为解决Mysql数据库单点问题，实现两台MySQL数据库互为主备，双向replication。当一Master出现问题，则将Slave切换为Master继续工作.

环境说明

系统版本：CentOS Linux release 7.6.1810 (Core)

MySQL版本：mysql  Ver 14.14 Distrib 5.7.27

keepalived版本：Keepalived v1.2.13

序号 　　  服务器IP 　　　　用途

1 　　　　192.168.158.10    Master
2 　　　　192.168.158.20    Slave
3 　　　　192.168.158.30    VIP

一、MySQL互为主从配置

1.> 两台安装相同版本的MySQL数据库.
2.> 主备机NTP时钟同步
3.> 双机互信配置ssh免密认证
4.> 数据库配置(Master的配置和Slave的配置server-id不能一致,别的都可以一样)
4.1> 修改Master主机上MySQL数据库的配置文件，然后新启动MySQL

  1. #vim /ect/my.cnf
  2. [mysqld]
  3. log-bin=mysql-bin
  4. server-id=
  5. expire_logs_days =
  6. datadir=/var/lib/mysql
  7. socket=/var/lib/mysql/mysql.sock
  8. symbolic-links=
  9. log-error=/var/log/mysqld.log
  10. pid-file=/var/run/mysqld/mysqld.pid
  11. validate_password=off         #关闭密码安全策略
  12. default_password_lifetime=     #设置密码不过期
  13. log_bin=/var/log/mysql/mysql-bin

4.2> 修改Slave主机上MySQL数据库的配置文件，然后新启动MySQL

  1. #vim /ect/my.cnf
  2.  
  3. [mysqld]
  4. log-bin=mysql-bin
  5. server-id=
  6. expire_logs_days =
  7. datadir=/var/lib/mysql
  8. socket=/var/lib/mysql/mysql.sock
  9. symbolic-links=
  10. log-error=/var/log/mysqld.log
  11. pid-file=/var/run/mysqld/mysqld.pid
  12. validate_password=off
  13. default_password_lifetime=
  14. log_bin=/var/log/mysql/mysql-bin

5.> 启动MySQL服务

  1. # systemctl start mysqld

6.> 查询相关状态，以Master主机为例，如下

  1. mysql> show master status;
  2. +------------------+----------+--------------+------------------+-------------------+
  3. | File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
  4. +------------------+----------+--------------+------------------+-------------------+
  5. | mysql-bin. |       |              |                  |                   |
  6. +------------------+----------+--------------+------------------+-------------------+
  7.  row in set (0.00 sec)

7.> 创建复制账号并同步
7.1> 在Master库和Slave库分别执行，创建数据同步复制账号.

  1. mysql> GRANT REPLICATION SLAVE,REPLICATION CLIENT ON *.* TO replication@'%' IDENTIFIED BY 'replication';
  2. mysql> flush  privileges;

7.2> 7.2> 在Master主机上,执行同步操作(注意master_host参数主备机相互指向),如下：

  1. mysql> change master to master_host='192.168.158.20',master_port=,master_user='replication',master_password='replication',master_log_file='mysql-bin.000001',master_log_pos=;
  2. mysql> start slave;

7.3> 在Slave主机上,执行同步操作(注意master_host参数主备机相互指向),如下：

  1. mysql> change master to master_host='192.168.158.10',master_port=,master_user='replication',master_password='replication',master_log_file='mysql-bin.000001',master_log_pos=;
  2. mysql> start slave;

7.4> 在Master、Slave主机上，查询同步状态“show slave status\G”，检查结果中Slave_IO_Running: Yes和Slave_SQL_Running: Yes，否则有异常。

8.> 配置密文命令访问(两台主机都配置)
Mysql数据库使用mysql或mysqldump等相关命令时，需要在命令行界面输入密码，当使用脚本时，在脚本里填写密码显然不太安全，因此可以设置Mysql的密文文件。

  1. # mysql_config_editor set --login-path=local --user=root --port= --password
  2. # mysql_config_editor print --all

