MySQL读写分离服务配置

使用mycat实现

（都在代理服务器上执行）
安装jdk1.8（代理服务器上执行）

1. 解压缩包：

tar -xzvf jdk-8u161-linux-x64.tar.gz -C /usr/local/java

3. 环境变量文件/etc/profile配置

export JAVA_HOME=/usr/local/java/jdk1.8.0_161
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib:$CLASSPATH
export JAVA_PATH=${JAVA_HOME}/bin:${JRE_HOME}/bin
export PATH=$PATH:${JAVA_PATH}

注意：配置环境变量时，中间不能有空格
3. 使用source命令使修改即时生效，无需重启服务器

source /etc/profile

4. 解压缩包：

tar -zxvf Mycat-server-1.6.7.1-release-20190627191042-linux.tar.gz 

（任意目录都可以）

原

把下面 user name ="usr"等删掉

schema.xml是最主要的配置项，首先看我的配置文件database=“mytest” 必须是主从库都存在的数据库。
vim schema.xml （全部删完）
重新加进去

    
    
    
         select user() 
        
            
        
    

1. 查询用户密码命令：select host,user,authentication_string from mysql.user

问题一： 增加远程访问

use mysql;
update user set host='%' where user='root';
flush privileges;
select host,user from user ;

问题二：密码编码方式不同，改

ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY 

对比

需进入bin目录下
启动：./mycat start(后台启动) ./mycat console(前台启动)
停止：./mycat stop
重启：./mycat restart
如果在启动时发现异常，在logs目录中查看日志。
wrapper.log 为程序启动的日志，启动时的问题看这个
mycat.log 为脚本执行时的日志，SQL脚本执行报错后的具体错误内容，查看这个文件。
mycat.log是最新的错误日志，历史日志会根据时间生成目录保存。

成功的mycat.log

2021-11-26 23:24:44.684  INFO [$_NIOREACTOR-0-RW] (io.mycat.backend.datasource.PhysicalDatasource$1$1.connectionAcquired(PhysicalDatasource.java:514)) - connection id is 14
2021-11-26 23:24:44.685  INFO [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.handler.NewConnectionRespHandler.connectionAcquired(NewConnectionRespHandler.java:44)) - connectionAcquired MySQLConnection [id=14, lastTime=1637940284685, user=root, schema=test, old shema=test, borrowed=true, fromSlaveDB=true, threadId=18, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=192.168.202.151, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
2021-11-26 23:24:44.685  INFO [$_NIOREACTOR-0-RW] (io.mycat.backend.datasource.PhysicalDatasource$1$1.connectionAcquired(PhysicalDatasource.java:514)) - connection id is 15
2021-11-26 23:24:44.685  INFO [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.handler.NewConnectionRespHandler.connectionAcquired(NewConnectionRespHandler.java:44)) - connectionAcquired MySQLConnection [id=15, lastTime=1637940284685, user=root, schema=test, old shema=test, borrowed=true, fromSlaveDB=true, threadId=19, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=192.168.202.151, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
2021-11-26 23:29:44.676  INFO [Timer0] (io.mycat.backend.datasource.PhysicalDatasource.createByIdleLitte(PhysicalDatasource.java:397)) - create connections ,because idle connection not enough ,cur is 5, minCon is 10 for hostS1
2021-11-26 23:29:44.685  INFO [$_NIOREACTOR-0-RW] (io.mycat.backend.datasource.PhysicalDatasource$1$1.connectionAcquired(PhysicalDatasource.java:514)) - connection id is 16

成功的wrapper.log
vim wrapper.log

 STATUS | wrapper  | 2021/11/26 23:19:39 | TERM trapped.  Shutting down.
STATUS | wrapper  | 2021/11/26 23:19:40 | <-- Wrapper Stopped
STATUS | wrapper  | 2021/11/26 23:19:41 | --> Wrapper Started as Daemon
STATUS | wrapper  | 2021/11/26 23:19:41 | Launching a JVM...
INFO   | jvm 1    | 2021/11/26 23:19:41 | Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=64M; support was removed in 8.0
INFO   | jvm 1    | 2021/11/26 23:19:43 | Wrapper (Version 3.2.3) http://wrapper.tanukisoftware.org
INFO   | jvm 1    | 2021/11/26 23:19:43 |   Copyright 1999-2006 Tanuki Software, Inc.  All Rights Reserved.
INFO   | jvm 1    | 2021/11/26 23:19:43 |
INFO   | jvm 1    | 2021/11/26 23:19:44 | MyCAT Server startup successfully. see logs in logs/mycat.log

查看端口：netstat -anultp
8066业务端口 9066管理端口

show @@help;  #查看帮助

show @@heartbeat；#查看心跳RS_CODE 1 表示正常
show @@datasource; #查看读写配置情况W 写 R 读

8066端口  在此进行业务操作
端口都在代理机上

1.堆内存jvm不够
JVM exited while loading the application.
启动mycat后异常次 JVM exited while loading the application. 原因：初始化堆指定过小

INFO   | jvm 1    | 2018/10/12 17:12:25 | # There is insufficient memory for the Java Runtime Environment to continue.
INFO   | jvm 1    | 2018/10/12 17:12:25 | # Native memory allocation (mmap) failed to map 715849728 bytes for committing reserved memory.
INFO   | jvm 1    | 2018/10/12 17:12:25 | # An error report file with more information is saved as:
INFO   | jvm 1    | 2018/10/12 17:12:25 | # /usr/local/software/mycat/hs_err_pid8956.log
ERROR  | wrapper  | 2018/10/12 17:12:26 | JVM exited while loading the application.
STATUS | wrapper  | 2018/10/12 17:12:31 | Launching a JVM...
INFO   | jvm 2    | 2018/10/12 17:12:32 | Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=64M; support was removed in 8.0
INFO   | jvm 2    | 2018/10/12 17:12:32 | Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000715550000, 715849728, 0) failed; error='Cannot allocate memory' (errno=12)

修改mycat/conf/wrapper.conf   
第40行 wrapper.java.initmemory=30  将3改为30
./mycat start    再次启动
./mycat status  查看状态

问题我自己虚拟机本来就是30，并且加##默认
去除井号改30为40 成功
2.自己配置的问题
例如：没有添加好数据库test等。