? 通常一個網(wǎng)站在初期訪問量都比較小，所以一般的小架構足以支撐。但是，當網(wǎng)站逐漸發(fā)展起來后，隨之而來的是大量的訪問，這時候最先出現(xiàn)的瓶頸就是數(shù)據(jù)庫了。因為數(shù)據(jù)的寫入讀取操作（I/O）是集群中響應速度最慢的，所以在集群建設時就要規(guī)劃好后端存儲架構。

? 后端存儲數(shù)據(jù)庫架構普遍是主從復制，這樣解決了數(shù)據(jù)備份問題。但是，由前端來的讀寫請求都要經(jīng)過主庫，量小沒問題，當量大到超過主庫的性能極限時，主庫分分鐘會宕機。

? 為了避免主庫宕機這種災難性事件的發(fā)生，讀寫分離的設計誕生了！把寫的請求只交給主庫，讀的請求由主庫和從庫一起分攤，這樣就大大減輕了主庫的負擔。

? 大部分公司會由開發(fā)部門在軟件層面實現(xiàn)對數(shù)據(jù)庫的讀寫分離，其次可以選擇讀寫分離的中間件如：TDDL、amoeba、cobar、MySQL-proxy、Atlas、MyCat。

本次測試采用MySQL官方發(fā)布的MySQL-proxy。

官網(wǎng)下載地址（二進制包）：https://downloads.mysql.com/archives/get/file/mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz

測試環(huán)境：

[root@SQL-M ~]# cat /etc/redhat-release?

CentOS release 6.8 (Final)

[root@SQL-M ~]# uname -r

2.6.32-642.el6.x86_64

MySQL-proxy ? IP：192.168.0.86

MySQL-master ?IP：192.168.0.88

MySQL-slave ? IP：192.168.0.90

前提：MySQL主庫與從庫已經(jīng)實現(xiàn)主從復制。

實現(xiàn)主從復制請參考我的前一篇博文：http://yuyicong.blog.51cto.com/11274530/1919158

接下來的操作在proxy服務器上：

[root@SQL-proxy ~]# cd /usr/local/src/

[root@SQL-proxy src]# wget https://downloads.mysql.com/archives/get/file/mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz

[root@SQL-proxy src]# ll -h

total 12M

-rw-r--r-- 1 root root 12M Aug 19 ?2014 mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz

[root@SQL-proxy src]# tar zxf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz -C /usr/local/

[root@SQL-proxy src]# cd ..?

[root@SQL-proxy local]# mv mysql-proxy-0.8.5-linux-el6-x86-64bit/ mysql-proxy-0.8.5

[root@SQL-proxy local]# ll -d?mysql-proxy-0.8.5

drwxr-xr-x ?8 7161 wheel 4096 Aug 19 ?2014 mysql-proxy-0.8.5 ? ?# 看到所屬用戶和組有問題

[root@SQL-proxy local]# chown -R root:root mysql-proxy-0.8.5/ ?# 改為root

[root@SQL-proxy local]# ln -s mysql-proxy-0.8.5/ mysql-proxy ? ?# 必備軟連接

[root@SQL-proxy local]# cd mysql-proxy

[root@SQL-proxy mysql-proxy]# mkdir etc ? ? ? ? ? ? ?# 創(chuàng)建 lua 腳本存放目錄

[root@SQL-proxy mysql-proxy]# mkdir logs ? ? ? ? ? ?# 創(chuàng)建日志目錄

把實現(xiàn)讀寫分離的 lua 腳本復制到 etc 目錄下

[root@SQL-proxy mysql-proxy]# cp share/doc/mysql-proxy/rw-splitting.lua etc/ ??