9.> 创建切换脚本

切换脚本规划，如本次是mysql切换，因此在该目录下创建mysql目录,将所有切换脚本放在/home/mysql目录下,本次相关脚本说明如下：

进入/home/mysql目录，如下文件：

Logs   　　       //存储日志的文件目录

mybackup.sh   //清空slave配置，重新获取远程日志文件及Pos,并开启同步

mycheck.sh     //检查mysql运行状态，如果运行正常，退出。如果运行不正常调用pkill keepalived

mymaster.sh    //先判断同步复制是否执行完成，如果未执行完成等待1分钟后，停止同步（stop slave;），并且记录切换后的日志和pos

.mysqlenv       //脚本运行环境文件

mystop.sh       //设置参数保证数据不丢失，最后检查看是否还有写操作，最后1分钟退出

syncposfile     //每次切换后，Master最后一次File值和Position值。

10.环境文件

10.1> Master主机端的环境文件

  1. [root@localhost mysql]# vim .mysqlenv
  2.  
  3. MYSQL=/usr/bin/mysql
  4. MYSQL_CMD="--login-path=local"
  5. #远端主机的IP地址
  6. REMOTE_IP=192.168.158.20
  7. export mysql="$MYSQL $MYSQL_CMD "

10.2> Slave主机端的环境文件

  1. [root@localhost mysql]# vim .mysqlenv
  2. MYSQL=/usr/bin/mysql
  3. MYSQL_CMD="--login-path=local"
  4. #远端主机的IP地址
  5. REMOTE_IP=192.168.158.10
  6. export mysql="$MYSQL $MYSQL_CMD"

11.> 服务检查脚本

11.1> mycheck.sh

  1. [root@localhost mysql]# vim mycheck.sh
  2. #!/bin/sh
  3.  
  4. ##################################################
  5. #File Name  : mycheck.sh
  6. #Description: mysql is working MYSQL_OK is
  7. #             mysql is down MYSQL_OK is
  8. ##################################################
  9.  
  10. BASEPATH=/home/mysql
  11. LOGSPATH=$BASEPATH/logs
  12. source $BASEPATH/.mysqlenv
  13.  
  14. CHECK_TIME=
  15. MYSQL_OK=
  16. ##################################################################
  17. function check_mysql_helth (){
  18.   $mysql -e "show status;" >/dev/null >&
  19.   if [ $? ==  ]
  20.   then
  21.     MYSQL_OK=
  22.   else
  23.     MYSQL_OK=
  24.     #systemctl status keepalived
  25.  fi
  26.  return $MYSQL_OK
  27. }
  28.  
  29. #check_mysql_helth
  30. while [ $CHECK_TIME -ne  ] #不等于
  31. do
  32.     let "CHECK_TIME -= 1"
  33.     check_mysql_helth
  34.     if [ $MYSQL_OK =  ] ; then
  35.     CHECK_TIME=
  36.     echo "$(date "+%Y-%m-%d %H:%M:%S") The scripts mycheck.sh is running ..." >> $LOGSPATH/mysql_switch.log
  37.     exit
  38.     fi
  39.     if [ $MYSQL_OK -eq  ] && [ $CHECK_TIME -eq  ] #等于
  40.     then
  41.     systemctl stop keepalived
  42.     echo "$(date "+%Y-%m-%d %H:%M:%S") The mycheck.sh, mysql is down, after switch..." >> $LOGSPATH/mysql_switch.log
  43.     exit
  44.     fi
  45.     sleep 　　
  46. done
  47. [root@localhost mysql]#

