布局
- 本系列教程将展示从零制作一个假想的网络科技公司官网,分为导航,轮播,关于我们,成功案例,服务流程,团队介绍,数据部分,公司动态,底部信息等内容区块。网站整体采用CSSGrid布局,支持响应式,有流畅过渡和展现动画。
- 立即学习 484次学习