[root@SQL-proxy mysql-proxy]# cp share/doc/mysql-proxy/admin-sql.lua etc/

創(chuàng)建啟動參數(shù)文件，啟動服務時命令行就不用老長老長的。

[root@SQL-proxy ~]# vim /etc/mysql-proxy.cnf

[mysql-proxy] admin-username=proxy?????#?連接主從mysql共有的用戶 admin-password=123???????#?連接用戶的密碼 proxy-address=192.168.0.86:3306???#?mysql-proxy監(jiān)聽本地工作ip和端口，不加端口默認是4040，為了方便管理這里用3306 proxy-backend-addresses=192.168.0.87:3306????#?指定后端主庫 proxy-read-only-backend-addresses=192.168.0.90:3306??#?指定后端只讀從庫 proxy-lua-script=/usr/local/mysql-proxy/etc/rw-splitting.lua??#?指定實現(xiàn)讀寫分離的lua腳本 admin-lua-script=/usr/local/mysql-proxy/etc/admin-sql.lua?????#?指定管理腳本 pid-file=/var/run/mysql-proxy.pid??? log-file=/usr/local/mysql-proxy/logs/mysql-proxy.log??#?日志位置 log-level=info??#?定義log日志級別，由高到低分別有(error|warning|info|message|debug) daemon=true?????#?以守護進程方式運行 keepalive=true??#?work進程崩潰時，嘗試重啟

啟動服務

[root@SQL-proxy ~]# /usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/etc/mysql-proxy.cnf

2017-04-24 16:40:19: (critical) mysql-proxy-cli.c:326: loading config from '/etc/mysql-proxy.cnf' failed: permissions of /etc/mysql-proxy.cnf aren't secure (0660 or stricter required)

2017-04-24 16:40:19: (message) Initiating shutdown, requested from mysql-proxy-cli.c:328

2017-04-24 16:40:19: (message) shutting down normally, exit code is: 1

！！看到無法啟動，文件權限要改，因為文件里面有賬號密碼。

[root@SQL-proxy ~]# chmod 660 /etc/mysql-proxy.cnf ? ? # 改權限

[root@SQL-proxy ~]# ll /etc/mysql-proxy.cnf?

-rw-rw---- 1 root root 432 Apr 24 16:31 /etc/mysql-proxy.cnf

[root@SQL-proxy ~]# /usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/etc/mysql-proxy.cnf ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?# ?重新啟動

[root@SQL-proxy ~]# netstat -lntup ? # 查看服務

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address ? ? ? ? ? ? ? Foreign Address ? ? ? ? ? ? State ? ? ? PID/Program name ??

tcp ? ? ? ?0 ? ? ?0 192.168.0.86:3306 ? ? ? ? ? 0.0.0.0:* ? ? ? ? ? ? ? ? ? LISTEN ? ? ?3086/mysql-proxy?

老是命令行敲一長串命令肯定不科學了，直接上服務管理腳本。

[root@SQL-proxy?~]#?vim?/etc/init.d/mysql-proxy #!/bin/bash # #?mysql-proxy?This?script?starts?and?stops?the?mysql-proxy?daemon # #?chkconfig:?-?78?30 #?processname:?mysql-proxy #?description:?mysql-proxy?is?a?proxy?daemon?for?mysql#?Source?function?library. .?/etc/rc.d/init.d/functionsprog="/usr/local/mysql-proxy/bin/mysql-proxy"#?Source?networking?configuration. if?[?-f?/etc/sysconfig/network?];?then.?/etc/sysconfig/network fi#?Check?that?networking?is?up. [?${NETWORKING}?=?"no"?]?&&?exit?0DEFAULT_FILE=/etc/mysql-proxy.cnf PROXY_PID=/var/run/mysql-proxy.pidRETVAL=0start()?{echo?-n?$"Starting?MySQL-proxy...??:?"daemon?$prog?--defaults-file=$DEFAULT_FILERETVAL=$?echoif?[?$RETVAL?-eq?0?];?thentouch?/var/lock/subsys/mysql-proxy.lockfi }stop()?{echo?-n?$"Stopping?MySQL-proxy...??:?"killproc?-p?$PROXY_PID?-d?3?$progRETVAL=$?echoif?[?$RETVAL?-eq?0?];?thenrm?-f?/var/lock/subsys/mysql-proxy.lockrm?-f?$PROXY_PIDfi } #?See?how?we?were?called. case?"$1"?instart)start;;stop)stop;;restart)stopstart;;condrestart|try-restart)if?status?-p?$PROXY_PIDFILE?$prog?>&/dev/null;?thenstopstartfi;;status)status?-p?$PROXY_PID?$prog;;*)echo?"Usage:?$0?{start|stop|restart|reload|status|condrestart|try-restart}"RETVAL=1;; esacexit?$RETVAL