11.2> 切换脚本

  1. [root@localhost mysql]# vim mymaster.sh
  2. #!/bin/sh
  3.  
  4. ##################################################
  5. #File Name  : mymaster.sh
  6. #Description: First determine whether synchronous
  7. #             replication is performed, and if no
  8. #             execution is completed, wait for
  9. #             minutes. Log logs and POS after
  10. #             switching, and record files synchronously.
  11. ##################################################
  12.  
  13. BASEPATH=/home/mysql
  14. LOGSPATH=$BASEPATH/logs
  15. source $BASEPATH/.mysqlenv
  16.  
  17. $mysql -e "show slave status\G" > $LOGSPATH/mysqlslave.states
  18. Master_Log_File=`cat $LOGSPATH/mysqlslave.states | grep -w Master_Log_File | awk -F": " '{print $2}'`
  19. Relay_Master_Log_File=`cat $LOGSPATH/mysqlslave.states | grep -w Relay_Master_Log_File | awk -F": " '{print $2}'`
  20. Read_Master_Log_Pos=`cat $LOGSPATH/mysqlslave.states | grep -w Read_Master_Log_Pos | awk -F": " '{print $2}'`
  21. Exec_Master_Log_Pos=`cat $LOGSPATH/mysqlslave.states | grep -w Exec_Master_Log_Pos | awk -F": " '{print $2}'`
  22. i=
  23.  
  24. while true
  25. do
  26.     if [ $Master_Log_File = $Relay_Master_Log_File ] && [ $Read_Master_Log_Pos -eq $Exec_Master_Log_Pos ];then
  27.         echo "$(date "+%Y-%m-%d %H:%M:%S") The mymaster.sh, slave sync ok... " >> $LOGSPATH/mysql_switch.log
  28.         break
  29.     else
  30.         sleep
  31.         if [ $i -gt  ];then
  32.             break
  33.         fi
  34.         continue
  35.         let i++
  36.     fi
  37. done
  38.  
  39. $mysql -e "stop slave;"
  40. $mysql -e "set global innodb_support_xa=0;"
  41. $mysql -e "set global sync_binlog=0;"
  42. $mysql -e "set global innodb_flush_log_at_trx_commit=0;"
  43. $mysql -e "flush logs;GRANT ALL PRIVILEGES ON *.* TO 'replication'@'%' IDENTIFIED BY 'replication';flush privileges;"
  44. $mysql -e "show master status;" > $LOGSPATH/master_status_$(date "+%y%m%d-%H%M").txt
  45.  
  46. # sync pos file
  47. /usr/bin/scp $LOGSPATH/master_status_$(date "+%y%m%d-%H%M").txt root@$REMOTE_IP:$BASEPATH/syncposfile/backup_master.status
  48. echo "$(date "+%Y-%m-%d %H:%M:%S") The mymaster.sh, Sync pos file sucess." >> $LOGSPATH/mysql_switch.log
  49. [root@localhost mysql]#

11.3> 回切脚本

  1. [root@localhost mysql]# vim mybackup.sh
  2. #!/bin/sh
  3.  
  4. ##################################################
  5. #File Name  : mybackup.sh
  6. #Description: Empty the slave configuration, retrieve
  7. #             the remote log file and Pos, and open
  8. #             the synchronization
  9. ##################################################
  10.  
  11. BASEPATH=/home/mysql
  12. LOGSPATH=$BASEPATH/logs
  13. source $BASEPATH/.mysqlenv
  14.  
  15. $mysql -e "GRANT ALL PRIVILEGES ON *.* TO 'replication'@'%' IDENTIFIED BY 'replication';flush privileges;"
  16. $mysql -e "set global innodb_support_xa=0;"
  17. $mysql -e "set global sync_binlog=0;"
  18. $mysql -e "set global innodb_flush_log_at_trx_commit=0;"
  19. $mysql -e "flush logs;"
  20. $mysql -e "reset slave all;"
  21.  
  22. if [ -f $BASEPATH/syncposfile/backup_master.status ];then
  23.         New_ReM_File=`cat $BASEPATH/syncposfile/backup_master.status | grep -v File |awk '{print $1}'`
  24.         New_ReM_Position=`cat $BASEPATH/syncposfile/backup_master.status | grep -v File |awk '{print $2}'`
  25.         echo "$(date "+%Y-%m-%d %H:%M:%S") This mybackup.sh, New_ReM_File:$New_ReM_File,New_ReM_Position:$New_ReM_Position" >> $LOGSPATH/mysql_switch.log
  26.         $mysql -e "change master to master_host='$REMOTE_IP',master_port=3306,master_user='replication',master_password='replication',master_log_file='$New_ReM_File',master_log_pos=$New_ReM_Position;"
  27.         $mysql -e "start slave;"
  28.         $mysql -e "show slave status\G;" > $LOGSPATH/slave_status_$(date "+%y%m%d-%H%M").txt
  29.         cat $LOGSPATH/slave_status_$(date "+%y%m%d-%H%M").txt >> $LOGSPATH/mysql_switch.log
  30.         rm -f $BASEPATH/syncposfile/backup_master.status
  31. else
  32.     echo "$(date "+%Y-%m-%d %H:%M:%S") The scripts mybackup.sh running error..." >> $LOGSPATH/mysql_switch.log
  33. fi
  34. [root@localhost mysql]#

11.4> 停止脚本

  1. [root@localhost mysql]# vim mystop.sh
  2. #!/bin/sh
  3.  
  4. ##################################################
  5. #File Name  : mystop.sh
  6. #Description: Set parameters to ensure that the data
  7. #             is not lost, and finally check to see
  8. #             if there are still write operations,
  9. #             the last  minutes to exit
  10.  
  11. ##################################################
  12.  
  13. BASEPATH=/home/mysql
  14. LOGSPATH=$BASEPATH/logs
  15. source $BASEPATH/.mysqlenv
  16.  
  17. $mysql -e "GRANT ALL PRIVILEGES ON *.* TO 'replication'@'%' IDENTIFIED BY 'replication';flush privileges;"
  18. $mysql -e "set global innodb_support_xa=1;"
  19. $mysql -e "set global sync_binlog=1;"
  20. $mysql -e "set global innodb_flush_log_at_trx_commit=1;"
  21. $mysql -e "show master status\G" > $LOGSPATH/mysqlmaster0.states
  22. M_File1=`cat $LOGSPATH/mysqlmaster0.states | awk -F': ' '/File/{print $2}'`
  23. M_Position1=`cat $LOGSPATH/mysqlmaster0.states | awk -F': ' '/Position/{print $2}'`
  24. sleep
  25. $mysql -e "show master status\G" > $LOGSPATH/mysqlmaster1.states
  26. M_File2=`cat $LOGSPATH/mysqlmaster1.states | awk -F': ' '/File/{print $2}'`
  27. M_Position2=`cat $LOGSPATH/mysqlmaster1.states | awk -F': ' '/Position/{print $2}'`
  28.  
  29. i=
  30.  
  31. while true
  32. do
  33.     if [ $M_File1 = $M_File2 ] && [ $M_Position1 -eq $M_Position2 ];then
  34.         echo "$(date "+%Y-%m-%d %H:%M:%S") The mystop.sh, master sync ok.." >> $LOGSPATH/mysql_switch.log
  35.         exit
  36.     else
  37.         sleep
  38.         if [$i -gt  ];then
  39.             break
  40.         fi
  41.         continue
  42.         let i++
  43.     fi
  44. done
  45. echo "$(date "+%Y-%m-%d %H:%M:%S") The mystop.sh, master sync exceed one minutes..." >> $LOGSPATH/mysql_switch.log
  46. [root@localhost mysql]#

二、Keepalived安装与配置

1.两台都安装Keepalived(略)

2.切换原理

Keepalived可实现将虚拟IP地址在实体物理机上来回漂移。Keepalived在转换状态时会依照状态来呼叫配置文件中内置的定义。
当进入Master状态时会呼叫notify_master定义的脚本
当进入Backup状态时会呼叫notify_backup定义的脚本
当keepalived程序终止时呼叫notify_stop定义的脚本
当发现异常情况时进入Fault状态呼叫notify_fault定义的脚本

切换的过程如下：

1.>在Master主机上keepalived运行时执行mycheck.sh脚本不停的检查mysql的运行状态，当发现mysql停止后将keepalived进程杀掉。
2.>此时Slave主机上会接管虚拟IP地址，并调用notify_master定义的脚本
3.>当原Master主机上的mysql和keepalived进程恢复正常后，会调用notify_backup定义的脚本，此时数据库的主端还在Savle主机上。
4.>回切，关闭Slave端的keepavlied进程，会调用notify_stop脚本，同时Master主机上会调用notify_master定义的脚本。此时数据库的主端在Master主机上
5.>启动Slave端的keepavlied进程，会调用notify_backup脚本，此时完成数据同步。

3.Keepalived的配置
在Master端和Savle端均安装好keepalived后，进行配置，修改/etc/keepalived/keepalived.conf文件.
3.1> Master端配置

  1. [root@localhost keepalived]# cat keepalived.conf
  2. global_defs {
  3.    router_id MySQL-HA
  4. } 
  5.  
  6. vrrp_script check_run {
  7. script "/home/mysql/mycheck.sh"
  8. interval
  9. }
  10.  
  11. vrrp_sync_group VG1 {
  12. group {
  13. VI_1
  14. }
  15. }
  16.  
  17. vrrp_instance VI_1 {
  18.     state MASTER
  19.     #state BACKUP
  20.     interface enp0s3
  21.     virtual_router_id
  22.     priority
  23.     advert_int
  24.     #nopreempt
  25.     authentication {
  26.         auth_type PASS
  27.         auth_pass
  28.     }
  29.     track_script {
  30.     check_run
  31.     }
  32.     notify_master /home/mysql/mymaster.sh
  33.     notify_backup /home/mysql/mybackup.sh
  34.     notify_stop /home/mysql/mystop.sh
  35.  
  36.     virtual_ipaddress {
  37.         192.168.158.30/
  38.     }
  39.  
  40.   }