[root@SQL-proxy ~]# chmod +x /etc/init.d/mysql-proxy ? # ?給執(zhí)行權限

[root@SQL-proxy ~]# chkconfig mysql-proxy on ? ? ? ? ? # 可以加入開機啟動

測試一下腳本：

[root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?status mysql-proxy?(pid??3086)?is?running... [root@SQL-proxy?~]#? [root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?stop Stopping?MySQL-proxy...??:?????????????????????????????????[??OK??] [root@SQL-proxy?~]#? [root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?status mysql-proxy?is?stopped [root@SQL-proxy?~]#?netstat?-lntup Active?Internet?connections?(only?servers) Proto?Recv-Q?Send-Q?Local?Address???????????????Foreign?Address?????????????State???????PID/Program?name??? tcp????????0??????0?0.0.0.0:22??????????????????0.0.0.0:*???????????????????LISTEN??????1079/sshd??????????? tcp????????0??????0?:::22???????????????????????:::*????????????????????????LISTEN??????1079/sshd??????????? [root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?start Starting?MySQL-proxy...??:?????????????????????????????????[??OK??] [root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?restart Stopping?MySQL-proxy...??:?????????????????????????????????[??OK??] Starting?MySQL-proxy...??:?????????????????????????????????[??OK??] [root@SQL-proxy?~]#? [root@SQL-proxy?~]#?netstat?-lntup??????????????? Active?Internet?connections?(only?servers) Proto?Recv-Q?Send-Q?Local?Address???????????????Foreign?Address?????????????State???????PID/Program?name??? tcp????????0??????0?192.168.0.86:3306???????????0.0.0.0:*???????????????????LISTEN??????3143/mysql-proxy

?

以上MySQL-proxy服務器搭建完成，但是用于連接后端數(shù)據(jù)庫的用戶：proxy還需要在數(shù)據(jù)庫端創(chuàng)建

數(shù)據(jù)庫Master端：創(chuàng)建proxy用戶，給增刪改查權限

[root@SQL-M?~]#?mysql?-uroot?-p Enter?password:? Welcome?to?the?MySQL?monitor.??Commands?end?with?;?or?\g. Your?MySQL?connection?id?is?3 Server?version:?5.5.55-log?MySQL?Community?Server?(GPL)Copyright?(c)?2000,?2017,?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.Master>? Master>?grant?insert,delete,update,select?on?*.*?to?proxy@'192.168.0.86'?identified?by?'123'; Query?OK,?0?rows?affected?(0.00?sec)Master>?select?user,host?from?mysql.user;???????????????????????????????????????+-------+--------------+ |?user??|?host?????????| +-------+--------------+ |?root??|?127.0.0.1????| |?rep???|?192.168.0.%??| |?proxy?|?192.168.0.86?| |?root??|?localhost????| +-------+--------------+ 4?rows?in?set?(0.00?sec)Master>?show?grants?for?proxy@'192.168.0.86'; +------------------------------------------------------------------------------------------------------------------------------------------+ |?Grants?for?proxy@192.168.0.86????????????????????????????????????????????????????????????????????????????????????????????????????????????| +------------------------------------------------------------------------------------------------------------------------------------------+ |?GRANT?SELECT,?INSERT,?UPDATE,?DELETE?ON?*.*?TO?'proxy'@'192.168.0.86'?IDENTIFIED?BY?PASSWORD?'*23AE809DDACAF96AF0FD78ED04B6A265E05AA257'?| +------------------------------------------------------------------------------------------------------------------------------------------+ 1?row?in?set?(0.00?sec)