3.2> Slave端配置

  1. [root@localhost keepalived]# cat keepalived.conf
  2. global_defs {
  3.    router_id MySQL-HA
  4. } 
  5.  
  6. vrrp_script check_run {
  7. script "/home/mysql/mycheck.sh"
  8. interval
  9. }
  10.  
  11. vrrp_sync_group VG1 {
  12. group {
  13. VI_1
  14. }
  15. }
  16.  
  17. vrrp_instance VI_1 {
  18.     state MASTER
  19.     #state BACKUP
  20.     interface enp0s3
  21.     virtual_router_id
  22.     priority
  23.     advert_int
  24.     #nopreempt
  25.     authentication {
  26.         auth_type PASS
  27.         auth_pass
  28.     }
  29.     track_script {
  30.     check_run
  31.     }
  32.     notify_master /home/mysql/mymaster.sh
  33.     notify_backup /home/mysql/mybackup.sh
  34.     notify_stop /home/mysql/mystop.sh
  35.  
  36.     virtual_ipaddress {
  37.         192.168.158.30/
  38.     }
  39.   }
  40. [root@localhost keepalived]#

3.3> 重新启动相关服务

  1. # systemctl restart keepalived

三、切换验证

1. 保证两台主机上面keepalived、MySQL服务都是正常启动着的.
2. 停止主端
2.1> 将MySQL进程杀死

  1. [root@localhost ~]# systemctl stop  mysqld

2.2> 检查状态
主端查看脚本切换日志

  1. [root@localhost ~]# tail -100f /home/mysql/logs/mysql_switch.log
  2. ......
  3. -- :: The scripts mycheck.sh is running ...
  4. -- :: The scripts mycheck.sh is running ...
  5. -- :: The scripts mycheck.sh is running ...
  6. -- :: The scripts mycheck.sh is running ...
  7. -- :: The scripts mycheck.sh is running ...
  8. -- :: The mycheck.sh, mysql is down, after switch...

2.3> 主端查看浮动IP地址的切换过程。

  1. #浮动IP地址原先在Master端，如下：
  2. # 切换后，在从Master端验查看，浮动IP已被切走到备机
  3. # 在Slave端查看验证，确认
  4. # 外部ping浮动IP地址效果，有一个丢包

2.4> 主端Keepalived日志/var/log/messages如下：

  1. Aug  :: localhost systemd: Stopping MySQL Server...
  2. Aug  :: localhost systemd: Stopped MySQL Server.
  3. Aug  :: localhost systemd: Stopping SYSV: Start and stop Keepalived...
  4. Aug  :: localhost Keepalived[]: Stopping Keepalived v1.2.13 (/,)
  5. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) sending  priority
  6. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) removing protocol VIPs.
  7. Aug  :: localhost Keepalived_healthcheckers[]: Netlink reflector reports IP 192.168.158.30 removed
  8. Aug  :: localhost keepalived: Stopping keepalived: [  OK  ]
  9. Aug  :: localhost systemd: Stopped SYSV: Start and stop Keepalived.
  10. Aug  :: localhost systemd: Started Session  of user root.
  11. Aug  :: localhost systemd-logind: New session  of user root.
  12. Aug  :: localhost systemd-logind: Removed session .

2.5> 备端查看切换日志/home/mysql/logs/mysql_switch.log

  1. -- :: The scripts mycheck.sh is running ...
  2. -- :: The mymaster.sh, slave sync ok...
  3. -- :: The mymaster.sh, Sync pos file sucess.
  4. -- :: The scripts mycheck.sh is running ...

2.6> 备端查看/var/log/messages.log日志

  1. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) Transition to MASTER STATE
  2. Aug  :: localhost Keepalived_vrrp[]: VRRP_Group(VG1) Syncing instances to MASTER state
  3. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) Entering MASTER STATE
  4. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) setting protocol VIPs.
  5. Aug  :: localhost Keepalived_healthcheckers[]: Netlink reflector reports IP 192.168.158.30 added
  6. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) Sending gratuitous ARPs on enp0s3 for 192.168.158.30
  7. Aug  :: localhost Keepalived_vrrp[]: VRRP_Instance(VI_1) Sending gratuitous ARPs on enp0s3 for 192.168.158.30

# mysql_config_editor set --login-path=local --user=root --port=3306 --password# mysql_config_editor print --all

Keepalived与MySQL互为主从自动切换配置的更多相关文章

  1. 使用keepalived实现mysql主从复制的自动切换

    最近测试了一下mysql+keepalived实现主从自动切换,主从都需要安装keepalived,使用vip漂移实现主从自动切换,这里主要记录的是keepalived的文件配置. 这里mysql搭建 ...