Slave端：此時已經(jīng)與主庫一致?lián)碛辛藀roxy用戶，但是從庫只能讀（select），所以要對proxy回收權限。

Slave>?show?grants?for?proxy@'192.168.0.86'; +------------------------------------------------------------------------------------------------------------------------------------------+ |?Grants?for?proxy@192.168.0.86????????????????????????????????????????????????????????????????????????????????????????????????????????????| +------------------------------------------------------------------------------------------------------------------------------------------+ |?GRANT?SELECT,?INSERT,?UPDATE,?DELETE?ON?*.*?TO?'proxy'@'192.168.0.86'?IDENTIFIED?BY?PASSWORD?'*23AE809DDACAF96AF0FD78ED04B6A265E05AA257'?| +------------------------------------------------------------------------------------------------------------------------------------------+ 1?row?in?set?(0.00?sec)Slave>?revoke?insert,update,delete?on?*.*?from?proxy@'192.168.0.86';?#?只留查詢權限 Query?OK,?0?rows?affected?(0.00?sec)Slave>?show?grants?for?proxy@'192.168.0.86';???????????????????????? +------------------------------------------------------------------------------------------------------------------+ |?Grants?for?proxy@192.168.0.86????????????????????????????????????????????????????????????????????????????????????| +------------------------------------------------------------------------------------------------------------------+ |?GRANT?SELECT?ON?*.*?TO?'proxy'@'192.168.0.86'?IDENTIFIED?BY?PASSWORD?'*23AE809DDACAF96AF0FD78ED04B6A265E05AA257'?| +------------------------------------------------------------------------------------------------------------------+ 1?row?in?set?(0.00?sec)

測試讀寫分離

為了方便測試，修改 rw-splitting.lua 腳本里觸發(fā)讀寫分離參數(shù)

[root@SQL-proxy?~]#?vim?/usr/local/mysql-proxy/etc/rw-splitting.lua? --?connection?pool if?not?proxy.global.config.rwsplit?thenproxy.global.config.rwsplit?=?{min_idle_connections?=?1,??#?默認超過4個連接數(shù)時，才開始讀寫分離，改為1max_idle_connections?=?8,??#?默認最大連接數(shù)8，不動它is_debug?=?false} end[root@SQL-proxy?~]#?/etc/init.d/mysql-proxy?restart???????#?重啟一下 Stopping?MySQL-proxy...??:?????????????????????????????????[??OK??] Starting?MySQL-proxy...??:?????????????????????????????????[??OK??]

數(shù)據(jù)庫Master端

Master>?create?database?proxy;?????????#?建個庫 Query?OK,?1?row?affected?(0.00?sec)Master>?create?table?master(id?int(2),name?char(10));??#?停掉從庫?IO線程后再建個表 Query?OK,?0?rows?affected?(0.18?sec)Master>?desc?master; +-------+----------+------+-----+---------+-------+ |?Field?|?Type?????|?Null?|?Key?|?Default?|?Extra?| +-------+----------+------+-----+---------+-------+ |?id????|?int(2)???|?YES??|?????|?NULL????|???????| |?name??|?char(10)?|?YES??|?????|?NULL????|???????| +-------+----------+------+-----+---------+-------+ 2?rows?in?set?(0.00?sec)

Slave端

Slave>?show?databases; +--------------------+ |?Database???????????| +--------------------+ |?information_schema?| |?mysql??????????????| |?performance_schema?| |?proxy??????????????|?????#?新建的庫已經(jīng)有了 |?school?????????????| |?test???????????????| +--------------------+ 6?rows?in?set?(0.00?sec)Slave>?stop?slave?io_thread;??????#?停掉?IO?線程 Query?OK,?0?rows?affected?(0.00?sec)Slave>?show?slave?status\G?? ***************************?1.?row?***************************Slave_IO_State:?Master_Host:?192.168.0.88Master_User:?repMaster_Port:?3306Connect_Retry:?60Master_Log_File:?mysql-bin.000019Read_Master_Log_Pos:?351Relay_Log_File:?relay-bin.000011Relay_Log_Pos:?497Relay_Master_Log_File:?mysql-bin.000019Slave_IO_Running:?NoSlave_SQL_Running:?YesSlave>?use?proxy; Database?changedSlave>?create?table?slave(id?int(2),name?char(10));??#?建個表 Query?OK,?0?rows?affected?(0.00?sec)Slave>?desc?slave; +-------+----------+------+-----+---------+-------+ |?Field?|?Type?????|?Null?|?Key?|?Default?|?Extra?| +-------+----------+------+-----+---------+-------+ |?id????|?int(2)???|?YES??|?????|?NULL????|???????| |?name??|?char(10)?|?YES??|?????|?NULL????|???????| +-------+----------+------+-----+---------+-------+ 2?rows?in?set?(0.00?sec)Slave>?insert?into?slave?values(90,'slave');????#?插入一條數(shù)據(jù) Query?OK,?1?row?affected?(0.00?sec)Slave>?select?*?from?slave; +------+-------+ |?id???|?name??| +------+-------+ |???90?|?slave?| +------+-------+ 1?row?in?set?(0.00?sec)

模擬遠程連接MySQL-proxy服務器進行讀寫操作

[root@SQL-proxy?~]#?mysql?-h192.168.0.86?-uproxy?-P3306?-p Enter?password:? Welcome?to?the?MySQL?monitor.??Commands?end?with?;?or?\g. Your?MySQL?connection?id?is?12 Server?version:?5.5.55-log?MySQL?Community?Server?(GPL)Copyright?(c)?2000,?2017,?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>? mysql>?use?proxy; Database?changed mysql>? mysql>?show?tables;???#?show?出來的只有master這個表 +-----------------+ |?Tables_in_proxy?| +-----------------+ |?master??????????| +-----------------+ 1?row?in?set?(0.01?sec)mysql>?desc?master; +-------+----------+------+-----+---------+-------+ |?Field?|?Type?????|?Null?|?Key?|?Default?|?Extra?| +-------+----------+------+-----+---------+-------+ |?id????|?int(2)???|?YES??|?????|?NULL????|???????| |?name??|?char(10)?|?YES??|?????|?NULL????|???????| +-------+----------+------+-----+---------+-------+ 2?rows?in?set?(0.00?sec)mysql>?insert?into?master?values(88,'master');??#?往master表里插入數(shù)據(jù) Query?OK,?1?row?affected?(0.00?sec)????????<<---?寫入是?OK?的mysql>?select?*?from?master; ERROR?1146?(42S02):?Table?'proxy.master'?doesn't?exist??#?明顯查不到的，因為去找從庫了，從庫上沒有這表。mysql>?show?tables;???#?我們show時只能看到?master?表，好像show只能找主庫。 +-----------------+ |?Tables_in_proxy?| +-----------------+ |?master??????????| +-----------------+ 1?row?in?set?(0.00?sec)mysql>?select?*?from?slave;??#?我們直接查?slave?表 +------+-------+ |?id???|?name??| +------+-------+ |???90?|?slave?|?????????<<---?查到了，讀操作成功 +------+-------+ 1?row?in?set?(0.00?sec)mysql>

恢復 slave IO 線程

Slave>?start?slave?io_thread; Query?OK,?0?rows?affected?(0.00?sec)Slave>?show?slave?status\G??? ***************************?1.?row?***************************Slave_IO_State:?Waiting?for?master?to?send?eventMaster_Host:?192.168.0.88Master_User:?repMaster_Port:?3306Connect_Retry:?60Master_Log_File:?mysql-bin.000019Read_Master_Log_Pos:?1566Relay_Log_File:?relay-bin.000012Relay_Log_Pos:?1468Relay_Master_Log_File:?mysql-bin.000019Slave_IO_Running:?YesSlave_SQL_Running:?Yes

再次模擬遠程連接MySQL-proxy服務器查?master 表

[root@SQL-proxy?~]#?mysql?-h192.168.0.86?-uproxy?-P3306?-p Enter?password:? Welcome?to?the?MySQL?monitor.??Commands?end?with?;?or?\g. Your?MySQL?connection?id?is?12 Server?version:?5.5.55-log?MySQL?Community?Server?(GPL)Copyright?(c)?2000,?2017,?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>? mysql>?use?proxy; Database?changed mysql>? mysql>?select?*?from?master; +------+--------+ |?id???|?name???| +------+--------+ |???88?|?master?|????????<<----由于從庫恢復后開始復制主庫數(shù)據(jù)，所以可以查到了。 +------+--------+ 1?row?in?set?(0.00?sec)

以上MySQL-proxy讀寫分離完成。

存在的問題：

? ? 當模擬前端連接MySQL-proxy服務器并進行數(shù)據(jù)庫操作時，MySQL-proxy服務器端屏幕有信息輸出，不知道為什么？

信息如下：

[root@SQL-proxy ~]# ? ? server default db: proxy

? ? client default db: school

? ? syncronizing

? ? server default db: proxy

? ? client default db: school

? ? syncronizing

? ? server default db: school

? ? client default db: proxy

? ? syncronizing

轉載于:https://blog.51cto.com/yuyicong/1919799

總結

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