  2. mysql mha 主从自动切换 高可用

    mha(Master High Availability)目前在MySQL多服务器(超过二台),高可用方面是一个相对成熟的解决方案. 一,什么是mha,有什么特性 1. 主服务器的自动监控和故障转移 ...

  3. MySql互为主从配置文件及配置方法

    # Example MySQL config file for medium systems. # # This is for a system with little memory (32M - 6 ...

  4. mysql互为主从(双主)配置

    环境: ubuntu18.04.2 mysql5.7.21 #创建mysql属组 groupadd mysql useradd -g mysql mysql #查看属组 tail /etc/passw ...

  5. mysql互为主从实战设置详解及自动化备份(Centos7.2)

    mysql互为主从实战设置详解(Centos7.2) 第一步:mysql配置  my.cnf配置 服务器1 (10.89.10.90) [mysqld]  server-id=1  log-bin=/ ...

  6. SpringBoot入门教程(三)通过properties实现多个数据库环境自动切换配置

    前面的文章已经介绍了CentOS部署SpringBoot项目从0到1的详细过程,包括Linux安装ftp.Tomcat以及Java jdk的全部过程.这篇文章主要介绍关于springboot如何通过多 ...

  7. java使用Redis7--分布式存储并实现sentinel主从自动切换

    前面实现了分布式存储,也实现了sentinel单点故障时主从自动切换,现在还需要一种机制,实现分布式存储下,单点故障时的主从自动切换. Server配置 # cd /usr/redis/src/tes ...

  8. Dledger的是如何实现主从自动切换的

    前言 hello小伙伴们,今天王子又来继续和大家聊RocketMQ了,之前的文章我们一直说Broker的主从切换是可以基于Dledger实现自动切换的,那么小伙伴们是不是很好奇它究竟是如何实现的呢?今 ...

  9. KeepAlived+MySQL互为主从

    http://blog.csdn.net/socho/article/details/51804720 解决Master单点问题,两台mysql互为主备,双向replication.当一master挂 ...

随机推荐

  1. 微信小程序 - 组件 | 自定义组件 | 组件事件传递页面

    组件 小程序允许我们使用自定义组件的方式来构建页面 类似Vue的小组件 自定义组件 类似于页面,一个自定义组件由 json, wxml, wxss, js 4个文件组成 1.创建 1.创建compon ...

  2. zz目标检测

    deep learning分类 目标检测-HyperNet-论文笔记 06-06 基础DL模型-Deformable Convolutional Networks-论文笔记 06-05 基础DL模型- ...

  3. 洛谷 U87052 一线天

    洛谷 U87052 一线天 题目传送门 题目背景 \(JDFZ\)即将举办第一届"一线天"趣味运动会...... 题目描述 "一线天"运动会在\(JLU\)南岭 ...

  4. 查看tensorflow是否为MKL版本命令

    python -c "import tensorflow; print(tensorflow.pywrap_tensorflow.IsMklEnabled())" source a ...

  5. JS中的箭头函数与this

    转载自:https://juejin.im/post/5aa1eb056fb9a028b77a66fd#heading-1 JavaScript在ES6语法中新增了箭头函数,相较于传统函数,箭头函数不 ...

  6. Kettle Unable to get list of element types for namespace 'pentaho'

    我把公司的kettle5.0升级到7.0之后遇到了这个问题,困扰了很久,百度谷歌都查不到结果,所以只能自己查找原因. 由于已经被搞好了,现在无法截图了,总之就是下面这行报错,遇到这个错误的同学估计也不 ...

  7. flask回顾

    pip install flask from flask import Flask app = Flask(__name__) # 命令行启动,用manager,访问会变的非常慢 pip instal ...

  8. STL——sort函数的实现原理

    实现原理 sort结合了快速排序.堆排序.直接插入排序三种排序方法. 根据不同的数量级别以及不同情况,能自动选用合适的排序方法.当数据量较大时采用快速排序,分段递归.一旦分段后的数据量小于某个阀值,为 ...

  9. [LeetCode] 457. Circular Array Loop 环形数组循环

    You are given a circular array nums of positive and negative integers. If a number k at an index is ...

  10. [LeetCode] 266. Palindrome Permutation 回文全排列

    Given a string, determine if a permutation of the string could form a palindrome. Example 1: Input: ...